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Effect of training on parathyroid hormone and bone turnover marker profile in relation to vitamin D supplementation in footballers

The aim of the study was to assess the impact of vitamin D supplementation and regular physical activity on 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH) and bone turnover marker concentration in footballer.





Latest research in football - week 52 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Does maturity estimation, 2D:4D and training load measures explain physical fitness changes of youth football players?

Reference: BMC Pediatr. 2022 Dec 20;22(1):726. doi: 10.1186/s12887-022-03801-5.

Authors: Rui Miguel Silva, Filipe Manuel Clemente, Francisco González-Fernández, Hadi Nobari, Hamed Haghighi, José Ma Cancela Carral

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Summary: The purpose of the present study was two-fold: (1) To analyse physical fitness changes of youth football players after a full-season; and (2) to examine whether physical fitness changes are explainable by estimated maturity status, 2digit:4digit ratio (2D:4D) from each hand and training load (TL) measures. Twenty-seven youth elite Under-15 football players were daily monitored for training load measures during 38 weeks. At the beginning and at the end of the season, all players were assessed for physical fitness. Also, the maturity status estimation and the length of the second and fourth digits of both hands were collected at the beginning of the season. Significant differences were found for all physical fitness measures after the season. The second and fourth digits of left and right hands had negative moderate correlations with change of direction (COD) changes (r=-.39 to - 0.45 | p = .05 to 0.02). Also, the maturity offset measure had negative moderate correlations with COD changes (r=-.40 | p = .04). From the reported significant correlations, the maturity offset, Left 4D, Right 2D and Right 4D significantly predicted the Mod.505 COD test changes (β = 0.41, p = .04; β = -0.41, p = .04; β = -0.45, p = .02; and β = -0.44, p = .03, respectively). The maturity offset and the 2D:4D measures have the potential to predict COD performance changes over-time in youth football players. Given the lack of associations between the maturity estimation, 2D:4D and training load measures, with the overall physical fitness measures, coaches should rely only at COD changes.



#2 Study on Nutritional Knowledge, Attitude and Behavior of Chinese School Football Players

Reference: Children (Basel). 2022 Dec 6;9(12):1910. doi: 10.3390/children9121910.

Authors: Yao Chen, Yingshuang Sun, Zhiyun Liu, Donglin Hu

Summary: This study aims to validate previous structural models of factors influencing dietary behavior changes and construct the knowledge, attitude, and behavioral models of youth school football players. 279 school football players aged 12-17 years in Grades 7-12 in Hunan Province, China, completed a questionnaire to collect data on sports nutrition knowledge, attitudes, and behavior. A structural equation model (SEM) was built based on the knowledge-attitude-behavior (KAB) model and the theory of planned behavior (TPB) model to introduce nutritional knowledge directly or by altering attitudes into the dietary behavior path of players. Four factors affecting dietary behaviors were involved in the hypothetical structure, which consists of the following hypotheses: (1) nutrition knowledge affects the attitude towards sports nutrition (H1); (2) nutrition knowledge affects dietary behaviors (H2); (3) nutrition knowledge affects subjective norms (H3); (4) nutrition knowledge affects perceived behavioral control (H4); (5) subjective norms affect dietary behaviors (H5); and 6) perceived behavioral control affects dietary behaviors (H6). Confirmatory factor analysis (CFA) revealed that the reliability, convergent validity, and discriminant validity of the built SEM conformed to the measured relationships in each dimension. In the final structural model, it was found that nutrition knowledge had a direct impact on the attitudes of players and affected their dietary behaviors in a direct manner or through their subjective norms and perceived behavioral control. The results are in agreement with the TPB-based KAB chain and support the KAB theory for youth school football players in Hunan Province, China.



#3 Examining the Effects of Mirror Therapy on Psychological Readiness and Perception of Pain in ACL-Injured Female Football Players

Reference: J Funct Morphol Kinesiol. 2022 Dec 14;7(4):113. doi: 10.3390/jfmk7040113.

Authors: Tiziana D'Isanto, Francesca D'Elia, Giovanni Esposito, Gaetano Altavilla, Gaetano Raiola

Summary: Virtual reality-guided imagery (VRGI) and mirror therapy (MT) have been used in isolation to treat patients suffering from different injuries. However, no attempts have been made to understand the effects of combined VRGI and MT added to conventional physical therapy, and no information exists regarding perceptual responses to these rehabilitation strategies in female football players. Thus, this study aimed to examine the effect of MT added to conventional rehabilitation on psychological readiness and perception of pain in ACL-injured female football players. Thirty ACL-injured female football players competing in the 2nd and 3rd Italian tier who underwent an ACL rehabilitation program from the same clinic participated in this study. Players were randomly distributed in an MT group (n = 15) and a CON group (n = 15). All participants reported their perception of pain on a VAS before and after the interventions and their psychological readiness to return to sport after ACL injury and reconstruction surgery on the ACL-RSI scale after the intervention. An independent-sample t-test was performed to assess between-group differences in post-intervention ACL-RSI, and a further independent-sample t-test to assume non-significant differences between VAS values before the intervention. A two-way repeated-measures analysis of variance was used to test the null hypothesis of no different change in VAS over time between groups. After the intervention, the MT group perceived largely greater psychological readiness (p < 0.01). MT and CON groups experienced a large reduction in VAS after the intervention (p < 0.001). However, a small time × group interaction was observed (p = 0.023). MT reported a greater perception of the psychological readiness of the soccer players and a lower perception of pain than those who performed conventional therapy.



#4 On-field rehabilitation in football: Current knowledge, applications and future directions

Reference: Front Sports Act Living. 2022 Dec 5;4:970152. doi: 10.3389/fspor.2022.970152. eCollection 2022.

Authors: Mark Armitage, Stuart A McErlain-Naylor, Gavin Devereux, Marco Beato, Matthew Buckthorpe

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#5 Alcohol related harms and elite men's football

Reference: BMJ. 2022 Dec 21;379:o2906. doi: 10.1136/bmj.o2906.

Author: Robin Ireland

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#6 Alcohol related disorders among elite male football players in Sweden: nationwide cohort study

Reference: BMJ. 2022 Dec 21;379:e074093. doi: 10.1136/bmj-2022-074093.

Authors: Peter Ueda, Björn Pasternak, Henrik Svanström, Carl-Emil Lim, Martin Neovius, Magnus Forssblad, Jonas F Ludvigsson, Manzur Kader

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Summary: The aim was to assess whether male elite football players are at increased risk of alcohol related disorders compared with men from the general population, and whether such an increased risk would vary on the basis of calendar year of the first playing season in the top tier of competition, age, career length, and goal scoring abilities. 6007 male football players who had played in the Swedish top division, Allsvenskan, from 1924 to 2019 and 56 168 men from the general population matched to players based on age and region of residence participated in this study. Primary outcome was alcohol related disorders (diagnoses recorded in death certificates, during hospital admissions and outpatient visits, or use of prescription drugs for alcohol addiction); secondary outcome was disorders related to misuse of other drugs. During follow-up up to 31 December 2020, 257 (4.3%) football players and 3528 (6.3%) men from the general population received diagnoses of alcohol related disorders. In analyses accounting for age, region of residence, and calendar time, risk of alcohol related disorders was lower among football players than among men from the general population (hazard ratio 0.71, 95% confidence interval 0.62 to 0.81). A reduced risk of alcohol related disorders was observed for football players who played their first season in the top tier in the early 1960s and later, while no significant difference versus men from the general population was seen in the risk for football players from earlier eras. The hazard ratio was lowest at around age 35 years, and then increased with age; at around age 75 years, football players had a higher risk of alcohol related disorders than men from the general population. No significant association was seen between goal scoring, number of games, and seasons played in the top tier and the risk of alcohol related disorders. Risk of disorders related to other drug misuse was significantly lower among football players than the general population (hazard ratio 0.22, 95% confidence interval 0.15 to 0.34). In this nationwide cohort study, male football players who had played in the Swedish top tier of competition had a significantly lower risk of alcohol related disorders than men from the general population.



#7 Research on women's football: a scoping review

Reference: Sci Med Footb. 2022 Dec 1;6(5):549-558. doi: 10.1080/24733938.2020.1868560. Epub 2021 Jan 8.

Authors: Katrine Okholm Kryger, Albert Wang, Ritan Mehta, Franco M Impellizzeri, Andrew Massey, Alan McCall

Summary: This study aims to scope available peer-reviewed literature published in a FIFA language to understand the current quantity of research on women's football. Five databases were searched on the 15/12/2019. Studies were included when containing original research published in a peer-reviewed journal around female competitive football of any level, any age and on any subject. Author, journal, title and abstract of all included studies were scoped. Population assessed number of participants, level of play, age level of football and publication theme(s) were extracted. A total of 1,634 articles were scoped. The oldest publication dated back to 1939, whilst a total of 202 studies were gathered from 2019. The publication theme most frequently researched was sports medicine (N = 521) followed by strength and conditioning (N = 331) and sociology (N = 299). The majority of studies has focussed on elite (N = 442), senior (N = 977) players. A continuous growth in research attention has been seen. However, the numbers are not comparable to current research output levels in men's football. This study represents an essential first step in a larger 'research agenda-setting' project to determine research priorities for women's football during the next 10 years.



#8 The menstrual cycle and football: The experiences of African women football players

Reference: Sci Med Footb. 2022 Dec 1;6(5):626-632. doi: 10.1080/24733938.2021.2005252.

Authors: Nonhlanhla S Mkumbuzi, Senanile B Dlamini, Fidelis Chibhabha, Fredrick M Govere, Lucinda Manda-Taylor

Summary: The menstrual cycle is a normal biological process in women and girls. However, it is often the reason why they tend to be excluded from football medicine research. Consequently, our understanding of the menstrual cycle and football performance is still limited, especially in African women football players. The study aimed to explore African women football players' current and historical menstrual cycle status, menstrual symptoms, lived experiences, and perceptions of the menstrual cycle. Women football players at the COSAFA Women's Championship 2020 completed demographic questionnaires and the Moos Menstrual Distress Questionnaire. The main findings were that 90% of the players did not use contraceptives, . Most of the players had access to their preferred choice of sanitary product; however, 36% used alternatives such as old rags during their periods, . The most commonly reported symptoms during menses were abdominal cramps (53%), headache (41%), mood swings (41%) and irritability (47%). Further, players reported irritability (48%), mood swings (52%), and breast tenderness (48%) in the week before their period. The low use of contraceptives is likely due to community level socio-cultural factors. While the use of old rags as impromptu sanitary products is likely because they cannot always afford their preferred choice. Menstrual symptoms can affect training and competition; therefore, team support personnel should be aware of the menstrual cycle's implications for African women football players and their effect on athletic performance and well-being. Additionally, team support personnel ought to be mindful of African women football players' socio-economic and religio-cultural contexts and their interaction with biological processes such as the menstrual cycle and contraceptive use.



#9 Nitric oxide therapy is beneficial to rehabilitation in professional soccer players: clinical and experimental studies

Reference: Med Gas Res. 2023 Jul-Sep;13(3):128-132. doi: 10.4103/2045-9912.344983.

Authors: Victoria A Zaborova, Alexandra V Butenko, Anatoly B Shekhter, Alexey L Fayzullin, Alexander V Pekshev, Natalia B Serejnikova, Ol'ga V Chigirintseva, Kira Yu Kryuchkova, Konstantin G Gurevich

Summary: Nitric oxide can activate neutrophils and macrophages, facilitate the synthesis of collagen, which allows significantly accelerating the regeneration of traumatized tissues. We studied the effects of nitric oxide-containing gas flow generated by plasma-chemical device "Plason" in a rat model of full-thickness wounds. Histological and morphometric analyses revealed that Plason treated wounds expressed significantly fewer signs of inflammation and contained a more mature granulation tissue on day 4 after the operation. Considering the results of the experimental study, we applied the Plason device in sports medicine for the treatment of lower limb bruises of 34 professional soccer players. Athletes were asked to assess the intensity of pain with the Visual Analogue Scale. Girths of their lower limbs were measured over the course of rehabilitation. Nitric oxide therapy of full-thickness wounds inhibited inflammation and accelerated the regeneration of skin and muscle tissues. Compared with the control, we observed a significant reduction in pain syndrome on days 2-7 after injuries, edema, and hematoma, and shortened treatment duration. This pilot study indicates that the use of nitric oxide is a promising treatment method for sports injuries.



#10 Did the quarantine period of covid-19 interfere with the physical demands of central referees and assistants in professional soccer in a high level competition in Brazil?

Reference: Sci Sports. 2022 May;37(3):184-190. doi: 10.1016/j.scispo.2021.04.007. Epub 2021 Sep 28.

Authors: A A B Preissler, P Schons, L F M Kruel

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Summary: This study compares the performance demanded from central referees and soccer assistants during professional games before and after the quarantine of COVID-19 during the same competition. Ten central referees and 19 assistants were monitored. Using a watch with Global Positioning System technology and a heart rate monitor, data were obtained of the distance they moved and information on their heart rate. A game before the quarantine period was compared to a game played 128 days after the quarantine period. These participants represented all the referees who played at least one game in the pre- and post-quarantine period of the same high-level competition in Brazil. The results indicated that the total distance, average, and maximum heart rate did not present significant differences between the pre-and post-quarantine time of the central and assistant referees, except for the distance covered by the assistant referees in the second half, which was significantly greater in the post-quarantine period (Δ% = 6.27; P = 0.034). In conclusion, the central referees and assistants' performance was not affected after the 128-day quarantine period compared to the traditional transition period between the 37-day seasons.



#11 Sport specialization in Swedish football players: Investigating a model of antecedents and outcomes

Reference: Eur J Sport Sci. 2022 Dec 28;1-9. doi: 10.1080/17461391.2022.2153084. Online ahead of print.

Authors: Tor Söderström, Alex C Garn

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Summary: Drawing on data from the present and former football players (N = 1026) selected to a national football talent programme at the age of 15, this study explores a model of sport specialisation. We examined three specific aspects of sport specialisation including early football specialisation, participation in youth elite football training environments (i.e. academies) and enrolment in upper secondary football specialisation schools. Antecedents of these sport specialisation factors included gender (i.e. sociocultural), grit (i.e. personality) and perceptions of family finances (i.e. social). Outcomes focused on adult football participation at the age of 21 including elite skill acquisition (i.e. playing elite football) and personal development (i.e. participation in non-elite football). Findings revealed that females were less likely to gain access to elite football training or school specialisation environments. There was also a positive association between grit and participation in elite training environments. In terms of outcomes, players, who got trained in elite training environments during adolescence, were twice as likely to play elite football at the age of 21, while those who attended football specialisation schools were more likely to participate in non-elite football at the age of 21. Early specialisation was not associated with either adult participation outcome. This is one of the few studies to date addressing diverse antecedents and outcomes of sport specialisation factors. Understanding how sport specialisation practices relate to future skill acquisition and personal development can provide guidance for maximising the benefits of youth sport programming.



#12 The perception of injury risk and prevention among football players: A systematic review

Reference: Front Sports Act Living. 2022 Dec 7;4:1018752. doi: 10.3389/fspor.2022.1018752. eCollection 2022.

Authors: Beatriz Cardoso-Marinho, Ana Barbosa, Caroline Bolling, José Pedro Marques, Pedro Figueiredo, João Brito

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Summary: Football is associated with a certain risk of injury, leading to short- and long-term health consequences. However, the perception of football players about injury risk and prevention strategies is poorly documented. The present article reviewed the literature about perceptions, beliefs, attitudes and knowledge toward injury risk and prevention strategies in football players. An electronic search was performed in PubMed, Scopus, Web of Science, and APA PsychINFO until July 2022. Studies were eligible if they included the perceptions, beliefs, attitudes, and knowledge about injury risk and prevention in football players from any competitive level. The risk of bias was assessed in included studies using the Joanna Briggs Institute critical appraisal checklist. A total of 14 studies were included. Most football players agreed that their risk of injury is high and prevention strategies are important, however they do not intend to use some of these strategies. The most frequent perceived injury risk factors were low muscle strength, lack of physical fitness, fatigue, excessive training and type and condition of surfaces. The most frequent perceived injury prevention factors were warm-up, workload monitoring and strength and conditioning training. It is essential to acknowledge perceived injury risk factors, as well as a better understanding of how coaching and medical departments' perceptions match with players' perceptions, and a modification in the perceptions of the several stakeholders at different levels of action.



#13 Changes in Performance on Common Return-to-Sport Tests During a Collegiate Women's Soccer Season: Implications for Baseline Testing

Reference: Sports Health. 2022 Dec 27;19417381221146556. doi: 10.1177/19417381221146556.

Authors: Melissa M Montgomery, Steven Carranza

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Summary: Baseline testing of objective lower limb function may help clinicians make more informed return-to-sport (RTS) decisions in the event of an anterior cruciate ligament (ACL) injury. However, as these tests are based on physical performance, it is possible that they improve during the season as athletes get stronger and fitter. Hence, it may be difficult to ascertain the patient's preinjury status and have an accurate reference for comparison when determining readiness for RTS. The purpose of this study was to examine changes in common ACL RTS tests during a college soccer season to determine the most appropriate time to perform baseline testing. We hypothesized that the hop test performance will improve across the season. A total of 31 women's soccer players from 1 NCAA Division I university agreed to participate this study. Participants performed 4 single-leg hop tests and the 505-agility test to measure cutting speed on 3 occasions: preseason (PRE), midseason (MID), and end-of-season (END). Performance on each test was compared across days to determine whether performance increased during the season. As a secondary analysis, limb symmetry index (LSI) was also compared across the season. A total of 23 participants (age, 19.7 ± 1.3 years; height, 1.69 ± 0.07 m; weight 60.9 ± 7.2 kg) completed all 3 testing sessions during the season. Performance during PRE was better than MID and END for all hop tests (all P < 0.01). LSI did not change during the season (P value range, 0.18-0.79). Performance on the hop tests was best during preseason and declined thereafter, which may be reflective of cumulative fatigue. Baseline testing of RTS tests performed during preseason may provide an accurate representation of an athlete's best abilities over the course of a collegiate soccer season. Preseason testing would also enable athletic trainers to acquire baseline data for all athletes before they are injured.



#14 The effect of volume equated 1- versus 2-day formats of Nordic hamstring exercise training on fitness in youth soccer players: A randomized controlled trial

Reference: PLoS One. 2022 Dec 29;17(12):e0277437. doi: 10.1371/journal.pone.0277437. eCollection 2022.

Authors: Jason Moran, Norodin Vali, Ben Drury, Raouf Hammami, Jamie Tallent, Helmi Chaabene, Rodrigo Ramirez-Campillo

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Summary: This randomised controlled trial examined the effect of an 8-week volume-equated programme of Nordic hamstring exercise (NHE) training, executed at frequencies of 1- or 2-days per week, on fitness (10 m and 40 m sprint, '505' change of direction [COD] and standing long jump [SLJ]) in male youth soccer players (mean age: 16.4 ± 0.81 years). Players were divided into an experimental group (n = 16) which was further subdivided into 1-day (n = 8) and 2-day (n = 8) per week training groups and a control group (n = 8). There were significant group-by-time interactions for 10-m sprint (p<0.001, η2 = 0.120, d = 2.05 [0.57 to 3.53]), 40-m sprint (p = 0.001, η2 = 0.041, d = 1.09 [-0.23 to 2.4]) and COD (p = 0.002, η2 = 0.063, d = 1.25 [-0.09 to 2.59). The experimental group demonstrated a 'very large' effect size (d = 3.02 [1.5 to 4.54]) in 10-m sprint, and 'large' effect sizes in 40-m sprint (d = 1.94 [0.98 to 2.90]) and COD (d = 1.84 [0.85 to 2.83). The control group showed no significant changes. There were no significant differences between the 1-day and 2-day training groups. In three of the four tests (40 m, COD, SLJ) the 2-day group demonstrated larger effect sizes. Ratings of perceived exertion (RPE) were significantly lower in the 2-day group (p<0.001, 3.46 [1.83 to 5.04). The NHE increases fitness in youth soccer players and there may be advantages to spreading training over two days instead of one.



#15 The relative age effect in under-17, under-20, and adult elite female soccer players

Reference: Sci Med Footb. 2023 Jan 6;1-8. doi: 10.1080/24733938.2022.2164608. Online ahead of print.

Authors: Elaine Ribeiro, Júlia Barreira, Dayse Carraco, Larissa Galatti, Martin Götze, Cesar Cavinato Cal Abad

Summary: The aim was to investigate the RAE in elite female soccer players, the absolute and relative birthdate distributions of players who disputed the Women's World Cup were assessed. Differences between observed and expected distributions were analyzed using chi-square and effect sizes. The birthdates of 1224 female soccer players were assessed in Under-17 (N = 336), Under-20 (N = 336) and adult (N = 552) categories. There was no significant RAE in adult category for different playing positions and players in general (including all playing positions per age category). There was significant RAE for midfielders and players in general with mainly small effect sizes for the U-17 and U-20. In both age categories, players born in Q1 were over-represented with the highest quartile ratio for midfielders. In regard of RAE and success defined by final ranking at the World Cup, we found no significant differences between the birthdate distributions of players who participated in either the group stages or finally the knockout phases. Coaches should consider this information to avoid bias in talent programs designed to promote and select female soccer players independently of their birthdates. Young female players should be encouraged to learn to play in different field positions before to reach high-level performance.



#16 Deconstructing stereotypes: Stature, match-playing time, and performance in elite Women's World Cup soccer

Reference: Front Sports Act Living. 2022 Dec 14;4:1067190. doi: 10.3389/fspor.2022.1067190. eCollection 2022.

Authors: Ciara N Manning, Yasuki Sekiguchi, Courteney L Benjamin, McKenna R Spaulding, Erin E Dierickx, Jayson M Spaulding, Dayshia M Davenport, Jillian R Picard-Busky, George T Chiampas, George P Nassis, Douglas J Casa

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Summary: Recruiting companies recommend elite female soccer players be ≥165 cm (5'5″) in stature. This study investigated if stature limits match-playing time and performance in elite World Cup soccer among players, positions, and countries. We hypothesized stature would not affect match-playing time or performance. Descriptive data were collected on 552 players from 2019 FIFA Women's World Cup. Odds ratios determined likelihood of starting for players <165 cm and ≥165 cm. ANOVAs compared playing time between stature groups, among positions, and between countries. Performance factors including assists, goals, attempts, corners, shots blocked, and defending blocks were reported. Independent t-tests compared differences between players (≥165 cm, < 165 cm). Data are reported, mean difference [95% confidence interval] [MD (95%CI)] and effect sizes (ES). On average, 32.3% of players were <165 cm. Of total players, no differences existed in total minutes (F = 0.98, p = 0.32), matches (F = 0.27 p = 0.59), or average minutes per match (F = 0.48, p = 0.49) between stature groups, regardless of position. No differences existed in playing time between players <165 cm and ≥165 cm among any positions (p > 0.05), or between countries (p > 0.05). Taller mid-fielders exhibited greater performance in goals, assists, attempts, shots blocked, and defending blocks (MD [95%CI] ES; assists, -0.44[-0.76,-0.11]0.59, p = 0.009; goals, -0.35[-0.69,-0.01]0.44, p = 0.047); attempts, 3.14[1.38, 4.90]0.80, p = 0.001; corners, 2.04[0.12, 3.95]0.48, p = 0.037; shots blocked, 0.96[0.40, 1.51]0.75, p = 0.001; defending blocks, 0.43[0.32,0.82]0.48, p = 0.035), however, actual differences were minimal. Our findings indicate stature does not inhibit playing and performing elite women's soccer, as nearly one-third of players were <165 cm.



#17 Sleep duration is associated with overnight changes in perceived fatigue in elite women soccer players

Reference: Sci Med Footb. 2023 Jan 1;1-8. doi: 10.1080/24733938.2022.2163511. Online ahead of print.

Authors: João Barreira, João Brito, Júlio A Costa, Pedro Figueiredo

Summary: The current study aimed to describe sleep habits and analyze the associations between sleep indices, changes in perceived fatigue (Δ Fatigue) and external training load measures in women soccer players during a 7-day training camp. Sixteen elite women soccer players (age: 25.4 ± 3.6 years; mean ± SD) from the Portuguese Women's National Team participated in the study. Sleep indices (sleep duration and efficiency) were measured using a wrist-worn accelerometer. External training loads measures were measured using GPS devices. Players also reported perceived fatigue using a Likert scale (1 - very, very low to 7 - very, very high) before and immediately after sleep. Players' within-subject coefficient of variation for sleep duration was 5.6%, and 4.6% for sleep efficiency. Individually, 8 players (50%) slept less than 7 h per night throughout the training camp, and the same number of athletes had a sleep efficiency lower than 85%. Similar values (p<0.05) were measured for sleep duration and efficiency between training and match days. A moderate negative within-subjects correlation was found between Δ Fatigue and sleep duration (adjusted for pre-sleep fatigue) [r = -0.32; 95% Confidence Interval (-0.51 - -0.08); p = 0.04]. These findings reinforce the importance of sleep in the recovery process of elite women soccer players, showing that more sleep may help to attenuate fatigue.



#18 Mental fatigue changes from regular season to play-offs in semiprofessional soccer: A comparison by training days

Reference: Scand J Med Sci Sports. 2023 Jan 5. doi: 10.1111/sms.14301. Online ahead of print.

Authors: Jesús Díaz-García, Luca Filipas, Antonio La Torre, Jorge Gómez-Rivera, Ana Rubio-Morales, Tomás García-Calvo

Summary: The main purpose was to compare by each training the mental load and fatigue reported by semiprofessional soccer players comparing between regular season phase and the play-offs. Fifty-three players (Mage = 24.59 years) for two teams participated during the 2020/21 season. Mental load was measured with a Likert questionnaire. Mental fatigue was quantified with a Visual Analogue Scale. Four trainings were recorded each week (Monday = MD+1, Wednesday = MD-4, Thursday = MD-3 and Saturday = MD-1), with a competitive match on Sunday across 10 weeks (five dates of regular season - five dates of play-offs). A Linear Mixed Model was performed with R-studio, using the training days and the competitive phase as independent variables. The influence of time played as co-variable was also checked. Results showed MD+1 as the more mentally fatiguing day in both phases, although MD-4 were the training with higher mental load reported (p = 0.001). Comparing phases, mental fatigue was significantly higher during the play-offs (p = 0.037). With regard time played, players that did not usually play showed a decrease in mental load during the play-offs. Then, we recommend coaches to use recovery strategies for mental fatigue, avoid mentally fatiguing tasks close to competition and considerer the time played as a factor which may contribute to individual differences in player mental fatigue.






The mean and peak physical demands during transitional play and high pressure activities in elite football

The aim of the present study was to establish the effect of transitional activities (TA) on physical metrics.





Effects of mental fatigue on the psychophysiological responses, kinematic profiles, and technical performance in small-sided games

The purpose of this study was to assess the effects of mental fatigue (MF) on the psychophysiological responses, kinematic profiles, and technical performance of young soccer players in small-sided games (SSGs).





Latest research in football - week 51 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Comparison among U-17, U-20, and Professional Female Soccer in the GPS Profiles during Brazilian Championships

Reference: Int J Environ Res Public Health. 2022 Dec 11;19(24):16642. doi: 10.3390/ijerph192416642.

Authors: Ronaldo Kobal, Leonardo Carvalho, Raíssa Jacob, Marcelo Rossetti, Lucas de Paula Oliveira, Everton Crivoi Do Carmo, Renato Barroso

Summary: The purpose of this study was to compare and characterize the physical demand of official matches among under-17 (U-17), under-20 (U-20), and professional (Pro) female soccer players. All matches were from the U-17, U-20, and Pro National Brazilian Championships. Fourteen Pro matches, nine U-20 matches, and four U-17 matches were analyzed. The external load was measured by the global positioning system (GPS) and the internal workload was assessed by the ratings of perceived exertion (RPE) multiplied by the duration of the match. The activity profiles measured were total distance covered (km), total sprint distance (m) (speed &gt; 18 km·h-1), number of accelerations and decelerations (between 1 and 2 m·s-2 and &gt;3 m·s-2), and top speed (km·h-1). For the analysis, we standardized all the metrics (except the top speed) by the time (in minutes) played. The Pro group presented higher sprint distances, number of accelerations and decelerations, and top speeds, compared to U-20 and U-17. There was no difference in the total distance among groups, and there was no difference in any GPS metrics between U-20 and U-17. The RPE was higher in Pro and U-17, compared to U-20; however, the workload-RPE was higher in Pro, compared to both U-17 and U-20 groups. These findings provide important information for the evolution of physical performance according to age categories in elite female soccer players.



#2 Psychosocial Predictors of Drop-Out from Organised Sport: A Prospective Study in Adolescent Soccer

Reference: Int J Environ Res Public Health. 2022 Dec 9;19(24):16585. doi: 10.3390/ijerph192416585.

Authors: Jenny Back, Andreas Stenling, Bård Erlend Solstad, Petra Svedberg, Urban Johnson, Nikos Ntoumanis, Henrik Gustafsson, Andreas Ivarsson

Summary: In recent years an increased drop-out rate in adolescents' soccer participation has been observed. Given the potentially adverse consequences of drop-out from soccer, more information about risk factors for drop-out is warranted. In the current study, Classification and Regression Tree (CRT) analysis was used to investigate demographic and motivational factors associated with an increased risk of drop-out from adolescent soccer. The results of this study indicate that older age, experiencing less autonomy support from the coach, less intrinsic motivation, being female, and lower socioeconomic status are factors associated with an increased risk of drop-out. An interpretation of the results of this study is that coaches play a central part in creating a sports context that facilitates motivation and continued soccer participation. Based on the findings of the current study we propose that soccer clubs implement theoretically informed coach education programs to help coaches adopt autonomy-supportive coaching strategies.



#3 The Three-Level Model of Factors Contributing to High-Intensity Intermittent Performance in Male Soccer Players

Reference: Int J Environ Res Public Health. 2022 Dec 7;19(24):16402. doi: 10.3390/ijerph192416402.

Authors: Juraj Pecho, Zuzana Kováčiková, Ľuboslav Šiška, Martin Mikulič, Marcel Čurgali, Lovro Štefan, Erika Zemková

Summary: High-intensity intermittent performance in soccer is widely assessed using the yo-yo intermittent recovery level 2 test (YYIR2). This test is usually associated with aerobic-anaerobic performance. However, less is known about the direct or indirect contributions of abilities, including the anaerobic component. This study aims to propose a three-level model of factors contributing to YYIR2 performance, based on the investigation of relationships with aerobic endurance, repeated-sprint ability (RSA), and the linear and change-of-direction speed and power variables. Eighteen soccer players performed the YYIR2, with a 20-m shuttle run test (20mSR), an RSA test with change-of-direction, 5-m and 20-m sprints, and a 505 test, countermovement jump, squat jump, and drop jump. The results showed a significant relationship between the YYIR2 distance and the 20mSR distance (r = 0.721, p = 0.001), as well as with the RSA test mean time (r = -0.594, p = 0.009). In the second level, the 20mSR distance performance was not associated with any of the speed and power variables. However, the RSA test mean time correlated with the 5-m sprint (r = 0.587, p = 0.010), 20-m sprint (r = 0.702, p = 0.001), and 505 test (r = 0.585 p = 0.011) performance. In the third level, the 20-m sprint time was related to the squat jump (r = -0.577 p = 0.012) and countermovement jump (r = -0.768 p &lt; 0.001) heights. In addition to aerobic endurance, this study highlights the importance of the anaerobic component in YYIR2 performance. More specifically, aerobic endurance (52%) and RSA (36%) are the main determinants of YYIR2 performance. Subsequently, the RSA performance is determined by the linear (34-49%) and change-of-direction speed (35%), while the explosive power of lower limbs contributes to sprinting performance (33-59%). Coaches should focus on the development of these abilities to improve the high-intensity intermittent performance of soccer players.



#4 The Association between Occupational Stress and Mental Health among Chinese Soccer Referees in the Early Stage of Reopening Soccer Matches during the COVID-19 Pandemic Outbreak: A Moderated Mediation Model

Reference: Int J Environ Res Public Health. 2022 Dec 13;19(24):16750. doi: 10.3390/ijerph192416750.

Authors: Zongyu Liu, Liangyu Zhao, Shuzhen Wang, Yubo Gao, Liguo Zhang

Summary: The sudden and unpredictable changes caused by the COVID-19 pandemic are a serious threat to the occupational stress and mental health of referees worldwide, which has not attracted widespread attention. The mental health of football referees has a certain influence on their job satisfaction or the accuracy of judgments. This study constructed a moderated mediation model to explore the buffer factors between occupational stress and mental health in Chinese soccer referees in the early stage of reopening soccer matches during the COVID-19 pandemic outbreak. Data from 317 Chinese soccer referees (aged 19-45) were collected through an online questionnaire in September-October 2022. Occupational stress, mental health, job burnout and perceived social support were measured, and moderated mediation model was analyzed. The results of this study showed that occupational stress was negatively correlated with mental health through the mediating effect of job burnout and the moderated effect of perceived social support after controlling for demographic variables. Specifically, the association between occupational stress and mental health was weaker when perceived social support was higher and stronger. The results demonstrate that job burnout and perceived social support played important roles in buffering the negative effects of occupational stress on the mental health of Chinese soccer referees in the early stage of reopening soccer matches during the COVID-19 pandemic outbreak. The findings provide implications for mental health interventions in soccer referees during the public health crises.



#5 Lactate Threshold and Psychomotor Fatigue Threshold in Hot Conditions: Suggestions for Soccer Players Participating in the Qatar World Cup 2022

Reference: Int J Environ Res Public Health. 2022 Dec 18;19(24):17028. doi: 10.3390/ijerph192417028.

Authors: Marek Konefał, Jan Chmura, Małgorzata Charmas, Jadwiga Kotowska, Krzysztof Błażejczyk, Paweł Chmura

Summary: The study aimed at finding relationships between lactate threshold and psychomotor fatigue threshold during incremental exercise in thermo-neutral climate conditions and conditions for the 2022 FIFA World Cup in Qatar simulated in an environmental test chamber. The study included 24 soccer players aged 21.02 ± 3.22 years old. The following procedures were performed: The incremental exercise test to mark lactate concentration-LA (mmol·l-1); Psychomotor test to determine choice reaction time; Designation of the lactate threshold (TLA) and psychomotor fatigue threshold (TPF). Climate conditions: The procedure was performed twice in the climatic chamber: (1) in thermo-neutral conditions-TNC (ambient temperature 20.5 °C and relative air humidity 58.7%), (2) after 7 days-in Qatar conditions-QC (28.5 ± 1.92 °C) and (58.7 ± 8.64%). It was confirmed that the TPF, which reflects the highest efficiency of CNS functioning, occurs at a higher running speed than the TLA. The temperature of 28.5 °C with 58.7% humidity, which is the lower limit of heat stress, causes the psychomotor fatigue threshold to appear at a lower running speed than in thermoneutral conditions. The data recorded in this work may help to understand the specificity of physiological and psychomotor reactions to various climatic conditions.



#6 Urinary Metabolomics in Young Soccer Players after Winter Training Season

Reference: Metabolites. 2022 Dec 17;12(12):1283. doi: 10.3390/metabo12121283.

Authors: Hyang-Yeon Kim, Jung-Dae Lee, Yun-Hwan Lee, Sang-Won Seo, Ho-Seong Lee, Suhkmann Kim, Kyu-Bong Kim

Summary: During the off-season, soccer players in Korea attend the winter training season (WTS) to build running stamina for the next season. For young soccer players, proper recovery time is needed to prevent injury or muscle damage. In this study, urinary metabolites in young players after 1, 5, and 10 days of the WTS were analyzed using nuclear magnetic resonance spectroscopy (NMR) combined with multivariate analysis to suggest appropriate recovery times for improving their soccer skills. After NMR analysis of the urine samples obtained from young players, 79 metabolites were identified, and each group (1, 5, or 10 days after WTS) was separated from the before the WTS group in the target profiling analysis using partial least squares-discriminant analysis (PLS-DA). Of these, 15 metabolites, including 1-methylnicotinamide, 3-indoxylsulfate, galactarate, glutamate, glycerol, histamine, methylmalonate, maltose, N-phenylacetylglycine, trimethylamine, urea, 2-hydroxybutyrate, adenine, alanine, and lactate, were significantly different than those from before the WTS and were mainly involved in the urea, purine nucleotide, and glucose-alanine cycles. In this study, most selected metabolites increased 1 day after the WTS and then returned to normal levels. However, 4 metabolites, adenine, 2-hydroxybutyrate, alanine, and lactate, increased during the 5 days of recovery time following the WTS. Based on excess ammonia, adenine, and lactate levels in the urine, at least 5 days of recovery time can be considered appropriate.



#7 Extended Energy-Expenditure Model in Soccer: Evaluating Player Performance in the Context of the Game

Reference: Sensors (Basel). 2022 Dec 14;22(24):9842. doi: 10.3390/s22249842.

Authors: Arian Skoki, Alessio Rossi, Paolo Cintia, Luca Pappalardo, Ivan Štajduhar

Summary: Every soccer game influences each player's performance differently. Many studies have tried to explain the influence of different parameters on the game; however, none went deeper into the core and examined it minute-by-minute. The goal of this study is to use data derived from GPS wearable devices to present a new framework for performance analysis. A player's energy expenditure is analyzed using data analytics and K-means clustering of low-, middle-, and high-intensity periods distributed in 1 min segments. Our framework exhibits a higher explanatory power compared to usual game metrics (e.g., high-speed running and sprinting), explaining 45.91% of the coefficient of variation vs. 21.32% for high-, 30.66% vs. 16.82% for middle-, and 24.41% vs. 19.12% for low-intensity periods. The proposed methods enable deeper game analysis, which can help strength and conditioning coaches and managers in gaining better insights into the players' responses to various game situations.



#8 Effect of Intensified Training Camp on Psychometric Status, Mood State, and Hematological Markers in Youth Soccer Players

Reference: Children (Basel). 2022 Dec 19;9(12):1996. doi: 10.3390/children9121996.

Authors: Okba Selmi, Danielle E Levitt, Ibrahim Ouergui, Bilel Aydi, Anissa Bouassida, Katja Weiss, Beat Knechtle

Summary: During training camps, training load is purposefully intensified. Intensified training loads (TL) are associated with psychological variations, increased fatigue, insufficient recovery, decreased muscular performance, and biological changes in adult athletes, but whether these changes occur during training camps in youth athletes has not been established. The aim of this study was to assess changes in psychometric status, vertical jump performance (i.e., height), and hematological markers before and after an intensive training camp in youth soccer players. In this case, 15male youth soccer players (mean ± SD: age: 14.8 ± 0.4 years; height: 172.0 ± 6.9 cm, body mass: 60.8 ± 7.9 kg; training experience: 5.2 ± 0.7 years) completed a 2-week training program consisting of 1 week of moderate TL (MT) and 1 week of intensive training camp (TC). Rate of perceived exertion (RPE), TL, monotony, strain, and psychometric status (total quality of recovery (TQR) and well-being indices (sleep, stress, fatigue, and muscle soreness) were monitored before each first daily training session across two weeks. The profile of mood states (POMS), countermovement jump (CMJ) height, and blood markers (complete blood count, urea, and creatinine) were assessed before and after TC. TL (d = 5.39, large), monotony (d = 3.03, large), strain (d = 4.38, large), and well-being index (d = 7.5, large) scores increased and TQR (d = 4.6, large) decreased during TC. The TC increased tension, fatigue, and total mood disturbance and decreased vigor (all p &lt;0.01). CMJ performance p &lt; 0.01, d = 0.52, moderate), creatinine (p &lt; 0.01, d = 1.29, large), and leukocyte concentration (p &lt; 0.01, d = 1.4, large) and granulocyte concentration (p &lt; 0.01, d = 1.93, large) increased after TC. Percentage of lymphocytes (p &lt; 0.05, d = 1.17, large) and monocytes (p &lt; 0.01, d = 1.05, large) decreased while the percentage of granulocytes (p &lt; 0.05, d = 0.86, large) increased significantly. Well-being, quality of recovery, mood, granulocyte concentration, and creatinine were all altered during the week-long intensified training camp. These results may provide coaches with valuable information about psychometric status and physiological fatigue and recovery of youth soccer players to better prescribe and adjust training loads during intensive training periods.



#9 The Effects of Soccer Specific Exercise on Countermovement Jump Performance in Elite Youth Soccer Players

Reference: Children (Basel). 2022 Nov 30;9(12):1861. doi: 10.3390/children9121861.

Authors: Max Lyons Donegan, Steven Eustace, Rhys Morris, Ryan Penny, Jason Tallis

Summary: The aims of the study were to examine the test-retest reliability of force-time (F-T) characteristics and F-T curve waveform of bilateral and unilateral countermovement jumps (CMJ) in elite youth soccer players and to evaluate the effects of competitive match-play on CMJ performance. 16 male youth soccer players completed CMJs on two separate occasions to determine reliability, and immediately pre, post and 48 h following a competitive match. Coefficient of variation (CV%), Intra-class correlation coefficient (ICC) and limits of agreement were used to assess reliability of discreate CMJ variables. Single factor repeated measures ANOVA were used to determine the effects of match play. Statistical parametric mapping was used to evaluate the repeatability of the CMJ force-time waveform and the effects of match play. Jump height had limited reliability in all three jumps and only a select few jump specific F-T variables were found to be reliable (CV &lt; 10%, ICC &gt; 0.5). Select variables were reduced immediately post game but recovered 48 h post game. The F-T curve waveform was found to be repeatable but did not differ following match-play. This study suggest that select F-T variables change following match-play and may be suitable tools to allow practitioners to detect decrements in performance. These data may help inform practitioners to use the most appropriate F-T variables to assess fatigue and recovery, with implications for performance and injury risk.



#10 Extracellular and Intracellular Concentrations of Molybdenum and Zinc in Soccer Players: Sex Differences

Reference: Biology (Basel). 2022 Nov 25;11(12):1710. doi: 10.3390/biology11121710.

Authors: Víctor Toro-Román, María Concepción Robles-Gil, Diego Muñoz, Ignacio Bartolomé, Jesús Siquier-Coll, Marcos Maynar-Mariño

Summary: Molybdenum (Mo) and zinc (Zn) play important roles in the process of adaptation to physical training. The aims of the present study were: (i) to analyze the differences in extracellular (plasma and urine) and intracellular (erythrocytes and platelets) Mo and Zn concentrations between sexes and (ii) to relate extracellular Zn concentrations with biomarkers of muscle damage and muscle mass. The present study involved 138 semi-professional soccer players divided according to sex: male (n = 68) and female (n = 70). Mo and Zn concentrations were determined by inductively coupled plasma mass spectrometry. Erythrocytes, platelets, creatine kinase (CK), and lactate dehydrogenase (LDH) values were also determined by automatic cell counter and spectrophotometric techniques. There were no sex differences in Mo and Zn intake. Male soccer players obtained higher values of erythrocytes, CK, and LDH (p &lt; 0.05), and showed higher plasma and urinary concentrations of Mo and Zn (p &lt; 0.05). Female soccer players showed relatively higher Zn concentrations in erythrocytes (p &lt; 0.05). Finally, positive correlations were observed between extracellular Zn concentrations with CK, LDH and muscle mass. Extracellular concentrations of Mo and Zn were higher in male soccer players. However, the relative concentrations of Zn in relation to the number of erythrocytes were higher in female soccer players.



#11 Primary Headaches and Physical Performance: A Professional Youth Female Soccer Team Study

Reference: Brain Sci. 2022 Dec 12;12(12):1702. doi: 10.3390/brainsci12121702.

Authors: Magdalena Kobus, Elżbieta Żądzińska, Marcos Michaelides, Koulla Parpa

Summary: The vast majority of the research on acute post-traumatic incidents in athletes focuses on migraines. Physical exercise might reduce the frequency of migraines as well as trigger a migraine attack. The objectives of the study were to evaluate primary headache prevalence in professional young female soccer players and to assess whether headaches are related to physical performance. To the best of our knowledge, this is the first study that has considered the relationship between primary headaches and physical performance assessment. The research was conducted in 19 females aged 12-17 from a professional youth soccer academy. Players completed a questionnaire about health status and then performed laboratory physical tests (e.g., cardiopulmonary tests, countermovement and squat jumps, handgrip, sit-and-reach tests). Subsequently, players were separated into a headache group and a headache-free control group. In the analysed group, eight female players (42%) suffered from primary headaches. Among the performance parameters, a significant result was found in terms of flexibility. Females from the headache group had higher results in the sit-and-reach test than females from the control group (p = 0.029). Flexibility as well as mobility in migraine patients is an area with significant potential for further investigation, as little research has been conducted to date.



#12 The Influence of a Specific Cognitive-Motor Training Protocol on Planning Abilities and Visual Search in Young Soccer Players

Reference: Brain Sci. 2022 Nov 26;12(12):1624. doi: 10.3390/brainsci12121624.

Authors: Andrea Casella, Emanuele Ventura, Francesco Di Russo

Summary: The benefits of sport activity on cognition and especially on executive function development are well-known, and in recent years, several kinds of cognitive-motor training (CMT) have been proven effective in adults and older people. Less is known about possible CMT benefits in children. This study aims to confirm the positive influence played by CMTs on specific executive functions (planning abilities and visual search) in young soccer players. Twenty-four 10-year-old athletes were recruited and randomly assigned to the experimental (Exp) and control (Con) groups of 12 players. Both groups were trained for 10 weeks, twice a week (90 min per training), following standard soccer training (technical-tactical exercises). The Exp group, during the first training session of the week, in the last 22 min, performed the experimental treatment, which consisted of a psychokinetic CMT. Both groups were examined before and after the ten-week training using the Tower of London and WISC-IV cancellation tests. Results revealed that the Exp group, following treatment, reported significantly better scores than the Con group in all the cognitive measures. We concluded that the proposed CMT is more effective than motor training alone at improving planning abilities and visual search abilities, even in children.



#13 Relationship between anatomical injury site of rectus femoris muscle strain and time taken to return to play in Japanese professional soccer players

Reference: J Orthop Surg (Hong Kong). 2022 Sep-Dec;30(3):10225536221141786. doi: 10.1177/10225536221141786.

Authors: Kengo Shimozaki, Junsuke Nakase, Kazuki Asai, Rikuto Yoshimizu, Mitsuhiro Kimura, Tomoyuki Kanayama, Yusuke Yanatori, Hiroyuki Tsuchiya

Summary: The rectus femoris has three myotendinous or myoaponeurosis junctions and causes three types of muscle strain anatomically. We aimed to investigate the anatomical injury site of the rectus femoris muscle strain in professional soccer players as well as the characteristic findings on magnetic resonance imaging (MRI) and to evaluate its relationship with the time taken to return to play at competition levels. Thirteen Japanese professional soccer players who sustained injuries to the rectus femoris were included in this study. The mechanism of injury, anatomical injury site, severity, absence of hematomas, and time taken to return to competition were evaluated. Ten patients were injured while kicking and three while sprinting. The anatomical injury site was the origin aponeurosis in two cases, intramuscular tendon in eight cases, and distal aponeurosis in three cases. The severity was one-degree in three cases and two-degree in 10 cases. Hematomas were observed in five cases. Cases with injuries caused by sprinting, two-degree injuries, or clear hematomas were associated with significantly longer periods of return to play than the other cases. Additionally, patients with distal aponeurosis-type injuries tended to take a long time to return to the competition. In rectus femoris muscle strain, it is important to evaluate the anatomical injury site, severity, and absence of hematomas on MRI. Not only the injury mechanism, a clear hematoma, and high severity but also distal aponeurosis injuries may be associated with long periods of return to play at competition levels.



#14 Knee Isokinetic Profiles and Reference Values of Professional Female Soccer Players

Reference: Sports (Basel). 2022 Dec 12;10(12):204. doi: 10.3390/sports10120204.

Authors: Isabel Brígido-Fernández, Francisco García-Muro San José, Guillermo Charneco-Salguero, José Miguel Cárdenas-Rebollo, Yolanda Ortega-Latorre, Ofelia Carrión-Otero, Luis Fernández-Rosa

Summary: Few studies have previously evaluated isokinetic parameters in female soccer players in comparison to those in males. The aim of this study was to describe normative quadriceps (Q) and hamstring (H) muscle strength values in professional female soccer players and to examine differences between dominant leg (DL) and nondominant leg (NDL). A standardized test protocol of concentric knee extension and flexion test protocol was conducted using the dynamometer isokinetic system (IsoMEd 2000). All the participants were healthy female professional soccer players from Spanish first and second division teams. Players were assessed for peak torque (PT) and maximum work (MW) values at 60°/s, 180°/s, and 240°/s. The mean difference was 7.17 (p-value = 0.0036), 4.4 (p-value = 0.0386), and 4.25 Nm (p-value = 0.0241) at speed 60°, 180°, and 240°/s, respectively. No statistically significant differences were detected for H-Q values between DL and NDL. This difference was 6.44 (p-value = 0.0449), and 5.87 J (p-value = 0.0266) at speed 60°, and 180°/s. The present study can be a tool that health professionals working with female professional soccer players in their care can use to assess and monitor a particular player.



#15 Congested Period in Professional Youth Soccer Players Showed a Different High Decelerations Profile in the Group Performance and a Specific Positional Behaviour

Reference: J Funct Morphol Kinesiol. 2022 Nov 29;7(4):108. doi: 10.3390/jfmk7040108.

Authors: Borja Muñoz-Castellanos, Alberto Rabano-Muñoz, Bernardo Requena, Luis Suarez-Arrones, Jose A Asian-Clemente

Summary: Present soccer demands are increasing in terms of running requirements and the number of matches until youth soccer players experience several periods of fixture congestion during the season. Currently, congested periods have not been extensively studied in this population. For this reason, this study aimed to compare the running demands of professional youth soccer players in congested periods according to their specific playing positions. Twenty youth players were grouped according to their position: Central Defenders (CD), Fullbacks (FB), Midfielders (MF), Wide Midfielders (WM) and Strikers (ST). A GPS system was used to monitor the players during the first (M1), second (M2) and third (M3) matches played during a congested period, measuring their total distance covered (TDC), DC 18.0-20.9 km·h-1, DC 21.0-23.9 km·h-1, DC &gt; 24.0 km·h-1, number of high accelerations (&gt;2.5 m·s-2), number of high decelerations (&lt;2.5 m·s-2) and peak speed (km·h-1). M1, M2 and M3 showed the same TDC, DC 18.0-20.9 km·h-1, DC 21.0-23.9 km·h-1, DC &gt; 24.0 km·h-1, number of high accelerations, and peak speed (p &gt; 0.05). The statistical analysis showed significant differences between M1, M2 and M3 in the decelerations recorded between M1 and M3 (p &lt; 0.05). Likewise, each position showed specific behaviours during the congested period, with all showing at least one difference in DC 18.0-20.9 km·h-1, 21.0-23.9 km·h-1 or &gt;24.0 km·h-1 between M1, M2 and M3 (p &lt; 0.05). In conclusion, coaches should pay attention to the fatigue produced by the number of high decelerations. Secondly, an individualized training protocol should be considered according to the running requirements of each position when youth professional soccer players are involved in a congested period.



#16 Exploring psychosocial risk factors for dropout in adolescent female soccer

Reference: Sci Med Footb. 2022 Dec 1;6(5):668-674. doi: 10.1080/24733938.2022.2088843.

Authors: N Viktor Gredin, Jenny Back, Urban Johnson, Petra Svedberg, Andreas Stenling, Bård Erlend Solstad, Andreas Ivarsson

Summary: We examined the manner in which age, participation in other sports, socioeconomic status, perceived sport competence, achievement goal orientations, and perceived motivational climate may interact to predict the risk of dropout among adolescent female soccer players. Self-reported data from 519 female soccer players between 10 and 19 years of age (M = 13.41, SD = 1.77) were analysed using a person-centred approach to uncover the interactions among risk factors and their relative predictability of dropout. Perceived motivational climate was identified as the main predictor, where relatively lower levels of mastery climate were associated with a higher dropout tendency (absolute risk reduction [ARR] = 12.2% ±6.1% [95% CL]). If combined with relatively lower levels of mastery climate, then relatively lower levels of perceived sport competence were related to higher dropout risks (ARR = 16.5% ±9.5%), whereas, in combination with relatively higher levels of mastery climate, then relatively lower levels of ego-orientated achievement goals were associated with higher dropout rates (ARR = 10.8% ±12.6%). Our findings afford novel insights into the interactions between, and the relative importance of, various risk factors for dropout in adolescent female soccer. This knowledge may be useful for soccer associations, clubs, and coaches when developing guidelines and strategies that aim to foster young females' sustained participation in organised soccer.



#17 Determining age-specific velocity thresholds for elite youth female soccer players

Reference: Sci Med Footb. 2022 Dec 1;6(5):581-588. doi: 10.1080/24733938.2021.1991585. Epub 2021 Oct 18.

Authors: Alice Harkness-Armstrong, Kevin Till, Naomi Datson, Stacey Emmonds

Summary: This study aimed to establish age-specific velocity thresholds for Under (U)14 and U16 elite youth female soccer players. Data was collected using 10 Hz GPS units during 50 matches from 187 players (U14 n = 89; U16 n = 98). Spectral clustering identified velocity thresholds for high-speed running (HSR), very high-speed running (VHSR), and sprinting (SPR), for 699 half-match observations (U14 n = 369; U16 n = 330). Linear mixed modelling determined youth (U14 and U16) and age-group (U14 or U16) velocity thresholds, and compared distances covered between these and existing senior thresholds. The effect of playing position and playing half on velocity thresholds was also quantified. Youth velocity thresholds of HSR (≥3.00 m·s-1), VHSR (≥4.83 m·s-1), and SPR (≥5.76 m·s-1) were estimated from the model. Age-group and playing position influenced velocity thresholds but playing half did not. Adoption of youth and age-group velocity thresholds resulted in greater distance covered at HSR, VHSR, and SPR (p < 0.001; moderate-large effect size [ES] = 0.86-1.97) compared to senior thresholds. Both age-groups covered similar distances (trivial-small ESs = 0.002-0.23) when adopting youth and age-group velocity thresholds. These youth thresholds provide an alternative to arbitrary velocity thresholds within the literature, and thresholds derived from senior players or other populations, to inform appropriate quantification and interpretation of physical data within this population.



#18 The Effects of Fixture Congestion on Injury in Professional Male Soccer: A Systematic Review

Reference: Sports Med. 2022 Dec 17;1-19. doi: 10.1007/s40279-022-01799-5. Online ahead of print.

Authors: Richard Michael Page, Adam Field, Ben Langley, Liam David Harper, Ross Julian

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Summary: Professional soccer teams are often required to compete with ≤ 4 days recovery between matches. Since congested schedules reduce recovery time between matches, players are possibly at an increased injury risk. To date, there are no published systematic reviews on the impact of match congestion on injuries during professional male soccer. The aim of this systematic review was to assess the effects of fixture congestion on injuries during professional soccer. Following pre-registration on the Open Science Framework ( ) and conforming with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, systematic searches of four electronic databases (PubMed, Scopus, SPORTDiscus, and Web of Science) were conducted by independent researchers from inception until February 2022. Articles were included if they were original articles written in English and contained relevant time-loss injury data (injury that results in unavailability for training and/or match-play) for male professional soccer players regarding periods of fixture congestion (a minimum of two matches with ≤ 4 days recovery). A total of eight articles were included in the review. Five studies identified that congested fixture schedules expose players to increased match injury incidence, although layoff duration was typically lower during congested periods. Two studies identified that training and overall injury incidence were higher during congested periods, with another study identifying a lower training injury incidence during congested periods. Injury risk is, overall, increased during fixture-congested periods; however, the layoff duration is typically shorter. The current findings have implications for practitioners regarding the management, periodisation, monitoring, and design of training and competition schedules.



#19 Elite female football players' perception of the impact of their menstrual cycle stages on their football performance. A semi-structured interview-based study

Reference: Sci Med Footb. 2022 Dec 1;6(5):616-625. doi: 10.1080/24733938.2021.2020330. Epub 2021 Dec 29.

Authors: Phoebe Read, Ritan Mehta, Craig Rosenbloom, Elena Jobson, Katrine Okholm Kryger

Summary: This study assesses how female footballers perceive how their menstrual cycle impacts their physical and psychological performance, informing future research and intervention. Semi-structured interviews, developed using piloting and peer review took place with fifteen elite female footballers from two English WSL clubs (age: 25.2 [18-33]). Data was audio recorded, transcribed verbatim, and analysed thematically using NVivo. All players (100%) perceive their menstrual cycle to negatively impact performance. Analysing 27,438 words of data revealed five themes: A) symptoms, B) preparation, C) performance, D) recovery, and E) management. Over half (53%) of players experienced decreased appetite and sleep quality prior to performance during menstruation. Competitive performance was perceived to be most negatively impacted during menses (54 references) following by the pre-menstrual stage (23 references). During menstruation, the most impacted physical performance indicators were power (93%) and fatigue (87%). Psychologically, confidence, focus, and reaction to criticism were commonly affected (66.7%). Players reported missing training (13.3%) and matches (13.3%) due to severity of impact. Recovery was affected during the pre-menstrual (26.7%) and menstrual (66.7) stages. Players self-manage symptoms using over the counter (66.7%) and prescription (26.7%) medication, some prophylactically prior to competition (46.7%). This first attempt to ascertain player perception in football exposes a clear negative impact on performance. The complex interplay of biopsychosocial and logistical factors, lack of awareness and education highlight the need for further research. Intervention is necessary and immediate initiation would be prudent, starting with simple measures such as basic self-management advice, education, and provision of sanitary products.






Effects of playing 1 vs 3 matches in a one-week period on physical performance in young soccer players

The aim of this study was to analyse the effects of playing 1 vs 3 matches in a one‑week period on physical performance in young soccer players.






The soccer season: Performance variations and evolutionary trends

In this review we examined variations and evolutionary trends in endurance-related parameters of professional players.





Latest research in football - week 50 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Aerobic and Anaerobic Fitness according to High-Intensity Interval Training Frequency in Youth Soccer Players in the Last Stage of Rehabilitation

Reference: Int J Environ Res Public Health. 2022 Nov 23;19(23):15573. doi: 10.3390/ijerph192315573.

Authors: Shuren Yan, Yonghwan Kim, Yongchul Choi

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Summary: In the last stage of rehabilitation, high-intensity interval training (HIIT) for improving physical fitness is appropriate for return-to-play; however, some youth athletes visit the rehabilitation center less frequently due to conflict with their distance to center, and academic schedule. We tested the effects of short-term low-frequency HIIT in 54 youth male soccer players, after dividing them into a low-frequency group (LFG, n = 27 players) and a high-frequency group (HFG, n = 27 players). Muscle mass and body fat were measured using a body composition test, and VO2peak and exercise duration were measured using a treadmill. Five sets of anaerobic peak power and fatigue were measured repeatedly using the Wingate test. To evaluate knee joint muscle function, 60°/s, 180°/s, and 240°/s were measured using the isokinetic muscle function equipment. HIIT sessions were conducted twice a week for LFG and five times a week for HFG for 4 weeks. In this study, Wilcoxon signed-rank test and Mann-Whitney U test were mainly used for analysis. Significant improvements in VO2peak, anaerobic peak power, and knee strength were observed after intervention in both groups (p &lt; 0.05). In the post test, there were significant differences between groups in VO2peak (LFG, 56.4 vs. HFG, 57.1 mL/kg/min; p = 0.035), exercise duration (LFG, 972.3 vs. HFG, 990.4 s; p = 0.041), Wingate anaerobic peak power 5 sets (LFG, 606.3 vs. HFG, 629.3 Watt; p = 0.039), and muscle function test 240°/s (LFG, 68.5 vs. HFG, 70.2 Jouls; p = 0.010). However, neither group showed significant changes in body composition, such as muscle mass or body fat (p &gt; 0.05). In conclusion, although it is a short-term training, the effect of HIIT was shown in the HFG as well as LFG. Although HFG improved physical fitness, significant improvement was also achieved in LFG. Therefore, in the last stage of rehabilitation, low frequency as well as high frequency HIIT would be an appropriate training method to improve physical fitness for youth soccer players.



#2 Using the Conceptual Framework for Examining Sport Teams to Understand Group Dynamics in Professional Soccer

Reference: Int J Environ Res Public Health. 2022 Nov 27;19(23):15782. doi: 10.3390/ijerph192315782.

Authors: Inmaculada González-Ponce, Jesús Díaz-García, José C Ponce-Bordón, Ruth Jiménez-Castuera, Miguel A López-Gajardo

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Summary: The aim of this study is to propose a model of the interactions of group dynamics using the conceptual framework to examine sports teams; The hypothesized model includes measures of group structure (authentic leadership, perceived justice, coaching competency, role clarity/ambiguity, and role conflict), group cohesion (cohesion and team conflict), and group processes (collective efficacy and transactive memory systems). Participants were 581 professional soccer players (M = 24.51, SD = 3.73; 356 males and 225 females) who completed a multisection questionnaire assessing group dynamics variables; The results show that coach leadership predicts coaching competency and perceived justice, and both competency and justice predict role ambiguity and role conflict. Furthermore, role ambiguity and role conflict predict group cohesion and team conflict, whereas group cohesion and team conflict both predict the transactive memory system. Finally, collective efficacy is predicted by the transactive memory system; The results suggest the importance of coach behavior (leadership, justice, and competency) and group processes to improving team functioning in a professional sports context.



#3 The Influence of a Single Instrument-Assisted Manual Therapy (IAMT) for the Lower Back on the Structural and Functional Properties of the Dorsal Myofascial Chain in Female Soccer Players: A Randomised, Placebo-Controlled Trial

Reference: J Clin Med. 2022 Nov 30;11(23):7110. doi: 10.3390/jcm11237110.

Authors: Patrick Weber, Werner Klingler, Robert Schleip, Nadine Weber, Christine Joisten

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Summary: Instrument-assisted manual therapy (IAMT) is indicated to improve flexibility, reduce pain, and induce hyperaemia locally and along myofascial chains. The underlying effects are largely unclear. This randomised, placebo-controlled pilot study aimed to gain first insights into these effects, primarily on the structural level, through ultrasonography. 67 healthy female soccer players aged 20.9 (±3.9) years were examined after right lumbar intervention (IAMT: intervention group (IG), heat application: comparison group (CG), pressure-less placebo: placebo group (PG)). Ultrasonography (absolute movement and shear motion), flexibility tests (passive straight leg raise test (PSLR), lumbar and thoracic double inclinometry), and superficial skin temperature were recorded before (t0), immediately (t1) and 45 min after the intervention (t2). IAMT decreased the absolute mobility of the superficial lamina and its shear motion to the superficial fascia compared with the PG (t1; p &lt; 0.05). PSLR improved in the IG compared with the CG (t2) and PG (t1, t2; p &lt; 0.05). The temperature increased in the IG and CG compared with the PG (t1, t2) and in the CG compared with the IG (t1; p &lt; 0.05). IAMT of the lumbar back briefly reduces absolute mobility of the superficial lamina and its shear motion to the superficial fascia, improves flexibility, and increases the temperature.



#4 Muscle Architecture, Morphology, and Mechanical and Functional Properties of Biceps Femoris Long Head in Professional Soccer Players with a Prior Healed Injured Hamstring

Reference: J Clin Med. 2022 Dec 5;11(23):7222. doi: 10.3390/jcm11237222.

Authors: Francisco Javier Nuñez, Ramona Ritzmann, Fernando Hernandez-Abad, Juan Carlos Martinez, Luis Suarez-Arrones

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Summary: The aim of the present study was to compare the fascicle length, pennation angle, muscle thickness and stiffness of the biceps femoris long head, and eccentric hamstring strength between injured dominant limbs, injured non-dominant limbs, uninjured dominant limbs and uninjured non-dominant legs in previously injured players, and between dominant and non-dominant legs in uninjured elite soccer players. Twenty elite soccer players participated in this study. Ultrasound imaging and MyotonPRO were used to determine the morphological and mechanical properties of the biceps femoris long head. Isokinetic and Nordic hamstring exercises were used to assess eccentric hamstring strength. Previously injured players showed substantially lower fascicle length and muscle thickness, and significantly higher biceps femoris long head stiffness than uninjured players, without differences between limbs. The morphological and mechanical properties of elite soccer players with hamstring injury history were different from those in uninjured players. The lack of differences between limbs showed that these values are characteristics of individual players that must be considered in the design of programs to prevent BFlh injury.



#5 The Effect of a Single Dose of Citrulline on the Physical Performance of Soccer-Specific Exercise in Adult Elite Soccer Players (A Pilot Randomized Double-Blind Trial)

Reference: Nutrients. 2022 Nov 26;14(23):5036. doi: 10.3390/nu14235036.

Authors: Eduard Bezuglov, Ryland Morgans, Artemii Lazarev, Evgeny Kalinin, Mikhail Butovsky, Evgeny Savin, Eduard Tzgoev, Bekzhan Pirmakhanov, Anton Emanov, Andrey Zholinsky, Oleg Talibov

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Summary: The purpose of this study was to evaluate the effect of a single intake of citrulline at 3 g and 6 g doses in adult elite soccer players performing sport-specific exercise. This randomized double-blind placebo-controlled study analyzed 18 soccer players from the top divisions of three European countries. Participants were randomized into three groups of six each and performed a field-based soccer-specific test for 18 min. Comparative analysis of heart rate, fatigue and post-exercise recovery was conducted. There were no statistically significant differences in most of the analyzed parameters, nor at any of the time points for lactate concentration. Players' RPE exercise test score did not reveal any differences. Neither a single intake of 3 g nor of 6 g of citrulline malate affected physical performance, subjective feelings of fatigue or post-exercise recovery in adult elite soccer players who performed a soccer-specific test.



#6 Risks of the Athletic Field Revisited: Report of Unusual Occurrences of Cardiac Arrest and Sudden Death in Professional Soccer Players

Reference: Am J Med. 2022 Dec 7;S0002-9343(22)00884-1. doi: 10.1016/j.amjmed.2022.11.014.

Authors: Jiri Bonaventura, Ethan J Rowin, Martin S Maron, Barry J Maron

Summary: Sudden deaths in competitive athletes are highly visible but potentially preventable events that generate great interest amongst the cardiovascular community and general public. Internet searches was performed using a combination of keywords and operators to produce search results for sudden death or cardiac arrest on the field in professional soccer players. We identified 35 male professional soccer players (mean age 26 ± 5 years) who experienced collapse and cardiac arrest on the field (most during matches) in Europe from December 2002 to February 2022 with 63 % in the last 6 years. Twenty-five have died on the field or later in a hospital despite cardiopulmonary resuscitation. Of the 10 survivors, eight were implanted with cardioverter-defibrillators for secondary (n=6) or primary (n=2) prevention and returned to full competition; five of the 8 required successful device therapy during matches or training. Cardiac arrest and sudden death can occur not uncommonly in professional athletes highly trained over decades and participating at an elite sports level. Our observations also underscore the importance of targeted preparticipation cardiovascular screening, and availability of external defibrillators on the playing field.



#7 The keys of pressing to gain the ball - Characteristics of defensive pressure in elite soccer using tracking data

Reference: Sci Med Footb. 2022 Dec 19;1-9. doi: 10.1080/24733938.2022.2158213. Online ahead of print.

Authors: Leander Forcher, Leon Forcher, Stefan Altmann, Darko Jekauc, Matthias Kempe

Summary: Recently, the availability of big amounts of data enables analysts to dive deeper into the constraints of performance in various team sports. While offensive analyses in football have been extensively conducted, the evaluation of defensive performance is underrepresented in this sport. Hence, the aim of this study was to analyze successful defensive playing phases by investigating the space and time characteristics of defensive pressure.Therefore, tracking and event data of 153 games of the German Bundesliga (second half of 2020/21 season) were assessed. Defensive pressure was measured in the last 10 seconds of a defensive playing sequence (time characteristic) and it was distinguished between pressure on the ball-carrier, pressure on the group (5 attackers closest to the ball), and pressure on the whole team (space characteristic). A linear mixed model was applied to evaluate the effect of success of a defensive play (ball gain), space characteristic, and time characteristic on defensive pressure.Defensive pressure is higher in successful defensive plays (14.47 ± 16.82[%]) compared to unsuccessful defensive plays (12.87 ± 15.31[%]). The characteristics show that defensive pressure is higher in areas closer to the ball (space characteristic) and the closer the measurement is to the end of a defensive play (time characteristic), which is especially true for successful defensive plays. Defensive pressure is a valuable key performance indicator for defensive play. Further, this study shows that there is an association between the pressing of the ball-carrier and areas close to the ball with the success of defensive play.



#8 Ugly side of the beautiful game: the football world cup and domestic violence

Reference: BMJ. 2022 Dec 16;379:o3021. doi: 10.1136/bmj.o3021.

Authors: Kirsty Forsdike, Leesa Hooker, Anne-Marie Laslett

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#9 Changes in body composition during the macrocycle of professional football players in relation to sports nutrition knowledge

Reference: Front Nutr. 2022 Nov 29;9:981894. doi: 10.3389/fnut.2022.981894. eCollection 2022.

Authors: Wiktoria Staśkiewicz, Elzbieta Grochowska-Niedworok, Grzegorz Zydek, Agnieszka Białek-Dratwa, Mateusz Grajek, Sylwia Jaruga-Sȩkowska, Oskar Kowalski, Marek Kardas

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Summary: Professional football players are obligated to meet the physical demands and maintain the best possible performance throughout the whole macrocycle. It is important to assess the players' nutrition knowledge, identify areas that require increased nutrition awareness and identify the impact of knowledge on changes in body composition as this can affect the players' health and performance. This study aimed to assess changes in the body composition of professional football players during the macrocycle of the spring round of the football championship and to identify the correlation between nutrition knowledge and maintaining body composition. The study included 38 football players. The players' body compositions were analyzed 6 times during the macrocycle consisting of preparatory, competitive, and transition periods using the Direct Segmental Multi-Frequency Bioelectrical Impedance Analysis method. Athletes completed the Nutrition for Sport Knowledge Questionnaire to assess their nutrition knowledge. During the preparatory period, a statistically significant negative correlation was demonstrated between the players' knowledge about the subsections of micronutrients in the diet and the dispersion of the adipose percentage tissue content (r = -0.36, p = 0.03). In the competitive period, there was a statistically significant negative correlation between the players' knowledge of sports nutrition and the dispersion of lean body mass (r = -0.46, p = 0.004), and skeletal muscle mass (r = -0.36, p = 0.03). During the transition period, a statistically significant negative correlation between the players' knowledge of weight control and the dispersion of body mass (r = -0.47, p = 0.00) and BMI values (r = -0.48, p = 0.00) was identified. The player's knowledge about the subsection of macronutrients significantly negatively correlated with the dispersion of skeletal muscle mass content (r = -0.33, p = 0.05). Nutrition knowledge has an impact on the stability of body composition during all analyzed periods: preparatory, competitive, and transition periods.




#10 Lifestyle characteristics in adolescent female football players: data from the Karolinska football Injury Cohort

Reference: BMC Sports Sci Med Rehabil. 2022 Dec 14;14(1):212. doi: 10.1186/s13102-022-00603-1.

Authors: Anne Fältström, Eva Skillgate, Nathan Weiss, Henrik Källberg, Victor Lyberg, Markus Waldén, Martin Hägglund, Martin Asker, Ulrika Tranaeus

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Summary: Normative values of lifestyle characteristics in adolescent female football players may be used by clinicians and coaches to take actions because the potential important for well-being, performance on the pitch, and risk of injury. The aim was to report descriptive characteristics of lifestyle factors in adolescent female football players and potential changes over 1 year. We included 419 adolescent competitive female football players from 12 clubs and 27 teams (age 14 ± 1 years, range 12-17 years) and 286 were followed over 1 year. The players completed an extensive questionnaire regarding demographics, football-related factors, and lifestyle factors including tobacco consumption, alcohol use, medicine intake, eating and sleeping habits, well-being, stress, coping, and passion. Baseline data are presented for the total cohort and separately for 4 age groups (12, 13, 14, and 15-17 years). 12% skipped breakfast, 8% skipped lunch and 11% used protein supplements several days per week. 16% slept less than 8 h/night, 8% had impaired sleep with daytime consequences, and 22% stated that they were tired in daily activities several days per week. 32% experienced stress some or most days/week and 24% were classified as having psychological distress. Medicine intake (23% vs. 34%), skipping breakfast or lunch several days per week (10% vs. 47% and 20 vs. 33%), tiredness (20% vs. 27%), stress (26% vs. 40%), and psychological distress (27% vs. 37%) increased significantly (P = 0.031 to < 0.001) at the 1-year follow-up. Many adolescent female football players skip breakfast and lunch, have insufficient sleep, experience stress and are classified as having psychological distress. These factors increased over 1 year.



#11 Bio-secure bubble during the COVID-19 pandemic to host the Asian Football Confederation (AFC) Champions League: A retrospective observational study

Reference: Health Sci Rep. 2022 Dec 9;6(1):e985. doi: 10.1002/hsr2.985. eCollection 2023 Jan.

Authors: AbdulWahab Abubaker Al Musleh, Mohammad Asim, Sameer Abdurahiman, Ayman El-Menyar, Naushad Ahmad Khan, Hassan Al-Thani

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Summary: The purpose was to describe the COVID-19 positivity rate among football players, team staff, and local organizing committee members participated in the Asian Football Confederation (AFC) Champions League (West) tournament organized with the Bio-secure bubble protocol in place. A retrospective observational study was carried out to include a total of 2184 participants during the AFC-West tournament in Qatar, which was a 3-week event (September 14-October 3, 2020). This event was undertaken under the Bio-secure bubble protocol, which was developed and implemented for sports events in Qatar during the pandemic. Within 72 h of departure and upon arrival in Qatar, all participants underwent reverse-transcriptase polymerase chain reaction testing (RT-PCR) to diagnose COVID-19. The test was considered positive based on the cycle threshold (cT) value which was <30, whereas, reactive if cT value was ≥30 and <40, and negative (cT > 40). Of the 2184 participants (528 players, 388 team staff, and 1268 local staff), 916 international participants were tested for COVID-19 PCR upon arrival at the Hamad International Airport, whereas the local staff (n = 1268) were tested 2 days before entering the bubble. The mean age of the players was 27.5 ± 9.8. Fifteen teams participated and as many as 60 matches were played over 3 weeks. Most participants tested negative (95.3%) and 3.9% tests were inconclusive. During the entire tournament, the positivity rate was 2.7% among all participants. Of the total positive cases, 0.8% were positive before entering the bubble system. The remaining (1.9%) tested positive during the tournament phase (19 players, 16 team officials, and 8 organizing committee staff). Bio-secure bubble protocol operated in a controlled environment presents a minimal risk of COVID-19 infection for hosting international football events. This framework could be benchmarked to resume professional football competitions under unprecedented pandemic situations.



#12 Insight into the Molecular Signature of Skeletal Muscle Characterizing Lifelong Football Players

Reference: Int J Environ Res Public Health. 2022 Nov 28;19(23):15835. doi: 10.3390/ijerph192315835.

Authors: Stefania Orrù, Esther Imperlini, Daniela Vitucci, Marianna Caterino, Annalisa Mandola, Morten Bredsgaard Randers, Jakob Friis Schmidt, Marie Hagman, Thomas Rostgaard Andersen, Peter Krustrup, Margherita Ruoppolo, Pasqualina Buono, Annamaria Mancini

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Summary: Aging and sedentary behavior are independent risk factors for non-communicable diseases. An active lifestyle and structured physical activity are positively associated with a healthier quality of life in the elderly. Here, we explored the proteomic/metabolomic muscular signature induced by lifelong football training associated with successful aging. The study was performed on nine lifelong football players (67.3 ± 2.8 yrs) and nine aged-matched untrained subjects. We performed a proteomic/metabolomic approach on V. lateralis muscle biopsies; the obtained data were analyzed by means of different bioinformatic tools. Our results indicated that lifelong football training is able to enhance the muscles' oxidative capacity in the elderly by promoting fatty acids as preferential energetic substrates and hence determining a healthier body composition and metabolic profile; furthermore, we showed that the total polyamine content is higher in lifelong football players' muscle, enforcing the involvement of polyamines in muscle growth and hypertrophy. Lifelong football training, as a structured physical activity, significantly influences the expression of the proteins and metabolites involved in oxidative metabolism and muscle hypertrophy associated with successful aging.



#13 Comparison of the External Load in Training Sessions and Official Matches in Female Football: A Case Report

Reference: Int J Environ Res Public Health. 2022 Nov 28;19(23):15820. doi: 10.3390/ijerph192315820.

Authors: Aratz Olaizola, Ibai Errekagorri, Karmele Lopez-de-Ipina, Pilar María Calvo, Julen Castellano

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Summary: The objective of this study was to compare the external load of training sessions using as a reference an official competition match in women's football in order to find if the training sessions replicate the competition demands. Twenty-two semi-professional football players were analyzed during 17 weeks in the first phase of the competitive period of the 2020-2021 season of Spanish women's football. In addition to the competition (Official Matches, OM), four types of sessions were distinguished: strength or intensity (INT), endurance or extensity (EXT), velocity (VEL), and activation or pre-competitive (PREOM). The external load variables recorded were total distance (TD), high-speed running (HSR), sprint (Sprint), accelerations (ACC2), decelerations (DEC2), player load (PL), distance covered per minute (TDmin), high metabolic load distance (HMLD), and total impacts. The main results were that the external load demanded was different according to the type of session, being, in all cases, much lower than OM. The variables referring to the neuromuscular demands (ACC2 and DEC2) were higher in the INT sessions, the TD variable in the EXT sessions and the velocity variables (HSR and Sprint) in the VEL sessions. We can conclude that there was an alternating horizontal distribution of training loads within the competitive micro-cycle in women's football, although the order was not the usual one for tactical periodization.



#14 The influence of removing home advantage on the Chinese Football Super League

Reference: BMC Sports Sci Med Rehabil. 2022 Dec 9;14(1):208. doi: 10.1186/s13102-022-00604-0.

Authors: Bo Han, Lang Yang, Pengyu Pan, Antonio García-de-Alcaraz, Can Yang, Tianbiao Liu

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Summary: Due to the COVID-19 pandemic, the 2020 season Chinese Super League (CSL) was held in neutral venues, this study aims to analyse the impact of removing home advantage (HA) in CSL. 240 games of the CSL 2019 season (home and away double round-robin system) and 160 games of the 2020 season (in neutral venues) were analysed. 27 technical and tactical performance indicators were involved as dependent variables. A multiple linear regression model was established to analyse the influence of removing HA on the performance indicators. After moving from home stadium to neutral venue in 2020 season, goal, shot, shot on target, shot from outside box, shot from inside box, shot on target from inside box, corner kick, key pass, cross, breakthrough, tackle decreased significantly (p < 0.05), while yellow card and foul increased steeply (p < 0.05). Comparing with playing away match, in neutral venue, free kicks and pass accuracy enhanced radically (p < 0.05), while tackle, clearance and block shot dropped noticeably (p < 0.05). When removing HA and playing in the neutral venue, teams' performance dropped significantly. This study confirmed the positive impact of HA on the teams' performance and may help elite football teams make proper playing strategies regarding different match locations.



#15 An Exploratory Study in Non-Professional Football on the Perception of Stakeholders about the New Working Professional Profile of Sports Kinesiologist

Reference: Int J Environ Res Public Health. 2022 Nov 28;19(23):15839. doi: 10.3390/ijerph192315839.

Authors: Gaetano Raiola, Tiziana D'Isanto, Francesca D'Elia, Gaetano Altavilla

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Summary: In Italy, recent amendments to Legislative Decree n. 36 of 28 February 2021, on sports work, may have made the application of the reform by stakeholders unclear, with the risk of generating further confusion among them. One of the most critical points concerns the possible equivalencies to the professional profile of the kinesiologist, which would be illegitimately recognized even for a different level of education, contrary to the requirements of the European qualification framework. The aim of the study was to understand the perceptions of stakeholders in the world of non-professional football regarding recent legislative provisions. A survey, divided into two sections, was administered to 112 presidents and 112 trainers of non-professional football associations of the province of Salerno. The first section presents five items common for both presidents and trainers, which seek to probe stakeholders' perceptions of the enjoyment, appropriateness, usefulness, and scientificity of kinesiologists. The second section presents five differentiated items. Validity and reliability were calculated. A chi-square analysis (χ2) was performed to test the independence within and between-subjects (trainers and presidents) on their perceptions about the new working professional profile of sports kinesiologist. From the results, it was possible to appreciate a discordance of opinion among stakeholders. Although the majority of presidents and trainers are in favour of introducing such a professional profile (p &lt; 0.05), contradictions emerge concerning the contribution the new professional profile can make in practice (p &gt; 0.05). The perceptual contradictions found among stakeholders' responses demonstrate how the complexity of recent regulatory provisions regarding possible equivalencies to the title of kinesiologist have inevitably generated further confusion among stakeholders.



#16 A survey of organizational structure and operational practices of elite youth football academies and national federations from around the world: A performance and medical perspective

Reference: Front Sports Act Living. 2022 Nov 23;4:1031721. doi: 10.3389/fspor.2022.1031721. eCollection 2022.

Authors: Warren Gregson, Christopher Carling, Antonio Gualtieri, James O'Brien, Patrick Reilly, Francisco Tavares, Daniele Bonanno, Emmanuel Lopez, Joao Marques, Lorenzo Lolli, Valter Di Salvo

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Summary: Medical and performance units are integral components of player development programmes in elite football academies. Nevertheless, the nature of the operational processes implemented by practitioners within clubs and national federations remains unexplored. The aim of the present study, therefore, was to survey elite youth professional football academies from around the world regarding the operational processes adopted by their medical and performance units. Of the 50 organizations invited, 10 national federations and 25 clubs took part in the survey resulting in a response rate of 70% (95% confidence interval, 56%-81%). The respondents represented three groups: senior club and academy management, performance, and medical staff. The majority (60%-90%) of clubs and national federations reported strategic alignment between senior and academy medical and performance units as well as between academy medical and performance units. Survey responses indicated substantial heterogeneity in the composition and number of medical and performance professionals employed in academies. The majority of respondents agreed their medical and performance departments were effective in utilizing staff knowledge and external sources of knowledge to inform their practice (56%-80%). Performance staff (40%-50%) and physiotherapists (30%-32%) were deemed most influential in injury prevention programmes. During the return-to-play process, the influence of specific practitioners in the medical and performance units was dependent upon the phase of return-to-play. Shared decision-making was common practice amongst performance and medical staff in injury prevention and return-to-play processes. Medical and performance data were generally centralized across the first team and academy in majority (50%-72%) of clubs and national federations. Data were integrated within the same data management system to a higher degree in clubs (68%) vs. national federations (40%). Research and development activity were reported for most academies (50%-72%), and generally led by the head of performance (37%) or team doctor (21%). Research activities were largely undertaken via internal staff (~100%), academic collaborations (50%-88%) and/or external consultants and industry partnerships (77%-83%) in the national federation and clubs. Collectively, these findings provide a detailed overview regarding key operational processes delivered by medical and performance practitioners working in elite football academies.






The soccer season: Performance variations and evolutionary trends

The physiological demands of soccer challenge the entire spectrum of the response capacity of the biological systems and fitness requirements of the players. In this review we examined variations and evolutionary trends in neuromuscular parameters of professional players.





Influence of Tactical Behaviour on Running in the 3 Most Successful Soccer Teams During the Season of the Spanish First Division

The purpose of this study was to analyze the influence of tactical behavior on physical performance of the three best Spanish soccer teams.







Latest research in football - week 49 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Effect of Playing Position on Return to Sport, Functional Outcomes, and Recurrence After Arthroscopic Bankart Repair in Soccer Players

Reference: Orthop J Sports Med. 2022 Nov 28;10(11):23259671221138106. doi: 10.1177/23259671221138106. eCollection 2022 Nov.

Authors: Ignacio Pasqualini, Luciano Andrés Rossi, Rodrigo Brandariz, Ignacio Tanoira, Nora Fuentes, Patrick J Denard, Maximiliano Ranalletta

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Summary: Little attention has been paid to playing position as a risk factor for recurrence after arthroscopic Bankart repair (ABR) in soccer players. The purpose was to compare return to sport, functional outcomes, and recurrence after ABR between goalkeepers and field position players in soccer. A retrospective comparative cohort study was performed in soccer players who underwent ABR between January 2017 and December 2019. The minimum clinical follow-up was 2 years. Functional outcomes included the Rowe score, visual analog scale (VAS) for pain, and shoulder-dependent sports ability measured with the Athletic Shoulder Outcome Scoring System (ASOSS). The difference between the post- and preoperative scores was calculated; rate and level of return to sport, recurrent instability, and revisions were also evaluated according to position played. A total of 70 position players and 11 goalkeepers met the study criteria. Postoperative functional outcomes were significantly improved in both groups as compared with baseline (P < .001 for both), although the position players achieved significantly greater pre- to postoperative improvement (ΔVAS, -2 vs 0 points [P = .029]; ΔRowe, 45 vs 30 points [P = .046]; ΔASOSS, 45 vs 40 points [P = .028]). While all players returned to soccer, only 55% (n = 6) of goalkeepers returned to the same level versus 93% of field players (P = .003). The overall rate of recurrent instability was 8.6% but was significantly higher among goalkeepers (27.2% vs 5.7%; P = .049), and the odds of goalkeepers having a recurrence were significantly higher than field position players (odds ratio, 8.5 [95% CI, 1.2-57.2]; P = .027). Although the results of ABR were generally favorable in all soccer players, goalkeepers had significantly worse functional outcomes, a lower rate of return to the same level of sport, and a higher recurrence rate as compared with field position players.



#2 Genetic profile in genes associated with muscle injuries and injury etiology in professional soccer players

Reference: Front Genet. 2022 Nov 16;13:1035899. doi: 10.3389/fgene.2022.1035899. eCollection 2022.

Authors: Antonio Maestro, Juan Del Coso, Millán Aguilar-Navarro, Jorge Gutiérrez-Hellín, Esther Morencos, Gonzalo Revuelta, Eva Ruiz Casares, Teresa Perucho, David Varillas-Delgado

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Summary: Many causes define injuries in professional soccer players. In recent years, the study of genetics in association with injuries has been of great interest. The purpose of this study was to examine the relationship between muscle injury-related genes, injury risk and injury etiology in professional soccer players. In a cross-sectional cohort study, one hundred and twenty-two male professional football players were recruited. AMPD1 (rs17602729), ACE (rs4646994), ACTN3 (rs1815739), CKM (rs8111989) and MLCK (rs2849757 and rs2700352) polymorphisms were genotyped by using Single Nucleotide Primer Extension (SNPE). The combined influence of the six polymorphisms studied was calculated using a total genotype score (TGS). A genotype score (GS) of 2 was assigned to the "protective" genotype for injuries, a GS of 1 was assigned to the heterozygous genotype while a GS of 0 was assigned to the "worst" genotype. Injury characteristics and etiology during the 2021/2022 season were classified following a Consensus Statement for injuries recording. The distribution of allelic frequencies in the AMPD1 and MLCK c.37885C>A polymorphisms were different between non-injured and injured soccer players (p < 0.001 and p = 0.003, respectively). The mean total genotype score (TGS) in non-injured soccer players (57.18 ± 14.43 arbitrary units [a.u.]) was different from that of injured soccer players (51.71 ± 12.82 a.u., p = 0.034). There was a TGS cut-off point (45.83 a.u.) to discriminate non-injured from injured soccer players. Players with a TGS beyond this cut-off had an odds ratio of 1.91 (95%CI: 1.14-2.91; p = 0.022) to suffer an injury when compared with players with lower TGS. In conclusion, TGS analysis in muscle injury-related genes presented a relationship with professional soccer players at increased risk of injury. Future studies will help to develop this TGS as a potential tool to predict injury risk and perform prevention methodology in this cohort of football players.



#3 Exploring the true burden of a time-loss injury: full vs partial time-loss in elite academy football (soccer)

Reference: Sci Med Footb. 2022 Dec 6. doi: 10.1080/24733938.2022.2156587. Online ahead of print.

Authors: Stella Veith, Matt Whalan, Neil Gibson, John A Sampson

Summary: In football, the number of days without full participation in training/competition is often used as a surrogate measure for time-loss (TL) caused by injury. However, injury management and return-to-play processes frequently include modified participation, which to date has only been recorded through self-reports. This study aims to demonstrate the differentiation between 'full' (no participation in team football) and 'partial' (reduced/modified participation in team football) burden. Injury and exposure data were collected from 118 male elite footballers (U13-U18) over 3 consecutive seasons according to the Football Consensus Statement. TL injury burden was calculated separately as the number of total, 'full' and 'partial' days lost per 1000 hours of exposure. Injury burden (137.2 days lost/1000h, 95% CI 133.4 - 141.0) was comprised of 23% (31.9 days lost/1000h, 95% CI 30.1 - 33.8) partial TL and 77% (105.3 days lost/1000h, 95% CI 102.0 - 108.6) full TL burden. Injuries of moderate severity (8-28 days lost) showed 40% of partial TL. TL injury incidence rate (6.6 injuries/1000h, 95% CI 5.8 - 7.5), the number of severe injuries (16%) and the distribution of TL and non-TL injuries (56% and 44%) were comparable to other reports in elite youth footballers. Almost one quarter of the TL injury burden showed that injured players were still included in some team football activities, which, for injuries with TL >7 days, was likely related to the return to play process. Therefore, reporting on partial TL provides insight into the true impact of injury on participation levels.



#4 Kidney functions adaptations of professional soccer players in response to an entire game season

Reference: An Acad Bras Cienc. 2022 Dec 5;94(suppl 3):e20211536. doi: 10.1590/0001-3765202220211536. eCollection 2022.

Authors: Rodrigo A S Peres, Irnak Marcelo Barbosa, Igor R Arouca, Karen V Paiva, Tainá B Coutinho, Victor C Tadeu, Anderson P Morales, Beatriz G Ribeiro, Natália Martins Feitosa, Cintia M DE Barros, Rodrigo N DA Fonseca, Jackson DE Souza-Menezes

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Summary: This study investigated the renal function of soccer players after an entire game-season. Thirty-five athletes recruited to play for the Macae Futebol Clube were invited for this study, of which 18 athletes completed the entire game season. Blood and 24-hour urine were collected at the beginning (Pre-Season) and the end of the game season (Post-Season). Kidney functions were assessed by calculating the urinary excretion, clearance, and fractional excretion of the selected solutes. Plasma creatinine, sodium, total protein, and osmolality were lower in the Post-Season . In contrast, plasma urea was higher in the Post-Season period. Urinary excretion of urea was reduced while albumin excretion was higher in comparison to Pre-Season. The clearances of creatinine, total proteins, and albumin were higher in the Post-Season period. In accordance, the fractional excretion of albumin increased. On the other hand, the clearance and fractional excretion of urea was lower in the Post-Season period. These results show that soccer-associated exercise throughout the entire game-season induces kidney functions adaptations that may prevent dehydration in these athletes through increased urea reabsorption to conserve water. In addition, this data corroborates to increased glomerular permeability to plasma proteins, such as albumin, that soccer players may experience.



#5 Who does not respond to injury prevention warm-up programs? A secondary analysis of trial data from neuromuscular training programs in youth basketball, soccer and physical education

Reference: J Orthop Sports Phys Ther. 2022 Dec 9;1-28. doi: 10.2519/jospt.2022.11526. Online ahead of print.

Authors: Anu M Räisänen, Jean-Michel Galarneau, Carla Berg, Paul Eliason, Lauren C Benson, Oluwatoyosi B A Owoeye, Kati Pasanen, Brent Hagel, Carolyn A Emery

Summary: The aim was to identify factors associated with non-response to neuromuscular training (NMT) warm-up programs among youth exposed to NMT warm-ups. This is a secondary analysis of youth (aged 11-18 years) in the intervention groups of four randomized controlled trials in high school basketball, youth community soccer, and junior high school physical education (PE). Youth who were exposed to NMT and who sustained an injury during the study were considered 'non-responders.' Odds ratios (OR) were based on generalized estimating equations logistic regression controlling for clustering by team/class and adjusted for age, weight, height, balance performance, injury history, sex, and sport (soccer/basketball/PE). A total of 1793 youth were included. Youth with a history of injury in the previous year had higher odds (OR=1.64 95% CI: 1.14-2.37) of injury during the study and females were more likely (OR=1.67, 95% CI: 1.21-2.31) to sustain an injury than males who were participating in NMT. Age was not associated with the odds of sustaining an injury (OR=1.10, 95% CI: 0.93-1.30). Soccer players benefited most from greater adherence, with 81% lower odds of injury (OR=0.19, 95% CI: 0.06-0.57) when completing three NMT sessions a week compared with one session per week. Factors associated with non-response to an NMT warm-up program were female sex, history of injury during the previous 12 months, and lower weekly NMT session adherence in some sports (soccer).



#6 Responses of soccer players performing repeated maximal efforts in simulated conditions of the FIFA World Cup Qatar 2022: A holistic approach

Reference: PLoS One. 2022 Dec 9;17(12):e0276314. doi: 10.1371/journal.pone.0276314. eCollection 2022.

Authors: Paweł Chmura, Hongyou Liu, Marcin Andrzejewski, Antonio Tessitore, Jerzy Sadowski, Jan Chmura, Andrzej Rokita, Wojciech Tański, Leszek Cicirko, Marek Konefał

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Summary: This study aimed to assess the capacity for repeated maximal effort (RME) of soccer players in the thermo-natural conditions (NC) and in simulated conditions for the 2022 FIFA World Cup in Qatar (QSC). Twenty-four semi-professional soccer players participated in the study. The exercise test consisted of ten 6-second maximal efforts on a cycloergometer. A 90-second passive rest interval was used. The test was performed in a Weiss Technik WK-26 climate test chamber in two different conditions: 1) thermo-neutral conditions (NC-20.5°C; 58.7% humidity); and 2) simulated conditions for the 2022 World Cup in Qatar (QSC-28.5 ± 1.92°C; 58.7 ± 8.64% humidity). Power-related, physiological, psychomotor, blood, and electrolyte variables were recorded. Results showed that (1) players achieved higher peak power (max 1607,46 ± 192,70 [W] - 3rd rep), needed less time to peak power (min 0,95 ± 0,27 [s] - 3rd rep), and had a higher fatigue slope (max 218,67 ± 59,64 [W/sek] - 7th rep) in QSC than in NC (in each repetition of study protocol); (2) between the 1st repetition and subsequent repetitions a number of significants in among physiological, blood-related, and electrolyte variables were noted, but their direction was similar in both simulated conditions (e.g. V'O2/kg 37,59 ± 3,96 vs 37,95 ± 3,17 [ml/min/kg] - 3rd rep, LAC 13,16 ± 2,61 vs 14,18 ± 3,13 [mg/dl] - 10th rep or K 4,54 ± 0,29 vs 4,79 ± 0,36 [mmol/l] - 2nd rep when compare QCS and NC respectively); (3) an 8°C of temperature difference between the climatic conditions did not significantly affect the soccer players' physical and physiological responses in RME. The study results can be used in the design of training programs aimed to increase players' physiological adaptations by simulating soccer-specific conditions of play in terms of anaerobic capacity, in particular, repetitive maximal efforts. These findings will be useful during the upcoming 2022 World Cup in Qatar and in locations where high ambient temperatures are customary.



#7 Effects of match contextual factors on internal and external load in elite Brazilian professional soccer players through the season

Reference: Sci Rep. 2022 Dec 9;12(1):21287. doi: 10.1038/s41598-022-25903-x.

Authors: Rodrigo Aquino, Rodrigo Guimarães, Geraldo Oliveira Carvalho Junior, Filipe Manuel Clemente, Tomas García-Calvo, Juan José Pulido, Hadi Nobari, Gibson Moreira Praça

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Summary: This study aimed to investigate the effects of contextual match factors (quality of opposition, match outcome, change of head coach or playing style) on internal and external load in elite Brazilian professional soccer players, considering the total and effective playing time. Twenty-two professional male outfield soccer players participated in this study (age 28.4 ± 4.9 years; height 1.78 ± 0.1 cm; body mass 72.9 ± 7.1 kg). The internal (rating of perceived exertion-based load [sRPE]) and external load (distance and accelerometry-based measures) were recorded during 38 matches, over the 2021 season of the Brazilian National 1st Division League using a global position system (10 Hz) integrated with an accelerometer (200 Hz). The main results were: (i) matches played against weak opponents presented greater values of sprinting distances compared to matches against intermediate and strong opponents; (ii) players covered greater high-intensity running distances when drawing than winning the matches; (iii) matches with assistant coaches presented higher mean speed relative to effective playing time (MSEPT) compared to coach 1 and coach 2 conditions. In addition, players covered greater MSEPT and high-acceleration in matches with coach 2 vs. coach 3; (iv) finally, small positive correlations were observed between positional attack sequences and MSTPT, total distance covered, and acceleration. Coaches and practitioners should consider these results when interpreting external load variables during elite Brazilian soccer matches.



#8 Training Practices of Football Players During the Early COVID-19 Lockdown Worldwide

Reference: Int J Sports Physiol Perform. 2022 Dec 5;1-10. doi: 10.1123/ijspp.2022-0186. Online ahead of print.

Authors: Jad Adrian Washif, Iñigo Mujika, Matthew D DeLang, João Brito, Alexandre Dellal, Thomas Haugen, Bahar Hassanmirzaei, Del P Wong, Abdulaziz Farooq, Gürhan Dönmez, Kwang Joon Kim, Juan David Peña Duque, Lewis MacMillan, Ryo Matsunaga, Alireza Rabbani, Mohamed Romdhani, Montassar Tabben, Yacine Zerguini, Piotr Zmijewski, David B Pyne, Karim Chamari

Summary: The COVID-19 lockdown challenged the training options of athletes worldwide, including players from the most popular sport globally, football/soccer. The authors explored the training practices of football players worldwide during the COVID-19 lockdown. Football players (N = 2482, 30% professional, 22% semipro, and 48% amateur) completed an online survey (May-July 2020) on their training practices before versus during lockdown (March-June 2020). Questions were related to training frequency and session duration, as well as training knowledge and attitudes. Before lockdown, more professional (87%) than semipro (67%) and amateur (65%) players trained ≥5 sessions/wk, but this proportion decreased during the lockdown to 55%, 35%, and 42%, respectively. Players (80%-87%) trained ≥60 minutes before lockdown, but this proportion decreased to 45% in professionals, 43% in amateurs, and 36% in semipros during lockdown. At home, more than two-thirds of players had training space (73%) and equipment (66%) for cardiorespiratory training, while availability of equipment for technical and strength training was <50% during lockdown. Interactions between coach/trainer and player were more frequent (ie, daily) among professional (27%) than amateur (11%) and semipro (17%) players. Training load monitoring, albeit limited, was mostly performed by fitness coaches, more so with professionals (35%) than amateurs (13%) and semipros (17%). The players' training knowledge and attitudes/beliefs toward training were relatively modest (50%-59%). COVID-19 lockdown negatively affected training practices of football players worldwide, especially amateurs and semipros, for example, in training frequency, duration, intensity, technical, recovery, and other fitness training and coaching-related aspects. During lockdown-like situations, players should be monitored closely and provided appropriate support to facilitate their training.



#9 The association between statistical shape modeling-defined hip morphology and features of early hip osteoarthritis in young adult football players: Data from the femoroacetabular impingement and hip osteoarthritis cohort (FORCe) study

Reference: Osteoarthr Cartil Open. 2022 May 20;4(3):100275. doi: 10.1016/j.ocarto.2022.100275. eCollection 2022 Sep.

Authors: M M A van Buuren, J J Heerey, A Smith, K M Crossley, J L Kemp, M J Scholes, P R Lawrenson, M G King, W P Gielis, H Weinans, C Lindner, R B Souza, J A N Verhaar, R Agricola

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Summary: The aim was to explore the relationship between radiographic hip shape and features of early hip osteoarthritis (OA) on magnetic resonance imaging (MRI) in young male and female football players without radiographic hip OA. We used baseline data from a cohort of symptomatic and asymptomatic football players aged 18-50 years. Hip shape was assessed on anteroposterior radiographs with statistical shape modeling (SSM) for men and women separately. Cartilage defects and labral tears were graded using the Scoring Hip Osteoarthritis with MRI (SHOMRI) system. We used logistic regression with generalized estimating equations to estimate associations between each hip shape variant, called shape modes, and cartilage defects or labral tears. We included 229 participants (446 hips, 77.4% male). For each sex, 15 shape modes were analyzed. In men, three shape modes were associated with cartilage defects: adjusted odds ratios (aOR) 0.75 (95%CI 0.58-0.97) per standard deviation (SD) for mode 1; 1.34 (95%CI 1.05-1.69) per SD for mode 12; and 0.61 (95%CI 0.48-0.78) per SD for mode 15; and one also with labral tears: aOR 1.30 (95%CI 1.01-1.69) per SD for mode 12. These modes generally represented variations in the femoral neck and subtypes of cam morphology, with and without pincer morphology. For women, there was no evidence for associations with the outcomes. Several hip shape variants were associated with cartilage defects on MRI in young male football players. Specifically, one subtype of cam morphology was associated with both cartilage defects and labral tears. Hip shape was not associated with early OA features in women.



#10 Alterations in biceps femoris long head fascicle length, Eccentric hamstring strength qualities and single-leg hop distance throughout the ninety minutes of TSAFT90 simulated football match

Reference: PLoS One. 2022 Dec 9;17(12):e0278222. doi: 10.1371/journal.pone.0278222. eCollection 2022.

Authors: Gokhan Yagiz, Vinay Kumar Dayala, Kevin Williams, Julian Andrew Owen, Hans-Peter Kubis

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Summary: Football matches show higher hamstring strain injuries (HSIs) than football training. The occurrence of HSIs increases in the last fifteen minutes of both halves of football matches and shows an incremental trend towards the end of the ninety minutes. This study aimed to examine football-specific fatigue-induced alterations in risk factors of the HSIs, including biceps femoris long head fascicle length via ultrasonography (BFlh FL), single-leg hop distance, hamstrings' maximal eccentric strength, and single-leg hamstring bridge test (SLHB) performance. During ninety minutes of the TSAFT90 football simulation, the BFlh FL and single-leg hop distance were measured three times (before, at half-time and after 90 minutes of simulated match-play), and maximal hamstrings eccentric strength and SLHB test scores were recorded twice (before and after simulated match-play) for both legs in physically active participants (n = 15). Maximal eccentric hamstrings' strength (dominant leg (D): p < 0.001, Hedges' (adjusted) g effect size = -0.969; non-dominant leg (ND): p < 0.001, g = -0.929) and the SLHB performance (D: p < 0.001, g = -1.249; ND: p < 0.001, g = -1.108) showed large decrements immediately after the TSAFT90 intervention. There were no significant alterations in the BFlh FL, and the single-leg hop distance. Maximal eccentric strength and the SLHB performance of hamstrings are reduced after 90 minutes of simulated football match-play. Practitioners may consider focusing on improving eccentric strength and the SLHB performance. Future studies should examine alterations in the BFlh fascicles' dynamic lengthening and shortening ability during a football match.



#11 Repetitive bout of controlled soccer heading does not alter heart rate variability metrics: A preliminary investigation

Reference: Front Neurol. 2022 Nov 25;13:980938. doi: 10.3389/fneur.2022.980938. eCollection 2022. 

Authors: Jonathan David Smirl, Dakota Peacock, Joel Stephen Burma, Alexander D Wright, Kevin J Bouliane, Jill Dierijck, Paul van Donkelaar

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Summary: There is elevated unease regarding how repetitive head impacts, such as those associated with soccer heading, contribute to alterations in brain function. This study examined the extent heart rate variability (HRV) and cardiac baroreceptor sensitivity (BRS) metrics are altered immediately following an acute bout of soccer heading.  Seven male elite soccer players (24.1 ± 1.5 years) completed 40 successful soccer headers in 20-min. The headers were performed under controlled circumstances using a soccer ball launcher located 25 meters away and using an initial ball velocity of 77.5 ± 3.7 km/h (heading condition). An accelerometer (xPatch) on the right mastoid process quantified linear/rotational head accelerations. Participants also completed sham (body contact) and control (non-contact) sessions. A three-lead ECG and finger photoplethysmography characterized short-term spontaneous HRV/cardiac BRS, before and after each condition. The SCAT3 indexed symptom scores pre-post exposures to all three conditions. During the heading condition, cumulative linear and rotational accelerations experienced were 1,574 ± 97.9 g and 313,761 ± 23,966 rad/s2, respectively. Heart rate trended toward an increase from pre- to post-heading (p = 0.063), however HRV metrics in the time-domain (ps > 0.260) and frequency-domain (ps > 0.327) as well as cardiac BRS (ps > 0.144) were not significantly changed following all three conditions. Following the heading condition, SCAT3 symptom severity increased (p = 0.030) with a trend for symptom score augmentation (p = 0.078) compared to control and sham. Whereas, symptoms as measured by the SCAT3 were induced following an acute bout of controlled soccer heading, these preliminary findings indicate they were not accompanied by alterations to autonomic function. Ultimately, this demonstrates further research is needed to understand the physiological underpinnings of alterations in brain function occurring immediately after a bout of soccer heading and how these may, over time, contribute to long-term neurological impairments.



#12 Perspectives on Postmatch Fatigue From 300 Elite European Soccer Players

Reference: Int J Sports Physiol Perform. 2022 Dec 15;1-6. doi: 10.1123/ijspp.2022-0200. Online ahead of print.

Authors: Valter Di Salvo, Daniele Bonanno, Mattia Modonutti, Andrea Scanavino, Claudio Donatelli, Fabio Pigozzi, Lorenzo Lolli

Summary: The purpose was to examine the general perspectives of elite soccer players on the time course of perceived postmatch fatigue and the influence of away matches on subjective perceptions. Adopting a cross-sectional study design, we invited 371 subjects from 14 top-division European clubs competing in the Belgian First Division A, English Premier League, French Ligue 1, Italian Serie A, Portuguese Primeira Liga, Russian Premier League, and Swiss Premier League to take part in a short survey on general issues relating to postmatch fatigue measurement and tracking in professional soccer. Three hundred male professional soccer players completed the short questionnaire. For perceptions relevant to the time course of postmatch fatigue, two-thirds of respondents (67%) indicated higher postmatch fatigue perceived 2 days (48 h) after an official competition. Among these respondents, a higher proportion of answers was observed in wide midfielders (74%), attackers (74%), and central midfielders (68%). Approximately two-thirds of respondents (63%) indicated more than usual and much more than usual perceived postmatch fatigue following away matches. For the first time, our investigation addressed practical aspects that remained unexplored and fundamental to the definition of an optimal player management process following a competition. From a practical standpoint, perspectives of individual elite soccer players substantiated the notion of implementing processes with dedicated recovery protocols within 48 hours postmatch and highlighted the need for differential strategies addressing the additional burden of away matches and travel.



#13 The effect of exercise-induced fatigue and heat exposure on soccer-specific decision-making during high-intensity intermittent exercise

Reference: PLoS One. 2022 Dec 15;17(12):e0279109. doi: 10.1371/journal.pone.0279109. eCollection 2022.

Authors: Kate J Donnan, Emily L Williams, Nicholas Stanger

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Summary: Global warming and the globalisation of sport has increased the prevalence of sports competitions being held in hot environments. However, there is currently limited research investigating the impact of the heat on soccer-specific decision-making skills during exercise reflective of the physical demands of match-play. Therefore, the effects of heat exposure on physical and soccer-specific decision-making performance, biological markers (i.e., metanephrines), appraisal (i.e., challenge vs. threat) and affective states, during prolonged high-intensity intermittent exercise were investigated. Nine well-trained male soccer players completed a 92-min cycling intermittent sprint protocol (CISP), whilst simultaneously responding to a series of soccer-specific decision-making trials at various time points, in two temperature conditions: hot (32°C, 50%rh) and temperate (18°C, 50%rh). Results showed that decision-making score (p = .030) was impaired in the hot compared to the temperate condition. There was a reduced workload in the second half during the hot condition (p = .016), which coincided with a heightened threat state (p = .007) and more unpleasant feelings (p = .008) experienced in the hot, compared to temperate, condition. Furthermore, plasma normetanephrine (NMET) was higher at half-time (p = .012) and post-CISP (p ≤ .001). Also, plasma metanephrine (MET) was higher post-CISP (p = .009) in the hot compared to temperate condition, reflecting a heightened stress response. Our findings highlight the need for practitioners to consider the detrimental effects heat exposure can have on both physical and decision-making performance when looking to facilitate performance in hot conditions.



#14 The Happiness for Italy's Victory at the European Soccer Championships Costs a "Happy Heart Syndrome"

Reference: Eur J Case Rep Intern Med. 2022 Nov 8;9(11):003572. doi: 10.12890/2022_003572. eCollection 2022.

Authors: Luca Fazzini, Maria Francesca Marchetti, Mattia Biddau, Francesca Aste, Silvia Maiani, Roberta Montisci

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Summary: Takotsubo syndrome (TTS) is usually caused by physical or emotional negative stressors. Sometimes positive emotions trigger a rare form of Takotsubo syndrome, called the "happy heart" syndrome. We discuss the management of a 52-year-old female with happy heart syndrome, the differences between these stress cardiomyopathies and the relationship with hyperthyroidism. The happy heart syndrome is less common than other stress cardiomyopathies but emergency doctors, cardiologists and all specialists in internal medicine should take into account this cardiomyopathy, which occurs in patients with previous positive emotions. It is triggered by opposite stressors to Takotsubo syndrome and sometimes it may be misdiagnosed. Beyond triggers it has some different clinical features, and the management is similar. It is a rare disease, and is therefore underdiagnosed.Everybody experiences positive emotions in life but only a small percentage develop stress cardiomyopathy. A susceptibility is needed to trigger these cardiomyopathies such as hyperthyroidism, which has to be promptly treated with an endocrinologist's help.In clinical practice it is common to diagnose stress cardiomyopathies without following up the patients. We need to follow up these patients especially looking for concomitant conditions such as hyperthyroidism or hypersympathetic activity, which could present during follow-up.



#15 Soccer player with painful toe

Reference: J Fam Pract. 2022 Oct;71(8):367-369. doi: 10.12788/jfp.0491.

Authors: Stephanie Price, Shayna Rivard

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Summary: An x-ray revealed the source of the toe nodule and the nail dystrophy.



#16 A Thirteen-Year Analysis of Facial Fractures Among Professional Soccer Players

Reference: Facial Plast Surg. 2022 Dec 12. doi: 10.1055/a-1996-7595. Online ahead of print.

Authors: Konrad M Kozlowksi, Peter A Rosston, Asher C Park, Amir A Hakimi, Leandro Socolovsky, Brian Wong

Summary: This study aims to identify the epidemiology and effects of facial fractures on return to play (RTP) in Major League Soccer (MLS) and the English Premier League (EPL). A total of 39 MLS players and 40 EPL players who sustained facial fractures from 2007-2019 were identified. Data on player demographics, the injury, and the impact of their injury on RTP were collected. Elbow-to-head was the most common mechanism of injury (20.3%). The most common fracture involved the nasal bone (48.3%). Most players (90%) RTP the same season. Players who sustained nasal fractures missed significantly fewer games (p<0.001) than those who suffered other craniofacial fractures. Players treated surgically missed significantly more games (3.21 v 0.71, p=0.006) and days (30.1 v 8.70, p=0.002) than those managed non-operatively. Significantly more EPL players who sustained facial fractures wore headgear upon RTP compared to MLS players (82% vs 56%, p<0.01). Most professional soccer players who sustain a facial fracture RTP the same season, but their recovery time can vary depending on the type of fracture, injury management, or injury severity. Our findings can help inform future craniofacial injury management as well as guidelines on player safety and fracture prevention.



#17 Epidemiology of Upper Limb Injuries in two major Brazilian Soccer Championships from 2016 to 2019

Reference: J Exp Orthop. 2022 Dec 14;9(1):120. doi: 10.1186/s40634-022-00560-1.

Authors: Ewerton Borges de Souza Lima, Gabriel Paris de Godoy, Guilherme Ladeira Osés, Paulo Henrique Schmidt Lara, Leandro Masini Ribeiro, Carlos Vicente Andreoli, Alberto de Castro Pochini, Paulo Santoro Belangero, Gustavo Gonçalves Arliani, Benno Ejnisman, Moisés Cohen

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Summary: The aim was to evaluate epidemiological data of upper limb injuries in professional athletes who participated in two major Brazilian soccer championships between 2016 and 2019. A prospective cohort study was conducted to evaluate the teams of two divisions over four seasons within the Brazilian Soccer Championship and the Paulista Soccer Championship. Clubs and their doctors were contacted to participate in the study and guided on the correct way to enter data via online platforms: Transfermarkt (Transfermarkt GmbH & Co. KG) and Survey Monkey (Momentive.AI). Demographic data, injury characteristics, and FIFA Incidence Formula were analyzed. Overall, the study analyzed 3,828 matches and 126,357 hours of play. Upper limb injuries were registered 169 times, representing 6.8% of total injuries, with a FIFA incidence of 1.34. Most lesions occurred in forward players (21.3%), the shoulder exhibited the highest number of injuries (63.3%). The player's position was related to the location on the field where the injury occurred (p < 0.001); however, there was no relationship between the type of injury and the location on the body (p > 0.001). The average time to return to play was 19.1 days (range 0-200 days) and it was longer for goalkeepers. The necessity of surgical treatment was statistically associated with additional time to return to play (p < 0.001). Shoulder injuries were the most frequent upper limb injury sustained during the two major Brazilian soccer championships. Forward players suffered the most upper limb injuries and goalkeepers experienced the longest time to return to play.



#18 Postcolonial control of Fiji soccer and the return of subjugated knowledges: From the 1970s to the 2010s

Reference: Front Sports Act Living. 2022 Nov 28;4:1005733. doi: 10.3389/fspor.2022.1005733. eCollection 2022.

Authors: Kieran E James, Henry D Tuidraki, Sheikh Ali Tanzil

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Summary: The primary aim of this article is to use Foucault's idea of subjugated knowledges to search out areas and viewpoints within Fiji soccer which are suppressed by the governing authorities. To fulfill this aim, we explore and assess, via ethnographic research, the racial and ethnic aspects of Fiji soccer, from the 1970s to the 2010s, and how cultural hegemony facilitates continued Fiji Indian control and dominance within the sport. Next, and although we note the positive dimension of Fiji Football Association's 2014 Veterans' Dinner, we suggest that some ex-Ba players were apparently discriminated against by, puzzlingly, not being invited. The regulator was also unaware of, or insensitive to, ex-players' transportation needs as some were poor or invalid. We then look at the cases of Sweats Soccer Club (SSC) and Nadi Legends Football Club (NLFC) to show how, in the face of the regulator's indifference to the financial plight of an Indigenous village club (SSC), the ex-Nadi players set up instead a self-help organization (NLFC) to assist and encourage ex-players going through hard times. The latter was a cross-ethnic group/cross-class collaboration between ex-officials and ex-players and was largely outside the regulator's sphere of interest or intent.



#19 The Moderating Role of Sociability and Social Connection for the Relationship between Soccer Participation and Teamwork Ability among Chinese College Students

Reference: Int J Environ Res Public Health. 2022 Nov 22;19(23):15441. doi: 10.3390/ijerph192315441.

Authors: Yuetao Liu, Songhui You, Zhiyuan Wang

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Summary: In order to provide empirical evidence for soccer's promotion of teamwork ability and to examine whether sociability and social connection have an effect on this promotion, we explored the relationship between soccer participation (volume, duration), teamwork ability and sociability and social connection (SSC). Using the method of stratified sampling, a questionnaire survey was carried out in four universities in Shanghai. All the respondents are undergraduate students, which include the specially recruited soccer athletes and the soccer participants from ordinary college students. The findings from this study indicate that participating in soccer can positively predict the teamwork ability of college students, and SSC can negatively moderate the effect of soccer participation on teamwork ability. The effect of soccer participation on teamwork ability was different in the collegiate soccer athletes and collegiate soccer participants groups. An important value of soccer, which is often overlooked, is the help it provides college students, who have insufficient sociability and social connections, in better integrating into the team and in improving their teamwork ability. We highly recommend that college students participate in soccer to improve their teamwork skills in study and work and to better prepare for their careers.






External and Internal Training Loads for Intensive and Extensive Tactical-Conditioning in Soccer Small Sided Games

This study aimed to investigate the external and internal training loads (ITLs; session-RPE method) of 18 elite U20 soccer players undertaking a tactical-conditioning training program with special reference to small-sided games (SSGs). 





High metabolic load distance in professional soccer according to competitive level and playing positions

This study aimed to examine the Spanish professional soccer players’ high metabolic load distance profile, comparing competitive level and playing positions.





Latest research in football - week 48 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Associations of Masticatory Muscles Asymmetry and Oral Health with Postural Control and Leg Injuries of Elite Junior Soccer Players

Reference: J Hum Kinet. 2022 Nov 8;84:21-31. doi: 10.2478/hukin-2022-0086. eCollection 2022 Oct.

Authors: Henny Solleveld, Bram Slaets, Arnold Goedhart, Luc VandenBossche

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Summary: The influence of asymmetry between masticatory muscles on postural control is still under debate and only few studies examined the impact of oral health on injury risk. The present study investigated the relationships between masticatory muscles asymmetry, oral health, postural control and the prevalence of (non-contact or traumatic) leg injuries in a sample of 144 male elite junior soccer players. sEMG of the masseter and temporal muscles was performed during maximum teeth clenching, postural control was tested by measuring sway velocity during the unipedal stance with eyes closed, while oral health and the number of leg injuries were assessed using a questionnaire. The time-1 assessment was repeated in a subgroup of 69 players after one year. Pearson and partial correlation coefficients and adjusted odds ratios (OR) were used to assess associations. Asymmetry between the masseter and temporalis muscles (AMTM, quantified as anteroposterior coefficient, APC) was associated with higher sway velocity on the dominant leg (using time-1 data partial r = -0.24, p = 0.004, using longitudinal data partial r = -0.40, p = 0.005). Higher prevalence of two or more leg injuries throughout a competitive season was associated with poor oral health (adjusted OR (95%CI) using time-1 data = 2.14 (1.02-4.46), using longitudinal data = 4.47 (1.25-15.96)). These results indicate that AMTM has a negative influence on the sway velocity of the dominant leg only, possibly because frequent balancing exercises on the non-dominant leg may counteract negative influences of AMTM. The association of oral health with leg injuries underlines the need for oral health promotion and monitoring strategies in sports.



#2 Neuromuscular characteristics of agonists and antagonists during maximal eccentric knee flexion in soccer players with a history of hamstring muscle injuries

Reference: PLoS One. 2022 Dec 1;17(12):e0277949. doi: 10.1371/journal.pone.0277949. eCollection 2022.

Authors: Ramona Ritzmann, Sarah Strütt, Ignacio Torreno, Janine Riesterer, Christoph Centner, Luis Suarez-Arrones

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Summary: Muscle strain injuries (MSIs) in the hamstrings are among the most prevalent injuries in elite soccer. We aimed to examine the relation between biomechanical maladaptation in eccentric strength and neuromuscular factors separated by their time and frequency domains. 20 elite soccer players with a previous history of unilateral MSI in the M. biceps femoris (BF) long head and 20 without MSI participated. Knee flexion torques, rate of torque development (RTD) and electromyographic signals (EMG) of the BF, the M. semitendinosus (SMT) and knee extensors were obtained during unilateral maximal eccentric knee flexions performed at slow (30°/s) and fast (120°/s) angular speeds. Root mean squares and mean power frequency (MF) was calculated. In the group with a history of MSI, reduced maximal eccentric flexion torque (slow eccentrics -8±11, p<0.05; fast eccentrics -18±13 N*m, p<0.05) and RTD (-33±28 N*m/s, p<0.05; -95±47 N*m/s, p<0.05) concomitantly occurred with diminished agonistic myoelectrical activities (-4±5% of MVC, p<0.05; -10±7% of MVC, p<0.05) and MFs (-24±13 Hz, p<0.05; -24±18 Hz, p<0.05) in the BF. Simultaneously, antagonistic myoelectric activity was elevated (+4±3% of MVC, p<0.05; +3±3% of MVC, p<0.05) in MSI affected legs as compared to unaffected legs for both eccentric contractions. Deficits in myoelectrical activity (r2 = 0.715, p<0.05; r2 = 0.601, p<0.05) and MF (r2 = 0.484, p<0.05; r2 = 0.622, p<0.05) correlated with deficits in maximal torque in the affected leg in the MSI group. Analysis of SMT demonstrated no significant differences. Positive relationships between neuromuscular deficits and the reduced eccentric strength profile underpin neuronal inhibition after MSI. This persistent involvement of dysfunctional synergist and antagonist neural hamstring function in strength weakness is of clinical relevance in sports medicine for prevention and rehabilitation.



#3 Psychophysiological Responses to a Preseason Training Camp in High-Level Youth Soccer Players

Reference: Int J Sports Physiol Perform. 2022 Dec 1;1-9.  doi: 10.1123/ijspp.2022-0179. Online ahead of print.

Authors: Ludwig Ruf, Stefan Altmann, Sascha Härtel, Sabrina Skorski, Barry Drust, Tim Meyer

Summary: This study aimed to examine the responsiveness of commonly used measurement instruments to a short training camp by examining the time course of psychophysiological responses in high-level youth soccer players. Monitoring was carried out in 14 U15 male soccer players of 1 professional youth academy. Players provided data 3 days prior to (D - 3), during (D2-D4), and 1 (D + 1) and 4 days (D + 4) after the camp: 4 items for the Short Recovery and Stress Scale (SRSS), a countermovement jump (CMJ), and a submaximal run to assess exercise heart rate and heart-rate recovery. Training load during the camp followed an alternating low-high pattern, with lower training loads on D1 and D3 and higher training loads on D2 and D4. Changes in SRSS physical performance capability, emotional balance, overall recovery, muscular stress, and overall stress were small to moderate on D3 and moderate to large on D + 1, while changes were trivial on D + 4. Some CMJ parameters related to the eccentric phase were slightly improved on D3, and these parameters were slightly impaired on D4. Changes in CMJ parameters were trivial on D + 1 and D + 4. After a moderate decrease in exercise heart rate on D3, there was a small decrease on D + 4 and a moderate increase in heart-rate recovery. Measurement instruments such as the SRSS and submaximal runs can be used to monitor acute psychophysiological responses to load, while the CMJ may provide little insight during periods of intensified training load.



#4 Body composition variations between injured and non-injured professional soccer players

Reference: Sci Rep. 2022 Dec 1;12(1):20779. doi: 10.1038/s41598-022-24609-4.

Authors: Francisco Martins, Cíntia França, Ricardo Henriques, Andreas Ihle, Krzysztof Przednowek, Adilson Marques, Hélder Lopes, Hugo Sarmento, Élvio Rúbio Gouveia

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Summary: Professional soccer is characterized by its physical demands, making players' exposure to high injury risks a growing problem. It is crucial to study the factors associated with injuries in professional soccer. This study aimed to investigate the relationship between age, body composition, and others variables related with the injury profile of professional soccer players of a specific Portuguese team. Also, it analyzed the impact of the injury profile on soccer's variations in body fat (BF%), skeletal muscle mass (SMM) and total body water (TBW) throughout the season. The sample comprised 31 male professional soccer players competing in the First Portuguese Soccer League. Older players had a higher prevalence of muscular injuries. Midfielders and forwards showed the highest number of muscular injuries during the season being quadriceps the most affected zone. Considering players' BF% [Wilks' Lambda = 0.42, F (7, 23) = 4.61, p = 0.002, r = 0.58], SMM [Wilks' Lambda = 0.59, F (6, 23) = 2.70, p = 0.039, r = 0.41] and TBW [Wilks' Lambda = 0.54, F (7, 23) = 2.80, p = 0.029, r = 0.46] there was a substantial main effect for the assessments performed throughout the season and the injury status. Age assumes relevance in explaining the injury profile. The impact of the injury profile on soccer's variations in BF%, SMM and TBW throughout the season must be analyzed considering the clinical relevance.



#5 Workloads of Different Soccer-Specific Drills in Professional Players

Reference: J Hum Kinet. 2022 Nov 8;84:135-147. doi: 10.2478/hukin-2022-000075. eCollection 2022 Oct.

Authors: Marcos Chena, José Alfonso Morcillo-Losa, María Luisa Rodríguez-Hernández, Iván Asín-Izquierdo, Beatriz Pastora-Linares, Juan Carlos Zapardiel

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Summary: Soccer is a predominantly tactical sport and, therefore, tactical training has become the most widely used strategy to improve players' performance. The objective of the present study was to assess the workload of soccer-specific drills in professional players over a two-season period in an established context. GPS technology was used to record the data. One hundred and thirty-two (n = 132) soccer-specific drills were studied and grouped by categories. The individual demands of each task were related to the individual competitive profile of each player. The level of physical demand was significantly different in relation to the specific soccer drills analysed. Total distance covered, high-speed running, and the total number of high accelerations and decelerations were significantly higher in competition than in drills used for training sessions (p < .001). The Large-Sided Games (LSG), Big-Position Games (BPG) and Position Games (PG) showed higher maximum running speed values than the rest of the exercises (p < .01). The sum of high accelerations and decelerations values was greater in the Small-Sided Games (SSG) than in BPG (p < .001), Small-Position Games (SPG) (p < .001) and Physical-Technical Circuits (PTC) (p < .001). Significant differences were observed in the exercises analysed according to the player's position. The current findings provide a detailed description of conditional demands placed on soccer players in different soccer-specific drills during training sessions, in a professional soccer context and according to their playing position, which may be helpful in the development of individualized training programs in other contexts.



#6 Differences in the Contractile Properties of the Biceps Femoris and Semitendinosus Muscles Throughout a Season in Professional Soccer Players

Reference: J Hum Kinet. 2022 Nov 8;84:74-81. doi: 10.2478/hukin-2022-0088. eCollection 2022 Oct.

Authors: Daniel Fernández-Baeza, Germán Diaz-Ureña, Cristina González-Millán

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Summary: The aim of this study was to monitor seasonal changes in the mechanical and neuromuscular characteristics of the knee flexor muscles with tensiomyography, the biceps femoris (BF) and semitendinosus (ST) muscles, of 27 soccer players. All male professional soccer players (age 25 ± 4 years) were measured at the beginning of the preseason (second week) and in the competitive season (10 weeks later). The variables contraction time (Tc) and muscle displacement (Dm) showed significant differences in some muscles, and in others they indicated a tendency to change. In general, the BF improved (more explosive and better muscle tone) and the ST worsened (slower and worse muscle tone) its values during the season. The findings of this study suggest that usual daily soccer training and weekly competition might produce antagonistic changes between the knee flexor muscles.



#7 Evaluation of the impact of hot environmental conditions on physical activity among soccer players

Reference: Eur Rev Med Pharmacol Sci. 2022 Nov;26(22):8216-8223. doi: 10.26355/eurrev_202211_30353.

Authors: W-H Liu, Z-Y Li, Y C Loh

Summary: The aim of the study was to evaluate the effect of a hot environment on several physiological variables of soccer players and suggest feasible solutions to it. The study is of prospective design, considering 66 participants comprising professional soccer players. All the participants completed the Physical Activity Readiness Questionnaire (PARQ). The participants were assigned to 3 different groups. Each group was assigned 22 participants. They were made to play in three different chambers, maintained at cool, moderate and hot temperatures. Players were made to play and various variables were determined to assess the effect of hot temperature on them. Several variables were determined including absolute and relative oxygen uptake, heart rate, minute ventilation, the blood concentration of lactate and time to get exhausted. All the variables of players who played in hot temperatures have revealed higher heart rate, ventilation and increased lactate concentration. Players in a hot environment ran out faster. The study was concluded due to the players' dehydration and physiological deteriorated factors in a hot environment, leading to poor performances and also affecting the players' health in the long run. Further, the study suggested improving the environment around the game venues.



#8 Shuttle Running Within a Small-Sided Game: Effects on Internal and External Workloads, in Young Elite Soccer Players

Reference: Int J Sports Physiol Perform. 2022 Dec 2;1-8. doi: 10.1123/ijspp.2022-0203. Online ahead of print.

Authors: Marco Panascì, Vittoria Ferrando, Ambra Bisio, Luca Filipas, Piero Ruggeri, Emanuela Faelli

Summary: The aim was to compare the effects of 2 small-sided games (SSGs), shuttle running within the bout (SSG-S) versus possession play only (SSG-P) on acute physiological and metabolic responses, perception of effort, and performance. Ten young elite male soccer players (age 18.6 [1.9] y) performed two 5vs5 SSG formats (SSG-S and SSG-P) consisting of 4 × 4 minutes with 1 minute of passive recovery between bouts, 2 times each, once a week, and in a randomized order. Heart rate, blood lactate concentration, and rating of perceived exertion were assessed as indices of internal workload. Total and relative distances, distance at moderate and high speed, distances traveled in accelerations (≥2 m·s-2) and decelerations (≤-2 m·s-2; DDEC), and average metabolic power were chosen as indices of external workload and collected with a 10-Hz portable global positioning system device. Total distance, distances traveled in acceleration, distances traveled in deceleration, average metabolic power (always P < .01 and g > 1.62-large effect), and distance at moderate speed (P = .03 and g = 0.84-large effect) were significantly higher in SSG-S than in SSG-P. Moreover, the SSG-S showed higher blood lactate concentration (P = .0001, g = 12.58-large effect) and rating of perceived exertion (P = .03, g = 1.14-large effect) values than SSG-P. No significant differences in peak heart rate, relative distance, and distance at high speed were found. Our study showed, in young competitive male soccer players, the effectiveness of an SSG format that includes shuttle running within each bout in the development of more relevant internal and external workloads. These experimental data should encourage coaches to use this new SSG regimen within the traditional weekly training program.



#9 Effects of speed, agility and quickness training programme on cognitive and physical performance in preadolescent soccer players

Reference: PLoS One. 2022 Dec 1;17(12):e0277683. doi: 10.1371/journal.pone.0277683. eCollection 2022.

Authors: Athos Trecroci, Luca Cavaggioni, Alessio Rossi, Andrea Moriondo, Giampiero Merati, Hadi Nobari, Luca Paolo Ardigò, Damiano Formenti

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Summary: The aim of the present study was to investigate the effect of a short-term (4 weeks) non-soccer-specific training programme based on speed, agility and quickness (SAQ) and a soccer-specific training programme based on small-sided games (SSG) on cognitive and physical performance in preadolescent soccer players. Twenty-one participants were randomly assigned to SAQ group (n = 11) or SSG group (n = 10). They were tested pre and post interventions on physical (5 m sprint, 20 m sprint and sprint with turns of 90°) and cognitive (inhibitory control by means of the Flanker task and perceptual speed by means of the visual search task) performances. Although no significant time x group interactions were observed, the main effect of time was significant for cognitive performance and 5 m and 20 m sprint, showing improvements after both SAQ and SSG. These findings highlight that 4 weeks of SAQ training programme induced comparable improvements in cognitive and physical performance with respect to a soccer-specific training programme based on SSG in preadolescent soccer players. Non-sport-specific activities targeting speed, agility and quickness combined with cognitive engagement (i.e., SAQ) should be useful strategies as soccer-specific activities to be included within a soccer training programme for promoting both physical and cognitive domain in preadolescent individuals.



#10 Dominant and Nondominant Leg Kinematics During Kicking in Young Soccer Players: A Cross-Sectional Study

Reference: Motor Control. 2022 Nov 29;1-11.  doi: 10.1123/mc.2022-0017. Online ahead of print.

Authors: Francesco Frontani, Marco Prenassi, Viviana Paolini, Giovanni Formicola, Sara Marceglia, Francesca Policastro

Summary: The goal of the study is to analyze the kinematics and provide an EMG analysis of the support limb during an instep kick in adolescent players. We set a video camera, two torque transducers on the knee, and EMG sensors. A sample of 16 adolescent soccer players between 10 and 12 years old performed kicks. The kinematics shows a p = .039 on frontal plane (dominant 15.4 ± 1.8, nondominant 18.8 ± 1.7); the EMG analysis shows a p = .04 on muscular activation timing for the vastus medialis. A difference between the legs on the frontal plane emerges. Moreover, a huge difference on sagittal plane between the adolescent pattern and adult pattern exists (15° in adolescent population, 40° in adult population). The result shows a greater activation of the vastus medialis in the nondominant leg; probably, in this immature pattern, the adolescents use this muscle more than necessary.



#11 Quadratus lumborum muscle strain in a youth soccer player: a case report

Reference: Radiol Case Rep. 2022 Nov 24;18(2):499-502. doi: 10.1016/j.radcr.2022.10.084. eCollection 2023 Feb.

Authors: Kota Tanaka, Hiroki Funasaki, Daisuke Kubota, Yusuke Murayama, Mitsuru Saito, Yuta Iguchi

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Summary: We report a case of quadratus lumborum muscle strain that occurred in a 16-year-old soccer player during a game. According to a video recording of the game, the injury occurred when the leg landed just after kicking the ball with the same leg while dribbling. The mechanism was suspected to be right lateral flexion of the trunk while the pelvis was simultaneously forced to tilt backward. The injury healed and he was able to return to competition 3 weeks later. This is the first report of a sports-related quadratus lumborum muscle strain.



#12 The effect of the perceived social support on mental health of Chinese college soccer players during the COVID-19 lockdown: The chain mediating role of athlete burnout and hopelessness

Reference: Front Psychol. 2022 Nov 11;13:1001020. doi: 10.3389/fpsyg.2022.1001020. eCollection 2022.

Authors: Liangyu Zhao, Zongyu Liu, Liguo Zhang

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Summary: The isolation and blockade during the COVID-19 pandemic have a great impact on the mental health of Chinese college soccer players. This study aimed to explore the effect of perceived social support on mental health of college soccer players, as well as the mediating role of athlete burnout and hopelessness during the COVID-19 lockdown. Based on a sample of 674 college soccer players from several universities in China, the study used the Perceived Social Support Scale (PSSS), Kessler Psychological Distress Scale (K10), Athlete Burnout Questionnaire (ABQ) and Beck Hopelessness Scale (BHS). The results indicated that: (1) there was a significant positive correlation between perceived social support and mental health of college soccer players; (2) the athlete burnout played a mediating role between perceived social support and mental health of college soccer players; (3) the hopelessness also played a mediating role between perceived social support and mental health of college soccer players; (4) the athlete burnout and hopelessness played a chain mediating role between perceived social support and mental health. These findings could contribute to insight into the mechanisms by which perceived social support affects the mental health of college soccer players and provide important practical guidance for protecting and promoting their mental health.



#13 Match Loads May Predict Neuromuscular Fatigue and Intermittent-Running Endurance Capacity Decrement after a Soccer Match

Reference: Int J Environ Res Public Health. 2022 Nov 21;19(22):15390. doi: 10.3390/ijerph192215390.

Authors: Diego Marqués-Jiménez, Julio Calleja-González, Iñaki Arratibel-Imaz, Nicolás Terrados

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Summary: How the match-derived load metrics relate to post-match fatigue in soccer is scarcely researched. Thus, the aim of this study was to determine the associations between soccer match-related internal and external loads, neuromuscular performance decrease and intermittent-running endurance capacity decrement immediately post-match. Vertical jump (countermovement jump), straight-line sprinting (10- and 20-m sprint), change of direction ability (T-test) and intermittent-running endurance capacity (YO-YO intermittent recovery level 2) were measured one day before and immediately after a friendly match in male soccer players. During the match, players' internal and external loads were also monitored, including heart rate-derived indices, total distance at various speed thresholds, average running velocity, maximal running velocity, number of sprints and number of accelerations and decelerations at various intensity thresholds. The results show that match-induced fatigue was reflected on neuromuscular performance and intermittent-running endurance capacity immediately post-match (p &lt; 0.05). The quantification of percentage change of match external-load metrics, particularly accelerations and decelerations, provides a useful non-invasive predictor of subsequent neuromuscular fatigue status in soccer players immediately post-match (p &lt; 0.05). However, only internal load metrics present a practical application for predicting intermittent-running endurance capacity impairment (p &lt; 0.05). In summary, internal and external load metrics may allow for predicting the extent of acute fatigue, and variability between halves may represent a valuable alternative to facilitate the analysis of match-related fatigue both for research and applied purposes.



#14 Evaluation of Neuromuscular Fatigue in a Repeat Sprint Ability, Countermovement Jump and Hamstring Test in Elite Female Soccer Players

Reference: Int J Environ Res Public Health. 2022 Nov 16;19(22):15069. doi: 10.3390/ijerph192215069.

Authors: Estrella Armada-Cortés, José A Benítez-Muñoz, Alejandro F San Juan, Javier Sánchez-Sánchez

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Summary: The straight-line run is the most frequent action in soccer goal scoring situations, and it deserves considerable attention. The objective of this study was to evaluate the neuromuscular fatigue produced by an independent repeat sprint ability (RSA) test, a countermovement jump (CMJ) and a hamstring test (HT) in elite female soccer players. Twenty-four elite female soccer players participated in the study. The evaluation protocol included hamstring and CMJ tests before an RSA test (6 × 40 m 30 s rest), and hamstring and CMJ post-tests. Significant differences were found between pre-post HT measurements in the maximum angulation of the right leg (p = 0.012 Effect Size (ES) = 0.27), and the maximum velocity was higher in the left leg after RSA (p = 0.023 ES = 0.34). CMJ height after RSA was significantly lower than before the RSA test (p &lt; 0.001 ES = 0.40). The sprint total time (SprintTT) and percentage difference (%Dif) increased throughout the RSA (p &lt; 0.001, and ES = 0.648 and ES = 0.515, respectively). In elite female soccer players, it seems that the fatigue induced by an RSA test can be assessed through the loss of CMJ height and the different performance variables extracted from the RSA itself (e.g., SprintTT, Ideal Sprint). These findings could contribute to better performance management and injury prevention for elite female soccer players.



#15 Effects of video-based training on anticipation and decision-making in football players: A systematic review

Reference: Front Hum Neurosci. 2022 Nov 10;16:945067. doi: 10.3389/fnhum.2022.945067. eCollection 2022.

Authors: Jie Zhao, Qian Gu, Shuo Zhao, Jie Mao

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Summary: The training of athletes' anticipation and decision-making skills has received increasing attention from researchers, who developed and implemented training programs to achieve this. Video-based training (VBT) has become a popular method in anticipation and decision-making skills training. However, little is known about the benefits of implementing VBT in soccer. This systematic review considered the results of studies on VBT aiming to develop decision-making and anticipation skills in football players, and analyzed its effects. Literature published up to March 2022 was systematically searched on the scientific electronic databases Web of Science, PubMed, Scopus, SportDiscus, and Google Scholar. In total, 5,749 articles were identified. After screening the records according to the set exclusion and inclusion criteria, ten articles were considered eligible, including six longitudinal studies and four acute studies. Eight of the ten included studies (80%) showed that VBT group performance in anticipation or decision-making skills was significantly better at post-test than at pre-test, as evidenced by improvements in response accuracy (RA), response times (RT), mean distance scores (MDS) and passing decision-making performance. In six studies that included the no video-based training (NVBT) group, results showed that athletes in the VBT group performed better in anticipation or decision-making skills than in the NVBT group, as evidenced by improvements in RA and RT performance. The studies used different methods for VBT, both explicit and implicit training effectively improved participants' anticipation and decision-making skills. In addition, the implementation of the "first-person" perspective (i.e., the player's perspective) and virtual reality (VR) improved the presentation of video stimuli, effectively improving anticipation and decision-making. The findings of this review suggest that VBT is beneficial in developing anticipation and decision-making judgments in football players. However, some findings were inconsistent with previous studies due to differences in intervention duration and experimental protocols, and further studies are needed. Furthermore, future research should actively seek to design appropriate retention tests and transfer tests to truly understand the benefits of VBT for athletes.



#16 Adductor Strengthening Programme is successfully adopted but frequently modified in Norwegian male professional football teams: a cross-sectional study

Reference: BMJ Open. 2022 Sep 7;12(9):e060611. doi: 10.1136/bmjopen-2021-060611.

Authors: Joakim Stensø, Thor Einar Andersen, Joar Harøy

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Summary: Groin injuries represent a substantial problem in male football, with the Adductor Strengthening Programme (ASP) being the only exercise programme demonstrated to significantly reduce the risk of groin problems. We aimed first, to use the Reach Adoption Effectiveness Implementation Maintenance (RE-AIM) framework to investigate attitudes, beliefs and behaviour to the ASP among primary delivery agents of injury prevention exercises in Norwegian male professional football teams. Second, we aimed to identify a real-world application of the ASP protocol used in a professional team setting. A descriptive cross-sectional survey, using a questionnaire designed to cover all five dimensions of the RE-AIM framework and the top two divisions of Norwegian male professional football was used. Primarily, the proportion of respondents being aware of the ASP and its effect; having adopted it; having implemented it as intended; and considering maintaining using it. Secondary, the most often used ASP modifications. Twenty-nine (91%) participants responded. All (100%) respondents were aware of the ASP and its injury preventive effect. The two most stated reasons for using the ASP were its injury preventive effect and that it does not require equipment. The ASP was adopted by all (100%) delivery agents, but only 10% used it in accordance with the original protocol. The main modifications were that the players in 72% of the teams were instructed to perform a non-progressive number of repetitions during pre-season, and in 86% of the teams instructed to perform more sets, but fewer repetitions per set, during in season. In total, 97% of the delivery agents planned to continue using the ASP. The delivery agents have positive attitudes and beliefs to the ASP, but they frequently modify it. We identified and reported a real-world application of the ASP protocol.



#17 Do Serum 25-Hydroxyvitamin D Concentrations Affect Body Composition, Physical Fitness, Bone Strength and Bone Biomarkers in Female Children and Adolescent Football Players? A One-Season Study

Reference: Int J Environ Res Public Health. 2022 Nov 21;19(22):15394. doi: 10.3390/ijerph192215394.

Authors: Gabriel Lozano-Berges, Ángel Matute-Llorente, Alejandro Gómez-Bruton, Alex González-Agüero, Germán Vicente-Rodríguez, José A Casajús

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Summary: The aim was to compare changes in body composition, physical fitness, and bone biomarkers in female children and adolescent football players with different Vitamin D levels. Twenty-two players were classified into two groups according to 25(OH)D concentrations: 11 with deficient/insufficient 25(OH)D levels (IVD; &lt;30 ng/mL) and 11 with sufficient 25(OH)D levels (SVD; ≥30 ng/mL). Body composition parameters were measured using dual-energy X-ray absorptiometry and a peripheral quantitative computed tomography scanner. The following physical fitness tests were applied: maximal isometric knee extension (MIF), long jump, 30-m sprint, and 20-m shuttle run test (VO2max). Electrochemiluminescence immunoassays were used to analyze bone biomarkers and 25(OH)D. All variables were registered at the beginning and the end of the football season. The increase in subtotal bone mineral density (BMD) was higher in players with SVD than those with IVD (p = 0.030). Only players with SVD improved their MIF of the left leg (p = 0.005); whereas, only players with IVD decreased their 30-m sprint performance (p = 0.007) and VO2max (p = 0.046). No significant between- and within-group differences were found for bone biomarkers. SVD might cause an extra improvement of subtotal BMD in female children and adolescent football players. Moreover, it seems that the 25(OH)D concentration could be an important parameter for physical fitness improvement in this population.



#18 "Football- It's in Your Blood"-Lived Experiences of Undertaking Recreational Football for Health in Older Adults

Reference: Int J Environ Res Public Health. 2022 Nov 10;19(22):14816. doi: 10.3390/ijerph192214816.

Authors: Sophie Mowle, Emma Eyre, Mark Noon, Jason Tallis, Michael J Duncan

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Summary: Physical inactivity is prevalent in older adults and contributes to age-related decline in function, health, well-being, and quality of life. Recreational football for older adults has shown promise for promoting health benefits. This study explores the lived experiences of older adults engaging in a walking and recreational football intervention and identifies factors that affect behaviours and can encourage change in this population. A purposive sample (n = 14; aged 67 ± 5 years) of the lived experiences of those participating in a recreational football intervention took part in two focus groups. The participants' responses were grouped into three-time reflecting specific points in their lives: what stopped them from playing football, what got them playing, and what is needed for them to continue playing in the future. Within each of these time points in their lives, themes were identified. The key findings and practical recommendations were that football needs to be adapted and local, that the priority to play football changes over time, and that football itself is a fundamentally intrinsic motivator; 'it's in your blood'. The findings can be used to inform future interventions, encourage participation, and advise on the best practices for key stakeholders in the physical activity domain.



#19 Effects of Fatigue Induced by Repeated Sprints on Sprint Biomechanics in Football Players: Should We Look at the Group or the Individual?

Reference: Int J Environ Res Public Health. 2022 Nov 8;19(22):14643. doi: 10.3390/ijerph192214643.

Authors: Valentin Romero, Johan Lahti, Adrián Castaño Zambudio, Jurdan Mendiguchia, Pedro Jiménez Reyes, Jean-Benoît Morin

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Summary: The aim of this study was to analyse the influence of fatigue on sprint biomechanics. Fifty-one football players performed twelve maximal 30 m sprints with 20 s recovery between each sprint. Sprint kinetics were computed from running speed data and a high-frequency camera (240 Hz) was used to study kinematic data. A cluster analysis (K-mean clustering) was conducted to classify individual kinematic adaptations. A large decrease in maximal power output and less efficiency in horizontally orienting the ground reaction force were observed in fatigued participants. In addition, individual changes in kinematic components were observed, and, according to the cluster analysis, five clusters were identified. Changes in trunk, knee, and hip angles led to an overall theoretical increase in hamstring strain for some players (Cluster 5, 20/51) but to an overall decrease for some others (Cluster 1, 11/51). This study showed that the repeated sprint ability (RSA) protocol had an impact on both kinetics and kinematics. Moreover, fatigue affected the kinematics in a different way for each player, and these individual changes were associated with either higher or lower hamstring length and thus strain.



#20 The congested International Match Calendar in football: views of 1055 professional male players

Reference: BMC Sports Sci Med Rehabil. 2022 Nov 29;14(1):200. doi: 10.1186/s13102-022-00597-w.

Authors: L Pillay, D Burgess, D C Janse van Rensburg, G M Kerkhoffs, V Gouttebarge

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Summary: The International Match Calendar congestion affects players recovery. The views of a worldwide cohort of professional football players is shared in this communication. A cross-sectional observational study recruited players through Fédération Internationale des Associations de Footballeurs Professionnel's national members. An electronic survey was shared in English, French, Italian and Spanish with 1055 players consenting and completing it anonymously in November 2021. A total of 42% of respondents believe back-to-back matches should be limited to three. Most respondents (69%) felt off or in season breaks are infringed by clubs or national teams and 83% believe regulations should protect them. A total of 55% of players believed they sustained one or more injuries due to the overload and it has affected 52% of respondents' mental state. ‡The congested International Match Calendar poses a risk to professional footballers physical and mental health. Poor recovery between matches may affect player availability and performance. Players should be represented by active players when International Match Calendar scheduling decisions are made. Administrators should seek medical guidance regarding the effects of overload on performance prior to making decisions. This study allows the opportunity for a larger national team player sample to be studied.



#21 Construct Validity and Test-Retest Reliability of Hip Load Compared With Playerload During Football-Specific Running, Kicking, and Jumping Tasks

Reference: Int J Sports Physiol Perform. 2022 Dec 1;1-8. doi: 10.1123/ijspp.2022-0194. Online ahead of print.

Authors: Erik Wilmes, Bram J C Bastiaansen, Cornelis J de Ruiter, Riemer J K Vegter, Michel S Brink, Hidde Weersma, Edwin A Goedhart, Koen A P M Lemmink, Geert J P Savelsbergh

Summary: The aim was to determine the test-retest reliability of the recently developed Hip Load metric, evaluate its construct validity, and assess the differences with Playerload during football-specific short-distance shuttle runs. Eleven amateur football players participated in 2 identical experimental sessions. Each session included 3 different shuttle runs that were performed at 2 pace-controlled running intensities. The runs consisted of only running, running combined with kicks, and running combined with jumps. Cumulative Playerload and Hip Loads of the preferred and nonpreferred kicking leg were collected for each shuttle run. Test-retest reliability was determined using intraclass correlations, coefficients of variation, and Bland-Altman analyses. To compare the load metrics with each other, they were normalized to their respective values obtained during a 54-m run at 9 km/h. Sensitivity of each load metric to running intensity, kicks, and jumps was assessed using separate linear mixed models. Intraclass correlations were high for the Hip Loads of the preferred kicking leg (.91) and the nonpreferred kicking leg (.96) and moderate for the Playerload (.87). The effects (95% CIs) of intensity and kicks on the normalized Hip Load of the kicking leg (intensity: 0.95 to 1.50, kicks: 0.36 to 1.59) and nonkicking leg (intensity: 0.96 to 1.53, kicks: 0.06 to 1.34) were larger than on the normalized Playerload (intensity: 0.12 to 0.25, kicks: 0.22 to 0.53). The inclusion of Hip Load in training load quantification may help sport practitioners to better balance load and recovery.



#22 Evaluation of the Playing Time Benefits of Foreign Players in the Big-5 European Football Leagues

Reference: J Hum Kinet. 2022 Nov 8;84:238-249. doi: 10.2478/hukin-2022-000072. eCollection 2022 Oct.

Authors: Hui Zhang, Junxian Jiang

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Summary: The aim was to explore the benefits that foreign players bring to their clubs, this study used foreign players in the Big-5 European leagues (2013/2014-2017/2018 seasons) as samples and constructed a benefit model based on playing time and game points to evaluate the contribution of foreign players to their clubs in different leagues. The results showed the following: 1) from the 2013/2014 season to the 2017/2018 season, foreign players in the Bundesliga had the highest playing time benefits (PTBs) (0.526 ± 0.012), followed by foreign players in La Liga (0.523 ± 0.014), the Premier League (0.518 ± 0.011), Serie A (0.500 ± 0.012) and Ligue 1 (0.486 ± 0.011); 2) foreign players from South America had the highest PTBs in the Big-5 leagues, while those from Africa had the lowest PTBs. However, among the different leagues, there were no significant differences in the PTBs of foreign players from the same continent; 3) PTBs of foreign players in the forward position were lower than those of foreign players in the defender position; 4) the country that produced foreign players in the Big-5 leagues with the highest total PTBs was Brazil, followed by Argentina, Spain and France. Additionally, the top 15 countries by total PTBs qualified for either the 2014 or the 2018 World Cup Final.






Analysis of the Association between Internal and External Training Load Indicators in Elite Soccer: Multiple Regression Study

The aim of this study was to identify the external training load (ETL) variables that are most influential on the session rating of perceived exertion (sRPE) during elite soccer training.






Effects of Eight-Week Circuit Training with Core Exercises on Performance in Adult Male Soccer Players

The study aims to investigate the effects of circuit training with a core exercise program on physical performance in competitive amateur soccer players.





Latest research in football - week 47 -2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Change of direction frequency off the ball: new perspectives in elite youth soccer

Reference: Sci Med Footb. 2022 Nov;6(4):473-482. doi: 10.1080/24733938.2021.1986635. Epub 2021 Oct 4.

Authors: Oliver J Morgan, Barry Drust, Jack D Ade, Mark A Robinson

Summary: The aim of this study was to investigate the frequency of change of directions (COD) and examine the influences of position, leg dominance and anthropometrics on COD in elite youth soccer match play. Twenty-four elite male English Premier League (EPL) academy players (19.0 ± 1.9 years) were individually recorded during ten competitive U18s and U23s matches. Video footage of individual players was analysed using a manual notation system to record COD frequency, direction, estimated angle and recovery time. The influences of position, anthropometrics and leg dominance were accounted for. Elite youth soccer players performed on average 305 ± 50 CODs with on average 19.2 ± 3.9 seconds of recovery. The frequency of CODs was independent of position, leg dominance, anthropometry and occurred equally between left and right direction and forwards and backwards direction. CODs were mostly ≤90° (77%) and there were significantly less CODs in the 2nd half (-29, ES = 1.23, P< 0.001). The average and peak within match demands within 15 and 5-minute periods were 49 and 62 CODs, and 16 and 25 CODs, respectively. This study is the first to illustrate COD frequencies of elite youth soccer match play, providing practitioners guidance to prepare soccer players for competitive match demands.



#2 An intervention plan for preventing and handling amateur soccer players' injuries

Reference: Niger J Clin Pract. 2022 Nov;25(11):1816-1822. doi: 10.4103/njcp.njcp_237_22.

Authors: M A Bakarman, M Tashkandi, N S Mohammed

Summary: The majority of amateur soccer players are vulnerable to soccer-related injuries and many such injuries are avoidable with an adequate education. The present study aimed to measure the impact of an intervention educational plan on improving amateur soccer players' knowledge and skills in preventing and handling soccer-related injuries. The study design is a group-clustered randomized intervention-control trial, and it was carried out in Taif city, Saudi Arabia. The "Neighborhood League of Football" players were randomly allocated to a soccer injury prevention education group (intervention group) and a control group. A predesigned and validated questionnaire was used to study the changes in knowledge and skills about soccer injuries before the intervention (response a) and after (response b). The study included 246 participants in the intervention group and 256 in the control group (n = 502). The median age was 22 years. The comparison of both groups' participants' performance showed significant differences in response b analyses and participants in the intervention group achieved significantly higher scores than the control group in total score levels (P < .0001), injury mechanisms (P < .0001), injury treatment and prevention (P < .0001), and health status (P < .034). The intervention group's scores on response b (after the educational sessions) were significantly higher than response a (before the educational sessions, P < 0.001). In multiple scales and overall score levels, intervention group participants achieved significantly higher scores than their control group counterparts. Educational assistance appears to have had a good impact on their knowledge and skills.



#3 Player Sex and Playing Surface Are Individual Predictors of Injuries in Professional Soccer Players

Reference: Pathophysiology. 2022 Oct 26;29(4):619-630. doi: 10.3390/pathophysiology29040048.

Authors: Zakariya H Nawasreh, Mohammad A Yabroudi, Ahmad A Darwish, Wesam A Debes, Khaldoon M Bashaireh

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Summary: The factors contributing to soccer injuries and their influence on the occurrence of injury are controversial and inconclusive. This study aimed to determine the association between player characteristics and playing factors with injuries in professional soccer players. One hundred and fifty-two professional soccer players completed a self-administered questionnaire that asked about demographic information and injury profile, the type of playing surface on which they sustained their injury, medical treatment, and the time lost due to soccer injury at the end of the soccer season. The injury rate was 44.74% (n = 68; males: 61.50% (n = 56), females: 19.70% (n = 12)). Players' age (OR: 1.15, 95%CI: 1.05-1.25, p &lt; 0.002) and BMI (OR: 1.21, 95%CI: 1.06-1.38, p &lt; 0.003) were significantly associated with soccer injuries. After adjusting for age and BMI, players' sex (OR: 5.39, 95%CI: 2.11-13.75, p &lt; 0.001), previous soccer injury (OR: 3.308, 95%CI: 2.307-29.920, p &lt; 0.001), and playing surfaces (OR: 11.07, 95%CI: 4.53-27.03, p &lt; 0.001) were the significant predictors of soccer injuries. Players' age, BMI, sex, previous soccer injury, and playing surface were associated with injuries among professional soccer players. Old male athletes with high BMI, previous soccer injuries, and playing on natural grass were more likely to sustain soccer injuries than young female players with low BMI who had no previous injuries and played on synthetic surfaces.



#4 The mid-term effect of Osgood-Schlatter disease on knee function in young players from elite soccer academies

Reference: Phys Sportsmed. 2022 Nov 22;1-6. doi: 10.1080/00913847.2022.2148492. Online ahead of print.

Authors: E Bezuglov, B Pirmakhanov, G Ussatayeva, A Emanov, Yu Valova, A Kletsovskiy, V Khaitin, E Usmanova, M Butovskiy, R Morgans

Summary: The aim of the study was to evaluate the effect of Osgood-Schlatter disease (OSD) on knee joint function in elite young soccer players. Our hypothesis was that knee joint function in elite young soccer players was impaired following OSD compared with soccer players with no history of OSD. In young male soccer players (n = 36) from elite academies (mean ±SD, age: age: 15,3 ± 1,7 years; height: 1,7 ± 0,06 m; weight: 63,5 ± 8 kg; BMI: 20,7 ± 2). The duration between the completion of treatment or the last complaint to the study commencement was 31 ± 19 months. The average treatment duration of OSD among study participants was 18,5 ± 12 days (95%, 14-23), and the disease most often manifested in winter and spring, 33% and 31% of cases, respectively. Soccer players with a history of OSD were statistically different in IKDC and KOOS scores when compared with soccer players with no previously reported OSD (Mann-Whitney, p < 0,0001). The soccer players with a history of OSD also use NSAIDs more frequently compared with soccer players with no history of OSD (36% vs 3% respectively). OSD among young soccer players, when symptoms resolve, continue about one month and they can return to regular training and participation in games. Wherein, the negative effects in knee joint function were significantly more likely in soccer players with previous OSD history when compared with their peers with no history of OSD. While oral non-steroidal anti-inflammatory drugs was also more widely employed in soccer players with previous OSD history. Potentially this may lead to performance deficits and disadvantages for their future careers and coaches and physicians should be informed.



#5 Maturation Stage Does Not Affect Change of Direction Asymmetries in Young Soccer Players

Reference: J Strength Cond Res. 2022 Dec 1;36(12):3440-3445. doi: 10.1519/JSC.0000000000004110. Epub 2021 Oct 7.

Authors: Nikolaos D Asimakidis, Athanasios A Dalamitros, João Ribeiro, Afroditi C Lola, Vasiliki Manou

Summary: This study examined whether the stage of biological maturation can affect interlimb asymmetries during a change of direction (COD) test. Seventy-six young soccer players were divided into 2 different groups according to their peak height velocity stage (PHV): pre-PHV (n = 45, age = 11.8 ± 1.2 years, height = 149.8 ± 9.3 cm, body mass = 43.9 ± 11.2 kg) and post-PHV (n = 31, age = 14.4 ± 0.9 years, height = 170.0 ± 4.9 cm, body mass = 61.5 ± 8.9 kg). Subjects performed a 505 test to measure the completion time in both directions and a 20-m maximum sprint test. Change of direction deficit (CODD) was used as a measure for isolating COD ability. An independent sample t-test detected no significant differences between the asymmetry index values for the 505 test completion time when the pre-PHV group and the post-PHV group were compared (-3.49 ± 2.49% vs. -3.45 ± 2.47%, effect size [ES] = 0.02, p = 0.923). Similarly, the CODD asymmetry index indicated no differences between the 2 groups (-8.21 ± 5.95% vs. -7.37 ± 5.12%, ES = 0.15, p = 0.457). A paired sample t-test revealed that the values of the CODD asymmetry index were larger than those of the 505 asymmetry index (-7.88 ± 5.61% vs. -3.49 ± 2.46%, ES = 1.09, p < 0.001). According to these results, maturational status has no influence on the interlimb asymmetries of COD ability. Furthermore, subjects showed greater asymmetry values in CODD compared with the 505 test completion time, reinforcing that the evaluation of COD asymmetries should be based on CODD. As interlimb asymmetries are not altered during the maturation process, practitioners should address abnormal COD asymmetries early on during athletes' development processes.



#6 Effects of a small-sided games training program in youth male soccer players: variations of the locomotor profile while interacting with baseline level and with the accumulated load

Reference: BMC Sports Sci Med Rehabil. 2022 Nov 23;14(1):198. doi: 10.1186/s13102-022-00595-y.

Authors: Ana Filipa Silva, Rafael Oliveira, Halil Ibrahim Ceylan, Zeki Akyildiz, Francisco Tomás González-Fernández, Hadi Nobari, Mehmet Yıldız, Sabri Birlik, Filipe Manuel Clemente

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Summary: This study aimed to (1) analyze the impact of a small-sided game training program in the locomotor profile of youth male soccer players (while interacting with the baseline level - higher and lower level); and (2) test the relationships between variation in locomotor profile and the accumulated demands in 3v3, 5v5 and match over the period of observation. The cohort lasted 3-weeks. Twenty under-17 male amateur soccer players (16.8 ± 0.41 years; experience: 6.35 ± 0.67 years) were assessed twice for their final velocity at 30-15 intermittent fitness test (VIFT), peak speed at 30-m sprint test (PSS) and anaerobic speed reserve (ASR). The PSS was estimated using a Global Positioning System, while the VIFT was estimated using the maximum level attained by the players during the test. Based on the baseline levels, the scores were standardized using the Z-score. The total score of athleticism (TSA) was calculated per player to organize the players into two groups: lower TSA and higher TSA. Over the three weeks of observation, the small-sided games of 3v3 and 5v5 and match demands were monitored using polar team pro. The heart rate responses (mean and peak), distance covered (overall and split by speed thresholds), and peak speed in these games were obtained and summed over the weeks. The repeated measures ANCOVA tested the variations (time) of the locomotor profile of players while considering the baseline as covariable and the group as a factor. The Pearson-product correlation test analyzed the relationships between variations in locomotor profile (Δ, post-baseline) and the accumulated demands in 3v3, 5v5, and match. Between-groups analysis (lower TSA vs. higher TSA) revealed no significant differences on VIFT (p = 0.915), PSS (p = 0.269), ASR (p = 0.258) and TSA score (p = 0.138). Within-group (baseline vs. post-observation) analysis revealed significant difference on VIFT (p < 0.001), PSS (p = 0.008), while no significant differences were found on ASR (p = 0.949) and TSA score (p = 0.619). Significant correlations were found between ΔPSS and match total distance (r = 0.444; p = 0.050), match Z2 (r = 0.481; p = 0.032) and match Z3 (r = 0.454; p = 0.044). Significant correlations were found between ΔTSA and match total distance (r = 0.457; p = 0.043), match Z1 (r = 0.451; p = 0.046), match Z2 (r = 0.500; p = 0.025) and match Z3 (r = 0.468; p = 0.037). Significant improvements were observed after the period of observation. However, the fitness baseline level and the accumulated training load in the small-sided games seem to have no significant impact on the observed improvements.



#7 Bout duration and number of players of soccer small-sided games affect perceived enjoyment, physiological responses, and technical-tactical performance

Reference: Sci Med Footb. 2022 Nov;6(4):503-510. doi: 10.1080/24733938.2021.2009123. Epub 2021 Dec 1.

Authors: Zouhaier Farhani, Raouf Hammami, Javier Gene-Morales, Sabri Gaied Chortane, Anissa Bouassida, Alvaro Juesas, Juan C Colado

Summary: The wim awas to compare perceived enjoyment (PE), % of heart rate peak (%HRpeak), blood lactate (La), rating of perceived exertion (RPE), and technical-tactical performance of soccer players after four-a-side (4vs4) and three-a-side (3vs3) small-sided games (SSGs) with goalkeepers. Sixteen males (20.7 ± 0.7 years; experience: 6.9 ± 1.2 years) completed and were measured after six sessions of SSGs (one twelve-minute bout (1x12), two six-minute bouts (2x6), and three four-minute bouts (3x4), both 3vs3 and 4vs4). Repeated measurements ANOVA evaluated significant differences (p ≤ 0.05). There was higher PE for 1 × 12 compared to 2 × 6 (effect sizes [ES] = 1.53 [3vs3 and 4vs4]) and 3 × 4 (ES = 3.13 [4vs4] and 4.16 [3vs3]). Continuous bout duration (1x12) was characterized by a significantly greater percentage of successful passes compared to 2 × 6 (ES = 2.57 [4vs4] and 1.79 [3vs3]) and 3 × 4 (ES = 2.14 [4vs4] and 1.73 [3vs3]), and minor ball loss rate (2x6: ES = 2.14 [4vs4] and 1.11 [3vs3]; 3x4: ES = 2.11 [4vs4] and 1.57 [3vs3]). The percentage of successful tackles was only significantly greater for 1 × 12 in 4vs4 (ES = 0.83 [2x6] and 0.86 [3x4]) and successful duels in 3vs3 (ES = 1.41 [2x6] and 1.43 [3x4]). Significantly greater %HRpeak for 1 × 12 compared to 2 × 6 (ES = 1.02 [4vs4] and 0.81 [3vs3]) and 3 × 4 (ES = 1.04 [4vs4] and 0.99 [3vs3]) was observed, La differences were only significant in 3vs3 (ES = 1.60 [2x6] and 1.30 [3x4]). Greatest RPE were encountered in 3 × 4 (4vs4) and 1 × 12 and 3 × 4 (3vs3). Significant differences existed between the 3vs3 and 4vs4 designs with a non-clear pattern of better results for neither of both. Therefore, coaches should consider longer continuous bouts when programming SSGs-based training to significantly increase PE, technical-tactical performance, and training load.



#8 Team's Average Acute:Chronic Workload Ratio Correlates with Injury Risk in NCAA Men's Soccer Team

Reference: PM R. 2022 Nov 21. doi: 10.1002/pmrj.12923. Online ahead of print.

Authors: David R Bakal, Tyler R Friedrich, Gerald Keane, Brian White, Eugene Y Roh

Summary: Research in multiple sports has shown that an individual's acute:chronic workload ratio (ACWR) correlates with injury. However, tailoring team trainings to each individual's ACWR is technically challenging, and has not been found to decrease injury risk. We aimed to establish a more feasible method of utilizing the ACWR for injury prevention in soccer. In an NCAA men's soccer team, we assessed whether the team's average ACWR, as opposed to that of each individual, correlated with injuries sustained throughout the season. Injury and workload data were retrospectively evaluated for all players (n=23) of an NCAA men's soccer team during one 18-week season. Workload data for 5 GPS-derived workload variables (total distance, high-speed distance, accelerations, player load, and average velocity) were used to calculate the team's average daily acute and chronic workloads (accumulated load for each variable during the past 3 and 28 days, respectively), and uncoupled ACWRs (acute workload divided by chronic workload for each variable). A retrospective cohort design was used to compare the team's workloads and ACWRs on days where ≥1 injury occurred versus days where 0 injuries occurred using binary logistic regression models. Trainings/games with injuries had higher acute workloads, lower chronic workloads, and higher ACWRs for all 5 workload variables. In multivariable analysis, risk factors for injury included a low chronic workload for total distance (OR 7.23, p=0.024) and an ACWR >1.4 for accelerations (OR 4.34, p=0.029). The team's injury risk was greater with low distance accumulation during the chronic period, and with an elevated ACWR for accelerations. Future intervention-based studies aimed at using ACWR load-management principles as a method of decreasing injury risk in soccer can consider tracking the team's average values with the goal of maintaining a consistent chronic workload for total distance and avoiding elevations in the ACWR for accelerations. This article is protected by copyright. All rights reserved.



#9 Peak Height Velocity Affects Injury Burden in Circa-PHV Soccer Players

Reference: Int J Sports Med. 2022 Nov 21. doi: 10.1055/a-1983-6762. Online ahead of print.

Authors: Xabier Monasterio, Susana M Gil, Iraia Bidaurrazaga-Letona, Jose A Lekue, Gontzal Diaz-Beitia, Juan M Santisteban, Dae-Jin Lee, Lore Zumeta-Olaskoaga, Imanol Martin-Garetxana, Jon Larruskain

Summary: Growth and maturation are potential risk factors for soccer injuries. This research sought to describe how peak height velocity (PHV) affects overall and specific injury burden in circa- and post-PHV elite academy soccer players. Injuries and growth data collected from 2000-2020 were retrospectively studied. Longitudinal height records for 124 players were fitted with the Super-Imposition by Translation and Rotation model to calculate PHV (cm/year) and age at PHV. Players were classified according to PHV percentile (fast: ≥75th; average: 25-75th; slow: ≤25th) and maturity status (circa- or post-PHV). Overall and specific injury burden (days lost/player-season) and rate ratios for comparisons between groups were calculated based on zero-inflated negative binomial models. Confidence intervals were calculated at the 95% confidence level (CI) and the significance level was set at <0.05. In circa-PHV, players with fast PHV had 2.6 (CI: 1.4-4.8)- and 3.3 (CI:1.3-6.7)-times higher overall burden and 2.9 (CI:1.1-7.1)- and 4.1 (CI: 1.4-15.2)-times higher for growth-related injury burden compared to players with average and slow PHV, respectively. Regular monitoring of growth seems important to detect players at higher risk for being disrupted by growth-related injuries.



#10 Ultrasound-Guided Percutaneous Needle Electrolysis Combined With Therapeutic Exercise May Add Benefit in the Management of Soleus Injury in Female Soccer Players: A Pilot Study

Reference: J Sport Rehabil. 2022 Nov 21;1-7. doi: 10.1123/jsr.2022-0021. Online ahead of print.

Authors: Blanca De-la-Cruz-Torres, Beatriz Romero-Rodríguez, Carlos Romero-Morales

Summary: The performance of sprints during male soccer matches usually is slow medium paced, where the soleus and gastrocnemius (ankle plantar flexors) play a very important role. As in male soccer, soleus injuries should be considered in female soccer; but the scientific evidence is very limited in this case. The aim was to determine whether adding an ultrasound-guided percutaneous needle electrolysis (US-guided PNE) technique to a specific exercise program improved perceived pain at stretching and at palpation, ankle dorsiflexion range of motion, muscle fatigue, and sport performance in women soccer players with soleus injury. This pilot study recruited 20 female players with chronic soleus injury (type 1, characterized by hypoechoic image) who were assigned to one of 2 groups: an experimental group (exercise program + US-guided PNE; n = 10) or a control group (exercise program + sham stimulation; n = 10). Pain intensity, dorsiflexion range of motion, knee-flexion heel raise test, curve sprint test, and the global rating of change scale were analyzed at baseline and after treatment (4 wk) and there was no further follow-up. Pain intensity at palpation and at stretching, dorsiflexion range of motion, and heel raise test values showed significant improvements (P < .05) between pretreatment and posttreatment for both groups, however, no significant differences were observed between groups. Curve sprint tests did not show significant differences between pretreatment and posttreatment for either group or between groups. However, the percentage of changes always revealed better values in favor of the PNE group. Both groups showed good player satisfaction with the therapies. The application of the US-guided PNE combined with a specific exercise program may cause clinical benefits in the treatment of female soccer players with soleus injury.



#11 Modelling the relationships between EEG signals, movement kinematics and outcome in soccer kicking

Reference: Cogn Neurodyn. 2022 Dec;16(6):1303-1321. doi: 10.1007/s11571-022-09786-2. Epub 2022 Feb 25.

Authors: Luiz H Palucci Vieira, Christopher Carling, João Pedro da Silva, Felipe B Santinelli, Paula F Polastri, Paulo R P Santiago, Fabio A Barbieri

Summary: The contribution of cortical activity (e.g. EEG recordings) in various brain regions to motor control during goal-directed manipulative tasks using lower limbs remains unexplored. Therefore, the aim of the current study was to determine the magnitude of associations between EEG-derived brain activity and soccer kicking parameters. Twenty-four under-17 players performed an instep kicking task (18 m from the goal) aiming to hit 1 × 1 m targets allocated in the goalpost upper corners in the presence of a goalkeeper. Using a portable 64-channel EEG system, brain oscillations in delta, theta, alpha, beta and gamma frequency bands were determined at the frontal, motor, parietal and occipital regions separately for three phases of the kicks: preparatory, approach and immediately prior to ball contact. Movement kinematic measures included segmental linear and relative velocities, angular joint displacement and velocities. Mean radial error and ball velocity were assumed as outcome indicators. A significant influence of frontal theta power immediately prior to ball contact was observed in the variance of ball velocity (R 2 = 35%, P = 0.01) while the expression of occipital alpha component recorded during the preparatory phase contributed to the mean radial error (R 2 = 20%, P = 0.049). Ankle eversion angle at impact moment likely mediated the association between frontal theta power and subsequent ball velocity (β = 0.151, P = 0.06). The present analysis showed that the brain signalling at cortical level may be determinant in movement control, ball velocity and accuracy when performing kick attempts from the edge of penalty area. Trial registration number #RBR-8prx2m-Brazilian Registry of Clinical Trials ReBec.



#12 Low sleep quality and morningness-eveningness scale score may impair ball placement but not kicking velocity in youth academy soccer players

Reference: Sci Med Footb. 2022 Nov;6(4):528-538. doi: 10.1080/24733938.2021.2014550. Epub 2021 Dec 15.

Authors: Luiz H Palucci Vieira, Michele Lastella, João Pedro da Silva, Tiago Cesário, Felipe B Santinelli, Gabriel F Moretto, Paulo R P Santiago, Fabio A Barbieri

Summary: The current study examined the possible relationships between one-off single night sleep metrics and subsequent kicking performance in a youth soccer context. Twenty-eight under-17 academy players (15.9 ± 0.8 years-old) completed a kick testing protocol consisting in 20 attempts, 18 m from the goal and against a goalkeeper. Four digital video cameras (240 Hz) allowed to determine 3-D approach run, lower limb and ball velocities. Two additional cameras (60 Hz) were used to calculate 2-D mean radial error, bivariate variable error and accuracy. Over 24 h prior to testing, players were monitored by wrist actigraphy to determine their sleep indices. Self-reported sleep quality, sleepiness and chronotype scale scores (Horne and Östberg morningness-eveningness questionnaire) were also collected immediately before kicking experiment. Multiple linear regressions indicated that wake up time and chronotype contributed to 40% of mean radial error. Self-reported sleep quality influenced respectively on 19% and 24% of accuracy and bivariate variable error variances. Taken together self-reported sleep quality and wake up time explained 33% of accuracy (all p < 0.05). Indicators of kicking velocity were non-significantly correlated with sleep (r = -0.30-0.29; p > 0.05). One-off sleep measures showed some sensitivity to acutely detect inter-individual oscillations in kicking performance. Low perceived sleep quality, later wake up time and a chronotype toward evening preference seem either related to immediately subsequent worst ability of ball placement when kicking. Monitoring sleep-wake transition and perceived sleep quality may be important to help prevent acute performance declines in targeting the goal during kick attempts from the edge of penalty area.



#13 The impact of simulated soccer match-play on hip and hamstring strength in academy soccer players

Reference: Sci Med Footb. 2022 Nov;6(4):465-472. doi: 10.1080/24733938.2021.1973080. Epub 2021 Aug 31.

Authors: Jamie Salter, R Cresswell, D Forsdyke

Summary: Together, the burden of hamstring and hip and groin injuries in soccer is substantial and the risk of re-injury in these areas is high. Reduced muscle strength has been identified as an important modifiable intrinsic risk factor of injury. However, little is known regarding the within-match changes in hip and hamstring muscle strength in order to inform early detection and management strategies. Seventy-one male soccer players (age, 19.2 ± 0.9 yrs; height, 175.9 ± 5.8 cm; weight, 73 ±8.2 kg) from an international academy completed a fixed soccer-specific activity profile (SAFT90). Isometric hip and eccentric hamstring strength were measured after a standardised 5-min warm-up and repeated at half time and full time. Repeated-measures ANOVA were used to determine changes in muscle strength with magnitude-based decisions used to express probabilistic uncertainty. Findings indicate that i) there was likely to very likely substantial changes in isometric hip strength (-9.9-15.7%) and ii) no substantial changes in eccentric hamstring strength (-2.6-5.1%). By extrapolating these findings, it can be inferred that reduced isometric hip strength during match play may be one risk factor for injury, especially during periods of fixture congestion and practitioners should routinely assess muscle strength to inform training and match exposure based on player readiness. In doing so, it is likely that practitioners may enhance player availability and minimise injury incidence.



#14 Classification and determinants of passing difficulty in soccer: a multivariate approach

Reference: Sci Med Footb. 2022 Nov;6(4):483-493. doi: 10.1080/24733938.2021.1986227. Epub 2021 Oct 15.

Authors: Murilo Merlin, Allan Pinto, Alexandre Gomes de Almeida, Felipe A Moura, Ricardo Da Silva Torres, Sergio Augusto Cunha

Summary: Usually, the players' or teams' efficiency to perform passes is measured in terms of accuracy. The degree of difficulty of this action has been overlooked in the literature. The present study aimed to classify the degree of passing difficulty in soccer matches and to identify and to discuss the variables that most explain the passing difficulty using spatiotemporal data. The data used corresponds to 2,856 passes and 32 independent variables. The Fisher Discriminant Analysis presented 72.0% of the original grouped cases classified correctly. The passes analyzed were classified as low (56.5%), medium (22.6%), and high difficulty (20.9%), and we identified 16 variables that best explain the degree of passing difficulty related to the passing receiver, ball trajectory, pitch position and passing player. The merit and ability of the player to perform passes with high difficulty should be valued and can be used to rank the best players and teams.In addition, the highlighted variables should be looked carefully by coaches when analyzing profiles, strengths and weaknesses of players and teams, and talent identification context. The values found for each variable can be used as a reference for planning training, such as small side games, and in future research.



#15 The influence of short sprint performance, acceleration, and deceleration mechanical properties on change of direction ability in soccer players-A cross-sectional study

Reference: Front Physiol. 2022 Nov 2;13:1027811. doi: 10.3389/fphys.2022.1027811. eCollection 2022.

Authors: Qingshan Zhang, Alexandre Dellal, Karim Chamari, Pierre-Hugues Igonin, Cyril Martin, Christophe Hautier

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Summary: The study investigated the relationship between short sprint performance and mechanical parameters obtained during the acceleration and deceleration tasks with the change of direction (COD) performance in female and male soccer players. The acceleration and deceleration ability were compared in the "High/Fast" versus "Low/Slow" COD performance group based on a median split analysis in each sex group. One hundred three French soccer players were assessed for the sprinting Force-Velocity (F-V) profile (i.e., theoretical maximal force [F0], velocity [V0], power [Pmax]), 10 m performance, linear deceleration test (maximal braking force [HBFmax], braking power [BPmax], deceleration [Decmax]), and COD performance using 505-test. The 10 m performance was strongly associated with 505-test performance (ES = [0.64 to 0.71]), whereas the sprinting F-V profiles parameters were weakly to moderately correlated with 505- performance (ES = [-0.47 to -0.38]). The BPmax was also moderately associated with 505-test performance (ES: range = [-0.55 to -0.46]). In addition, the High/Fast female COD group presented higher F0, Pmax, HBFmax, and BPmax than the Low/Slow group, whereas the male groups presented very few mechanical differences. Multiple regression analysis shows that the COD performance of male players was determined by 10 m performance and maximum deceleration power. In contrast, no statistically significant model could be found to determine the change of direction performance in female players. In conclusion, the current finding indicated that the only variable strongly associated with COD performance was the linear 10 m sprint time. In the same way, the mechanical parameters obtained from acceleration and deceleration seemed to play a non-neglectable role in this population.



#16 The reality of organizational health in the Central Iraqi Football Federation from the point of view of those who manage the implementation of the annual curriculum

Reference: J Popul Ther Clin Pharmacol. 2022 Nov 19;29(4):e55-e68. doi: 10.47750/jptcp.2022.947. eCollection 2022.

Authors: Saba Qays Ghadhban

Summary: The aim of this research is to identify the strengths and weaknesses of organizational health in the Iraqi Central Handball Federation from the point of view of those who manage the implementation of the annual curriculum, and adopt a descriptive approach in the method of studying the case. This is based on a sample of administrators of the Iraqi Handball Federation curriculum [trainers, governors, members, president, the 138 members of the Central Federation's Administrative Authority, the President, members of the sub-federations of the sports market (2021/2022) selected deliberately by 100% and then divided into statistical analysis sample (30), reconnaissance sample (10), and application sample (98)]. The regulatory health questionnaire in its Italian version was prepared to suit the specificity of the research and the type of sample it was assigned in accordance with systematic sequential steps for its acceptance of the main measurement cad actor in this research. This was then applied to address the problem researched, and its data were processed by the system (SPSS) to make conclusions and applications that help regulatory health in support of the efforts of the Central Handball Federation to implement the annual curriculum from the point of view of those who manage its implementation, and help activate the role of sponsors to manage the implementation of the annual curriculum in the Central Handball Federation effectively, and was then applied to address the research problem. It has complementary factors that need to be available at a high level in the Central Handball Federation to help manage the implementation of the annual curriculum in full, and its specificity in managing the implementation of the annual curriculum in the Central Handball Federation requires comprehensiveness and the need for its elements to achieve a high level of it. It is necessary to support them in the formation of the Central Handball Federation to further activate the role of the worlds and determine their role and avoid feeling the loss of efforts, a careful and periodic review of the level of organizational health must be conducted before planning the annual curriculum in the Central Handball Federation, modifying the paths of weakness, supporting its strengths and taking into account its suitability in order to achieve the goals when implemented later.



#17 Monitoring the beautiful adapted game: a 3-year prospective surveillance study of injuries in elite English Para football

Reference: Sci Med Footb. 2022 Nov;6(4):415-420. doi: 10.1080/24733938.2021.1984556. Epub 2021 Oct 1.

Authors: Richard Weiler, Evert Verhagen, Aileen Taylor, Osman Hassan Ahmed

Summary: Para football is currently played in impairment-specific formats by thousands of people worldwide. To date, there have been no prospective longitudinal injury surveillance studies. This study aimed to implement a prospective injury surveillance study within elite English Para football and analyse the injury risk within the England Blind and Cerebral Palsy (CP) squads. Match and training injury data based on a 'time loss' definition were collected and analysed for each squad including incidence per 1,000 player hours, severity, injury location and associated event of injury. Injury incidence were lower in training than matches (CP 67.6/1000 player match hours (CI 33.8-135.2) and 5.7/1000 training hours (CI 3.8-8.7) and Blind 44.0/1000 player match hours (CI 26.1-74.3) and 5.5/1000 training hours (CI 3.5-8.6). Training injuries were more severe than match injuries across both squads (CP median 12 days lost in matches and 16 training and Blind median days 5 matches and 12 training). 73% Blind and 74% CP footballer injuries were to the lower limb and 17% head and neck equally across both Para football squads. 'Muscle and tendon injuries' (51%) represented the greatest proportion of injuries for CP footballers, and 'joint (non-bone)/ligament injuries' (43%) for Blind footballers. Collaboration and implementation of higher quality surveillance methodology and data collection in Para sport with greater athlete numbers are needed to inform injury prevention strategies.



#18 Perceiving, reporting and managing an injury - perspectives from national team football players, coaches, and health professionals

Reference: Sci Med Footb. 2022 Nov;6(4):421-433. doi: 10.1080/24733938.2021.1985164. Epub 2021 Oct 21.

Authors: Sandro Vella, Caroline Bolling, Evert Verhagen, Isabel Sarah Moore

Summary: Injury perceptions and related risk-mitigating interventions are context-dependent. Despite this, most injury surveillance systems are not context-specific as they do not integrate end-users perspectives. The purpose was to explore how Maltese national team football players, coaches, and health professionals perceive a football-related injury and how their context influences their perceptions and behaviours towards reporting and managing a football injury. 13 semi-structured interviews with Maltese female and male national team football players (n = 7), coaches (n = 3), and health professionals (n = 3) were conducted. Data were analysed using thematic analysis. Three themes were identified: (1) How do I perceive an injury? Consisted of various constructs of a sports injury, yet commonly defined based on performance limitations. (2) How do I deal with an injury? Encapsulated the process of managing the injury (3) What influences my perception, reporting and management of an injury? Comprised personal and contextual factors that influenced the perception and, consequently, the management of an injury. Performance limitations should be used as part of future injury definitions in injury surveillance systems. Human interaction should be involved in all the processes of an injury surveillance framework, emphasising its active role to guide the injury management process.



#19 Quantity and quality of sleep in young players of a professional football club

Reference: Sci Med Footb. 2022 Nov;6(4):539-544. doi: 10.1080/24733938.2021.1962541. Epub 2021 Aug 17.

Authors: Ana Merayo, Jose Miguel Gallego, Oscar Sans, Lluis Capdevila, Alex Iranzo, Dai Sugimoto, Gil Rodas

Summary: The aim was to investigate the quantity and quality of sleep hours in young athletes in a professional football club, to study if there is a significant relationship with mood state and subjective well-being, and to identify the relationship between sleep and quarterly academic performance. We also explored the relationship between sleep and quarterly academic performance. The study included 261 players of the various age group categories from football at Barcelona Football Club (average age:13.04 ± 3.16). Participants maintained a sleep diary and completed questionnaires on their mood state and the quantity and quality of their sleep. 70% of the athletes slept less hours than recommended by the American National Sleep Foundation. Athletes with worse quantity and quality of sleep showed negative effects on academic results. The results show that the majority of young players sleep less than recommended and show that those who sleep more hours obtain better academic results.



#20 Injuries are negatively associated with player progression in an elite football academy

Reference: Sci Med Footb. 2022 Nov;6(4):405-414. doi: 10.1080/24733938.2021.1943756. Epub 2021 Aug 17.

Authors: Jon Larruskain, Jose A Lekue, Imanol Martin-Garetxana, Irantzu Barrio, Alan McCall, Susana M Gil

Summary: The aim was to investigate the association of injuries with male football player continuity, progression and chances of reaching the First team in an elite academy. Injuries and exposure time were prospectively recorded, following the FIFA guidelines, over 6 seasons (2011-2017) in Under (U)12, U14, U16, U19, 2nd/3rd team and First team players from the same professional football club. U19 and 2nd/3rd team players progressing to the next level had a lower injury burden and higher match availability compared to players that did not progress. Injury burden was lower in players progressing from U12 to U14. All players progressing from the 2nd/3rd teams to the First team had a match availability higher than 84% and did not suffer an anterior cruciate ligament (ACL) rupture or an injury requiring over 200 (+200) days to return to play. In U19 and 2nd/3rd team players, injuries requiring +100 and +200 days to return to play, ACL ruptures and groin pain, but not hamstring and ankle ligament injuries, were associated with lower odds of continuing in the academy each season. Injuries were negatively associated with player progression, and injury prevention and return-to-play strategies should be a priority for football academies.







Weekly Training Load across a Standard Microcycle in a Sub-Elite Youth Football Academy: A Comparison between Starters and Non-Starters

The aim of this study was to compare the weekly training load on a standard microcycle in starters (START) and non-starters (NoSTART) of a sub-elite youth football academy.





Effects of an experimental short-time high-intensity warm-up on explosive muscle strength performance in soccer players: A pilot study

This study evaluated the effects of an a short time warm-up consisting of a small number of intermittent high-intensity sprints on explosive muscle strength performance in soccer players and to identify recovery times after performing the sprints. Reliability of a smartphone app for jumping performance was established.





Latest research in football - week 46 -2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Brain Endurance Training Improves Physical, Cognitive, and Multitasking Performance in Professional Football Players

Reference: Int J Sports Physiol Perform. 2022 Nov 11;1-9. doi: 10.1123/ijspp.2022-0144. Online ahead of print.

Authors: Walter Staiano, Michele Merlini, Marco Romagnoli, Ulrich Kirk, Christopher Ring, Samuele Marcora

Summary: Brain endurance training (BET)-the combination of physical training with mentally fatiguing tasks-could help athletes adapt and increase their performance during sporting competitions. Here we tested whether BET completed after standard physical training improved physical and mental performance more than physical training alone during a preseason football training camp. The study employed a pretest/training/posttest design, with 22 professional football players randomly assigned to BET or a control group. Both groups completed 40 physical training sessions over 4 weeks. At the end of a day of physical training, the BET group completed cognitive training, whereas the control group listened to neutral sounds. Players completed the 30-15 Intermittent Fitness Test, repeated sprint ability random test, soccer-specific reactive agility test, and Stroop and psychomotor vigilance tests pretraining and posttraining. Mixed analysis of variance was used to analyze the data. In the posttest (but not pretest) assessments, the BET group consistently outperformed the control group. Specifically, the BET group was faster (P = .02-.04) than the control group during the 30-15 Intermittent Fitness Test, the directional phase of the repeated sprint ability random test, and the soccer-specific reactive agility test. The BET group also made fewer errors (P = .02) during the soccer-specific reactive agility test than the control group. Finally, the BET group responded faster (P = .02) on the Stroop test and made fewer (P = .03) lapses on the psychomotor vigilance test than the control group. The inclusion of BET during the preseason seems more effective than standard physical training alone in improving the physical, cognitive, and multitasking performance of professional football players.



#2 Association of the CKM rs8111989 Polymorphism with Injury Epidemiology in Football Players

Reference: Int J Sports Med. 2022 Nov 11. doi: 10.1055/a-1945-8982. Online ahead of print.

Authors: David Varillas-Delgado, Esther Morencos, Jorge Gutierrez-Hellín, Millan Aguilar-Navarro, Antonio Maestro, Teresa Perucho, Juan Del Coso

Summary: The influence of the rs8111989 polymorphism in the muscle-specific creatine kinase gene (CKM) on injury incidence is unknown. The aim was to investigate CKM polymorphism on injury incidence in high-performance football players. A cohort of 109 high-performance players was genotyped by using saliva samples. Injury incidence was similar in players with the GG, GA, and AA genotypes and did not modify incidence during training or match exposure (p=0.583 and p=0.737 respectively). GG players had a higher frequency of slight-severity injuries (60.0 vs. 10.2 vs. 24.2%, p<0.001), while GA players had a higher frequency of severe injuries (16.7 vs. 30.8 vs. 10.0%, p=0.021). GA players also had a higher frequency of muscle tears (34.8 vs. 59.0 vs. 20.0%, p<0.001). Muscle contracture was a more frequent injury in players with the GG genotype (40.0%, p<0.001). G allele carriers had lower frequencies of gradual-onset injuries (4.1 vs. 16.7%, p=0.035) and recurrent injuries (6.1 vs. 16.7%, p=0.003) than AA players. A allele carriers had higher frequency of severe injuries (10.0 vs. 21.9%, p=0.044) than GG players. Genotypes in the CKM rs8111989 polymorphism did not affect injury incidence in high-performance football players. Players with the GA genotype were more prone to severe injuries and muscle tears when compared to GG and AA players.



#3 Science and the World Cup: how big data is transforming football

Reference: Nature. 2022 Nov;611(7936):444-446. doi: 10.1038/d41586-022-03698-1.

Authors: David Adam

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#4 Differences in Body Composition Analysis by DEXA, Skinfold and BIA Methods in Young Football Players

Reference: Children (Basel). 2022 Oct 28;9(11):1643. doi: 10.3390/children9111643.

Authors: José Francisco Tornero-Aguilera, Bella Esperanza Villegas-Mora, Vicente Javier Clemente-Suárez

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Summary: The most widely used method in professional sports for fat percentage assessment is the skinfold method. However, there is the chance of bias and human error. For this reason, other more precise methods are used, such as single-frequency bioelectrical impedance analysis (BIA) or dual energy X-ray absorptiometry (DEXA). However, there are limited data that demonstrate the methodological shortcomings or congruences in fat and fat-free mass estimates including gender differences and differences in athlete populations. Thus, the aim of the present study was to compare total body fat (%BF) estimated by six skinfold thickness measurement (SKF) and single-frequency bioelectrical impedance analysis (BIA) methods, using three different sets of equations, to that assessed by the dual energy X-ray absorptiometry (DEXA) method using a DEXA Hologic Serie Discovery QDR. For this aim, 76 males and 70 females belonging to the professional Spanish football federation were evaluated. We found significant differences between the three measures. BIA significantly underestimates the fat percentage, followed by skinfolds. With DEXA being the more objective or accurate method, an equation is established by means of linear regression analysis that allows the percentage of adipose tissue to be obtained either through anthropometry or electrical bioimpedance and adjusted to that which would be obtained by the DEXA system.



#5 Genetic Variations between Youth and Professional Development Phase English Academy Football Players

Reference: Genes (Basel). 2022 Nov 1;13(11):2001. doi: 10.3390/genes13112001.

Authors: Alexander B T McAuley, David C Hughes, Loukia G Tsaprouni, Ian Varley, Bruce Suraci, Joseph Baker, Adam J Herbert, Adam L Kelly

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Summary: The purpose of this study was to examine differences in the genotype frequency distribution of thirty-three single nucleotide variants (SNVs) between youth development phase (YDP) and professional development phase (PDP) academy football players. One hundred and sixty-six male football players from two Category 1 and Category 3 English academies were examined within their specific age phase: YDP (n = 92; aged 13.84 ± 1.63 years) and PDP (n = 74; aged 18.09 ± 1.51 years). Fisher's exact tests were used to compare individual genotype frequencies, whereas unweighted and weighted total genotype scores (TGS; TWGS) were computed to assess differences in polygenic profiles. In isolation, the IL6 (rs1800795) G allele was overrepresented in PDP players (90.5%) compared to YDP players (77.2%; p = 0.023), whereby PDP players had nearly three times the odds of possessing a G allele (OR = 2.83, 95% CI: 1.13-7.09). The TGS (p = 0.001) and TWGS (p &lt; 0.001) were significant, but poor, in distinguishing YDP and PDP players (AUC = 0.643-0.694), with PDP players exhibiting an overall more power-orientated polygenic profile. If validated in larger independent youth football cohorts, these findings may have important implications for future studies examining genetic associations in youth football.



#6 Effect of playing position and microcycle days on the acceleration speed profile of elite football players

Reference: Sci Rep. 2022 Nov 10;12(1):19266. doi: 10.1038/s41598-022-23790-w.

Authors: Antonio Alonso-Callejo, Jorge García-Unanue, Andrés Perez-Guerra, David Gomez, Javier Sánchez-Sánchez, Leonor Gallardo, Jose María Oliva-Lozano, Jose Luis Felipe

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Summary: The aim of this study was to analyse the differences in the A-S profile of elite football players induced by playing position and the microcycle day. Players belonged to a second division club in the Spanish La Liga competition. They were classified into five playing positions: central defenders (CD), full backs (FB), midfielders (MF), wide midfielders (WMF) and forwards (FW). Microcycle days were categorised according to the days until matchday (MD, MD-1, MD-2, MD-3, MD-4 and MD-5). Data was collected along six microcycles, including one match per microcycle. The variables analysed were: maximal theoretical acceleration (A0), maximal theoretical speed (S0), maximal acceleration (ACCmax), maximal speed (Smax) and A-S slope (ASslope). Significant differences were found within positions and microcycle day for all variables (p < 0.05). Match day (MD) showed greater values than the training sessions in A0, ACCmax and Smax (p < 0.05). The highest values for variables associated with acceleration capabilities were found in CD on MD, whereas speed variables were higher in WMF. MD-2 showed the lowest values in all variables except for ASslope. Maximal acceleration and sprint abilities are therefore affected by playing position. Wide positions showed the highest speed capacity, and CD presented a likely acceleration profile. Higher values for all variables concerning the microcycle day, were achieved on MD, and were not reproduced during training with the consequent injury risk and performance decrease it takes.



#7 The Effects of a Weighted Football Intervention on Ball Velocity of a Standard Football Place-Kick among Elite Gaelic Football Goalkeepers: A Single-Subject Designed Study

Reference: Sports (Basel). 2022 Oct 28;10(11):166. doi: 10.3390/sports10110166.

Authors: Sam Jermyn, Cian O'Neill, Seán Lacey, Edward K Coughlan

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Summary: Weighted football place-kicking acutely enhances the ball velocity (BV) of subsequent standard football place-kicks. However, there is a dearth of research examining the long-term effects of such interventions, with less evidence in existence among elite athlete cohorts. Therefore, the purpose of this study was to investigate the individual effects of a 4 week, eight-session weighted Gaelic football intervention on BV of standard Gaelic football place-kicks among six elite male Gaelic football goalkeepers. This research design was based on a pre-, mid-, post-, and retention-test design. A linear mixed model analysis was employed, with time and participants as fixed effects, and the number of place-kicks per testing session as a random effect. Post hoc tests revealed significant changes in BV for five of the six participants (p &lt; 0.05), with three participants experiencing significant BV increases from pre-test to post-test (p &lt; 0.05), while no significant differences were found between post-test and retention-test. The remaining three participants experienced no significant BV differences from pre-test to post-test and retention-test. These findings suggest that a weighted football place-kicking intervention can be a time-efficient means of maintaining and enhancing BV and, thus, kick distance, among elite goalkeepers during pre-season and in-season phases.



#8 The prevalence and determinants of anterior cruciate ligament rupture among athletes practicing football in Jeddah Avenues 2020

Reference: J Family Med Prim Care. 2022 Aug;11(8):4528-4535. doi: 10.4103/jfmpc.jfmpc_61_22. Epub 2022 Aug 30.

Authors: Fahad Salem Alqarni, Khalid Omair Alshehri, Turki Muteb Alotaibi, Assaf Nahar Alsulami, Abdulaziz Omair Alshehri, Khaled Saeed Aseri

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Summary: Anterior cruciate ligament (ACL) tear is a common sport injury and one of the most serious sport injuries affecting non-professionals and professional athletes. It is most commonly torn during sports that involve sudden stops and changes in direction such as football. The aim was too measure the prevalence and determinants of anterior cruciate ligament rupture as well as assess knowledge about it among young adult athletes practicing football. An analytical cross-sectional study based on a questionnaire was carried out during the period from December 2019 to March 2020 among a sample of Saudi athletes recruited from natural grass, artificial turf, and dirt football fields in the Jeddah region. A structured questionnaire composed of four parts was used to collect data: socio-demographic variables, questions to assess awareness and knowledge of ACL, questions to assess the prevalence and determinants of ACL, and description of cases and the Arabic version of the Lysholm Knee Score (LKS) to assess the impact of ACL injury on patients' daily life. The study included 320 participants. Their age ranged between 15 and 40 years with an arithmetic mean of 27.9 and a standard deviation of ±6.8 years. The majority of them were males (97.8%). The prevalence of ACL injury was 14.7% among the participants; it was significantly higher among overweight and obese subjects (P = 0.042) as well as those who reported more than 10 training weekly hours (P = 0.034). Most of the playgrounds at the time of injury were either artificial turf (44.7%) or dirt football fields (34%). Overall, the level of adequate knowledge about ACL was observed among most of the participants (70.3%). The only factor significantly associated with the level of participants' knowledge about ACL was the level of physical activity, P = 0.011. The total of LKS ranged between 21 and 100 with a median (inter-quartile range) of 82.5 (57-91). The prevalence rate of ACL injury among athletes in Jeddah, Saudi Arabia, is within the world wide range. Their awareness and knowledge of ACL are encouraging, although some risk factors were not well known. The quality of life of injured athletes was high, irrespective of demographic as well as physical factors and the history of surgical repair.



#9 Immediate Effects of Spinal Manipulative Therapy on the Performance of Elite Brazilian Soccer Players: A Pilot Randomized Controlled Trial With an Internally Validated Sham Treatment

Reference: J Chiropr Med. 2022 Dec;21(4):270-279. doi: 10.1016/j.jcm.2022.02.021. Epub 2022 Jul 15.

Authors: Marcelo B Botelho, Marcio A Barbosa, Celso S Junior, Jerusa P R Lara, Alexandre Moreira, Abrahão F Baptista

Summary: The purpose of this study was to assess the feasibility of the procedures' routine, the recruiting rate, the presence of any significant detrimental impact on the players' training routine, and the sham efficacy in achieving blinding. A parallel randomized controlled clinical trial was performed with 20 elite soccer players who were randomly assigned to 1 of 2 groups: spinal manipulative therapy (SMT) and sham SMT. All players were from the same team, were injury free, and were naive to SMT. Measured outcome tests (30-m sprint run with a 10-m split and change of direction [COD] test) were performed at the same time by all participants immediately before and after interventions. Photocell devices were used for data acquisition. Twenty participants were analyzed (10 in each group). There were no changes to the sprint (10 m and 30 m) and COD test results immediately after either of the interventions. All participants in both groups (SMT and sham SMT) answered "yes" to a question after the intervention asking if they were treated by SMT. No adverse effects or training routine impairment were reported. This pilot study protocol showed it was an appropriate design for a confirmatory clinical trial. The study had minimal effect on the team training routine, and the recruitment rate was excellent. The proposed sham SMT strategy was successful in blinding the players. In this sample, SMT did not have any immediate effect on the performance of these elite soccer players, as measured by 10- and 30-m sprint times and COD sprint times.



#10 Match activity profile of professional female soccer players during a season

Reference: J Exerc Rehabil. 2022 Oct 26;18(5):324-329. doi: 10.12965/jer.2244354.177. eCollection 2022 Oct.

Authors: Jun-Hyuk Choi, Chang-Hwa Joo

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Summary: It is necessary to understand movement characteristics of elite female soccer players during a match to develop effective training program. The purpose of this study is to analyze the physical demands of Korean female professional soccer players during a competitive season. Twenty-four female professional players (age: 27.8±3.9 years; height: 165.7± 5.1 cm) from a team, belonging to the women's professional soccer league in South Korea participated in the study. The players participated in 11 home matches and 10 away matches from April 26 to November 9 of the 2011 season. Body weight and body mass index decreased during the first half-season compared to the preseason (P<0.05), and the decreased values were maintained until the second half-season. Total distance covered by the players was more than 9.5 km per match. No difference was found in the total distance, movement distance by exercise intensities, number of sprints and accelerations, and maximum speed between the first half- and second half-seasons. Midfielders covered the most distance during a match compared to other positions (P<0.05). Wing forward covered the most distance of high-intensity exercise. Maximum speed during the match was higher among wing forward and forward than in other positions (P<0.05). There were no significant differences between home and away matches in all variables (P>0.05). In conclusion, in order to improve the performance of female soccer players and prevent injuries, a training program should be constructed that considers the characteristics of each player and playing position rather than uniform training in a team.



#11 Men Are from Quartile One, Women Are from? Relative Age Effect in European Soccer and the Influence of Age, Success, and Playing Status

Reference: Children (Basel). 2022 Nov 14;9(11):1747. doi: 10.3390/children9111747.

Authors: Matthew Andrew, Laura Finnegan, Naomi Datson, James H Dugdale

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Summary: The relative age effect (RAE) is characterised by an overrepresentation of athletes born earlier in the selection year. Whilst an RAE is consistently evident in male soccer, examinations in female players remain limited. The aim of the present study was to examine the influence of sex, as well as age, success, and playing status in European soccer players. The sample consisted of a total of 6546 soccer players from 55 soccer nations that competed in recent European Championship qualification campaigns. Results indicated an evident RAE in male [p = 0.017] but not female [p = 0.765] players. Male players were over-represented by players born in the first quartile for the U17 [p &lt; 0.001] and U19 [p = 0.001] levels, however, this over-representation did not transfer to senior levels. No RAE was observed at any level for female players. Inside each age group, a slight selection bias towards those born in the first quartile for successful squads was observed but did not significantly differentiate between qualification status for either male or female players. Results from this study highlight the disparity in RAE prevalence between male and female players and raise further questions regarding the value of selecting relatively older players to metrics of success, transition, and selection for senior international soccer.



#12 Recreational Soccer Training Effects on Pediatric Populations Physical Fitness and Health: A Systematic Review

Reference: Children (Basel). 2022 Nov 18;9(11):1776. doi: 10.3390/children9111776.

Authors: Filipe Manuel Clemente, Jason Moran, Rodrigo Ramirez-Campillo, Rafael Oliveira, João Brito, Ana Filipa Silva, Georgian Badicu, Gibson Praça, Hugo Sarmento

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Summary: This systematic review analyzed the effects of recreational soccer programs on physical fitness and health-related outcomes in youth populations. Studies were sought in the following databases: (i) PubMed, (ii) Scopus, (iii) SPORTDiscus, and (iv) Web of Science. The eligibility criteria included (1) population: youth (&lt;18 years old) populations with no restrictions on sex or health condition; (2) intervention: exposure to a recreational soccer training program of at least four weeks duration; (3) comparator: a passive or active control group not exposed to a recreational soccer training program; (4) outcomes: physical fitness (e.g., aerobic, strength, speed, and change-of-direction) or health-related measures (e.g., body composition, blood pressure, heart rate variability, and biomarkers); (5) study design: a randomized parallel group design. The search was conducted on 6 September 2022 with no restrictions as to date or language. The risk of bias was assessed using the PEDro scale for randomized controlled studies. From a pool of 37,235 potentially relevant articles, 17 were eligible for inclusion in this review. Most of the experimental studies revealed the beneficial effects of recreational soccer for improving aerobic fitness and its benefits in terms of blood pressure and heart-rate markers. However, body composition was not significantly improved by recreational soccer. The main results revealed that recreational soccer training programs that are implemented twice a week could improve the generality of physical fitness parameters and beneficially impact cardiovascular health and biomarkers. Thus, recreational soccer meets the conditions for being included in the physical education curriculum as a good strategy for the benefit of the general health of children and young people.



#13 Physical Fitness Variations between Those Playing More and Those Playing Less Time in the Matches: A Case-Control Study in Youth Soccer Players

Reference: Children (Basel). 2022 Nov 21;9(11):1786. doi: 10.3390/children9111786.

Authors: Ana Filipa Silva, Filipe Manuel Clemente, César Leão, Rafael Oliveira, Georgian Badicu, Hadi Nobari, Luca Poli, Roberto Carvutto, Gianpiero Greco, Francesco Fischetti, Stefania Cataldi

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Summary: The purpose of this study was (i) to compare two groups (players with more vs. less match play time) regarding body composition, vertical and horizontal jumping performance, and aerobic capacity; and (ii) to test the relationships between physical fitness and play time. This study followed a case-control design in which the outcome was playtime, and the causal attribute was physical fitness. Sixty-six youth male soccer players from under-16 (n = 21), under-17 (n = 19), under-18 (n = 12), and under-19 (n = 14) age groups were monitored for match play time during five months of observation. Inclusion criteria consisted of (1) no absence of more than a week due to injury or other conditions during the five months of observation and (2) physical assessments having been done simultaneously with those of the other players (at the beginning of the season). The exclusion criteria were (1) not participating in one week or more of training sessions, and (2) not participating in the physical fitness assessments. At the beginning of the season, players were assessed for anthropometry (height, body mass, skinfolds), countermovement jump, triple hop bilateral and unilateral jump, and aerobic capacity using the Yo-Yo Intermittent Recovery Test, level 2 (YYIRT). The group that played more time had significantly greater YYIRT results (+28.2%; p = 0.009; Cohen's d = 0.664). No other significant differences were found between those who played more and fewer minutes. Moderate and significant linear positive correlations were found between YYIRT and play time in the under-19 group (r = 0.423; p = 0.031) and overall (r = 0.401; p &lt; 0.001). In the case of the under-17 group, moderate and significant linear positive correlations were found between TSA and play time (r = 0.473; p = 0.041). This suggests that aerobic and anaerobic capacity is related to play time while jumping performance and fat mass seem not to play an essential role in play time.



#14 Analysis of the Anaerobic Power Output, Dynamic Stability, Lower Limb Strength, and Power of Elite Soccer Players Based on Their Field Position

Reference: Healthcare (Basel). 2022 Nov 10;10(11):2256. doi: 10.3390/healthcare10112256.

Authors: Ali AlTaweel, Shibili Nuhmani, Mohammad Ahsan, Wafa Hashem Al Muslem, Turki Abualait, Qassim Ibrahim Muaidi

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Summary: Soccer players require a high degree of aerobic and anaerobic fitness to perform well throughout the game as per their position in the field. This study aimed to investigate the differences in anaerobic power output, dynamic stability, lower limb strength, and power among elite soccer players based on their field position. A cross-sectional population of 96 elite soccer players with average age 23.10 ± 4.35 years, weight 69.99 ± 9.71 kg, height 174.84 ± 6.64 cm, and body mass index 22.84 ± 2.39 kg/m2 from various soccer clubs in Saudi Arabia was tested for their anaerobic power output, dynamic stability, lower limb strength, and power performance. All the participants have more than 4 years of experience in competitive soccer events. Tests included a measure of single-leg vertical jump, star excursion balance test, and single-leg triple hop test for distance. The players were divided into four groups (goalkeepers, defenders, midfielders, and attackers) based on their self-reported position on the field. One-way ANOVA was used to determine the differences between all variables according to the players' position. In addition, partial eta-squared (ηp2) was used to report effect sizes. The results revealed significant differences between positions in the anaerobic power output (p = 0.012, ηp2 = 0.312), dynamic stability {Anterior (p = 0.004, ηp2 = 0.235), Anteromedial (p = 0.007, ηp2 = 0.622), Anterolateral (p = 0.011, ηp2 = 0.114)}, and lower limb strength, and power (p = 0.008, ηp2 = 0.421). At the same time, goalkeepers' performance was significantly superior to midfielders (p = 0.006) in the anaerobic power output. In addition, lower limb strength and power was significantly higher (p = 0.004) for goalkeepers than for midfielders, with a similar trend in dynamic stability (p = 0.007). These results exhibited differences in anaerobic power output, dynamic stability, lower limb strength, and power performance based on the players' positions. The investigation may assist the practitioner in designing training programs for the players according to their position for performance improvement.



#15 Muscle Asymmetries in the Lower Limbs of Male Soccer Players: Preliminary Findings on the Association between Countermovement Jump and Tensiomyography

Reference: Sports (Basel). 2022 Nov 14;10(11):177. doi: 10.3390/sports10110177.

Authors: Alex Buoite Stella, Annalisa Galimi, Miriam Martini, Luca Di Lenarda, Luigi Murena, Manuela Deodato

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Summary: Strength and power asymmetries have been observed in different sports, including soccer. Such asymmetries, as well as the bilateral deficit (BLD), can be assessed during different tasks, static or dynamic, and with different methods and devices, in order to detect the possible different aspects, as well as the association with physical performance and injuries. The aim of this study was to investigate the association between muscle asymmetries and BLD during a countermovement jump (CMJ), and tensiomyography (TMG) parameters and asymmetries, in the lower limbs of male soccer players. A total of 23 male soccer players (18 ± 4 years) were recruited. Bilateral and unilateral CMJs were performed, and peak power (W) and height (cm) were obtained. TMG was performed on different muscles of the lower limbs, and lateral and functional symmetries were obtained. Playing position and history of injuries were collected. CMJ inter-limb symmetry was found to significantly correlate with biceps femoris (r = 0.574, p = 0.004) and soleus (r = 0.437, p = 0.037) lateral symmetry. Players in central roles presented significantly worse functional symmetry scores of the knee than defense players (-17.5%, 95% CI -31.2--3.9; p = 0.10). Participants reporting a history of injury at the ankle were characterized by significantly lower functional symmetry in both the dominant (43%, 39.5-48.0 vs. 74.5%, 46.5-89.3, p = 0.019) and non-dominant (45%, 42.5-46.0 vs. 81.0%, 45.8-90.3, p = 0.024) ankle. Findings from this preliminary study suggest an association between lower-limb muscle asymmetries during a dynamic task, such as jumping, and muscle contractile properties evaluated with TMG; moreover, functional asymmetries may be present after ankle injuries. Future studies in larger samples should evaluate the presence of such asymmetries as predictors or characteristics of different muscular and joint injuries.



#16 Effects of Age and Playing Tactics on the Individual Tactical Behavior in U10 and U12 Elite Spanish Soccer Players

Reference: Sports (Basel). 2022 Nov 21;10(11):185. doi: 10.3390/sports10110185.

Authors: Joaquín González-Rodenas, Gonzalo Pedrera, Víctor Dorado, Rodrigo Aranda-Malavés, Andrés Tudela-Desantes, Pedro De Matías-Cid

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Summary: The aim of this paper was to explore the effects of age and playing tactics on the individual tactical behavior and performance in young soccer players. A total of 1247 individual possessions during 16 knockout matches from LaLiga Promises U12 tournament (n = 621) and LaLiga U10 Iscar Cup (n = 626) were analyzed by observational methodology. Multilevel and multivariate logistic regression models were created to explain the interdependent effects of age category and playing tactics on the individual tactical behavior and performance. Youth players performed most of their actions against defensive pressure (72.5%), during offensive support (91.3%) and receiving the ball facing forward (62.6%). The most frequent action was to receive and pass the ball (69.6%) and the level of offensive success was 56.9%. The multilevel mixed models revealed that U10 players presented higher odds of running with the ball vs. passing the ball (OR = 1.823; 95% CI: 1.333-2.493; p &lt; 0.001) and lower odds of achieving offensive success (OR = 0.698; 95% CI: 0.525-0.928; p &lt; 0.05) than U12 players. Regarding playing tactics, technical-tactical dimensions such as the players' body shape when receiving the ball, offensive support, defensive pressure, collective type of attack and type of technical action presented a significant and combined effect on the offensive success regardless of age category, playing position and match status. This study found tactical differences between U10 and U12 age categories and revealed important interactive effects of multiple tactical dimensions on the individual offensive behavior and performance in youth soccer players.



#17 Testing the effects of 4-week training programs based on extreme and medium-sided soccer games: a study focusing on change-of-direction, vertical jump height and locomotor profile

Reference: BMC Sports Sci Med Rehabil. 2022 Nov 24;14(1):199. doi: 10.1186/s13102-022-00592-1.

Authors: Piotr Makar, Gibson Praça, Adam Kawczyński, Zeki Akyildiz, Mehmet Yıldız, Rodrigo Aquino, Filipe Manuel Clemente

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Summary: This study tested the effects of two training programs (one program based on extreme sided-games of 1v1 vs. one program based on the medium-sided game of 5v5) on the physical fitness adaptations of youth soccer players. In specific, it was analyzed the effects of the training programs on the 5-0-5 change-of-direction time (5-0-5 time), countermovement jump (CMJ), and final velocity in the 30-15 Intermittent Fitness test (VIFT). This study followed a randomized parallel study design. Twenty male regional-level soccer players (age: 17.0 ± 0.3 years old) were randomly assigned to two groups: (1) the 1v1 format; and (2) the 5v5 format. The training intervention lasted four weeks. The week before (baseline) and the week after the intervention, the participants were assessed in the 5-0-5 change-of-direction test (measured using timing gates), CMJ (measured by photoelectric cells), and 30-15 Intermittent Fitness test. The training intervention consisted of 8 sessions (2 sessions per week). The 1v1 group performed four repetitions of 30 s in each session, while the 5v5 group performed four repetitions of 4 min. The 5-0-5 time changed - 4.82% (p = 0.004; d = 1.115) for the 1v1 group and - 4.26% (p = 0.004; d = 0.859) for the 5v5 group. CMJ changes occurred both in the 1v1 and 5v5 group and amounted to 1.7% (p = 0.003; d = 0.509) and 1.2% (p = 0.263; d = 0.155) respectively. VIFT changed 2.6% (p = 0.718; d = 0.178) for the 1v1 group and 3.0% (p = 0.593; d = 0.274) for the 5v5 group. The 1v1 group reported significantly lower post-intervention 5-0-5 time than the 5v5 group (- 4.3%; p = 0.048; d = 0.954), although no significant differences in CMJ (3.2%; p = 0.147; d = 0.678) and VIFT (2.5%; p = 0.697; d = 0.177) were revealed. The extreme-sided games meaningfully beneficiated the vertical jump height and change-of-direction performance of youth soccer players. The extreme-sided games seem more beneficial than medium-sided games for improving these physical abilities while showing that four weeks were enough to impact the players significantly.



#18 Daytime fluctuations of endurance performance in young soccer players: a randomized cross-over trial

Reference: BMC Res Notes. 2022 Nov 24;15(1):351. doi: 10.1186/s13104-022-06247-1.

Authors: Janis Fiedler, Stefan Altmann, Hamdi Chtourou, Florian A Engel, Rainer Neumann, Alexander Woll

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Summary: Fluctuations of physical performance and biological responses during a repetitive daily 24-h cycle are known as circadian rhythms. These circadian rhythms can influence the optimal time of day for endurance performance and related parameters which can be crucial in a variety of sports disciplines. The current study aimed to evaluate the daytime variations in endurance running performance in a 3.000-m field run and endurance running performance, blood lactate levels, and heart rate in an incremental treadmill test in adolescent soccer players. In this study, 15 adolescent male soccer players (age: 18.0 ± 0.6 years) performed a 3.000-m run and an incremental treadmill test at 7:00-8:00 a.m. and 7:00-8:00 p.m. in a randomized cross-over manner. No significant variations after a Bonferroni correction were evident in endurance running performance, perceived exertion, blood lactate levels, and heart rates between the morning and the evening. Here, the largest effect size was observed for maximal blood lactate concentration (9.15 ± 2.18 mmol/l vs. 10.64 ± 2.30 mmol/l, p = .110, ES = 0.67). Therefore, endurance running performance and physiological responses during a field-based 3.000-m run and a laboratory-based test in young male soccer players indicated no evidence for daytime variations.







Effect of Small-Sided Games with and without the Offside Rule on Young Soccer Players: Reliability of Physiological Demands

This study aimed to compare the physiological demand between three vs. three small-sided games (SSGs) with (3vs.3WITH) and without (3vs.3WITHOUT) the offside rule, as well as the within and between-session reliability.





Season Match Loads of Under-23 Soccer Team: Differences between Different Starting Statuses throughout the Season

This study aimed to quantify the external match loads (EMLs) of a Portuguese U23 soccer team, competing at the highest national level for the age group, comparing players with different starting status throughout a competitive season and specific blocks.





Latest research in football - week 45 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 A classification of specific movement skills and patterns during sprinting in English Premier League soccer

Reference: PLoS One. 2022 Nov 11;17(11):e0277326. doi: 10.1371/journal.pone.0277326. eCollection 2022.

Authors: Paul Caldbeck, Thomas Dos'Santos

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Summary: The aim of this study was to quantify and contextualize sprinting actions (≥ 7.0 m/s) of English Premier League (EPL) soccer match-play with respect to the movement skills and patterns employed. Video footage (3.2.6, Premier League DVMS, ChyronHego) and raw video-based locomotor coordinates of 901 sprint efforts from 10 matches of an EPL soccer team (2017-2018), were evaluated using the Football Sprint Movement Classification System pertaining to transition, initiation, and actualisation of sprint movement skills and patterns. The results from a one-way ANOVA or independent t-test revealed that, generally, most sprinting actions begun from a linear initiation position compared to lateral or rear (63%, d = 5.0-5.3, p &lt; 0.01), without a change of direction (COD) (48%, d = 4.9-5.6, p &lt; 0.01) compared to lateral, front-back, back-front, and from forward travelling (linear and diagonal) transition movements (68%, d = 2.1-5.7, p &lt; 0.01) compared to lateral or rear. Additionally, most sprints were initiated with a rolling acceleration (66%, d = 3.2, p &lt; 0.01) compared to explosive acceleration, often performed with a degree of curvature (86%, d = 7.2, p &lt; 0.01) compared to linear, with torso rotation (62%, d = 2.7, p &lt; 0.01) compared to no rotation, and typically end with an action such as duelling with an opponent or involvement with the ball (49%). Additionally, the sprint movement characteristics proportions slightly differed across playing positions. Overall, this study confirms that sprints during EPL soccer matches are initiated from and performed with a variety of different movement skills and patterns in relation to different sport-specific outcomes. This data can be used to assist in the development of more effective physical preparation programmes, inform position-specific contextualized sprinting drills to achieve better specificity and potential transfer of training, while also informing speed testing protocols.



#2 Dehydration, Wellness, and Training Demands of Professional Soccer Players during Preseason

Reference: Biomed Res Int. 2022 Nov 7;2022:8054449. doi: 10.1155/2022/8054449. eCollection 2022.

Authors: César Leão, Francisco Tomás González-Fernández, Halil İbrahim Ceylan, Filipe Manuel Clemente, Hadi Nobari, Miguel Camões, José Maria Cancela Carral

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Summary: Our study is aimed at analyzing the relationships between water loss and a professional soccer team's internal and external training load throughout the first three months of a season, covering all the preseason and the first two months of the competitive season. This study followed an observational analytic design. Twenty-seven athletes (age: 25.5 ± 4.1 years, height: 180.7 ± 8.2 cm, and body mass: 78.4 ± 8.7 kg) were included in the study, conducted over the first three months of the season. Players were weighed at the beginning and end of all training sessions to estimate fluid losses. They were asked to complete a wellness questionnaire and indicate the color of the first urine of the day upon their arrival at the practice session. Additionally, all sessions were monitored for locomotor demands. We found a positive correlation between urine color and sprint distance (r = 0.46, p = 0.01) and a positive correlation between dehydration and rating of perceived exertion (r = 0.44, p = 0.015), whereas a negative correlation between dehydration and number of acceleration (r = -0.39, p = 0.034).

Conclusions: Dehydration increased perceived physical exertion. Regularly monitoring training load and changes in body mass, as well as raising awareness about hydration, can contribute to cognitive and physical performance.



#3 Associations among Maturity, Accumulated Workload, Physiological, and Body Composition Factors in Youth Soccer Players: A Comparison between Playing Positions

Reference: Biology (Basel). 2022 Nov 2;11(11):1605. doi: 10.3390/biology11111605.

Authors: Hadi Nobari, Özgür Eken, Pablo Prieto-González, João Paulo Brito, Rafael Oliveira

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Summary: The purposes of this study were: (i) to analyze the correlation between accumulated workload (AW)-based on season periods-with maturity, linear sprints, maximum oxygen uptake (VO2max), maximum heart rate, and body composition; and (ii) to compare the playing positions based on the mentioned parameters. Twenty-one elite soccer players under the age of 14 participated in the study. They were divided into five groups based on playing positions. The in-season weekly AW was recorded for 26 weeks into two separated periods of 13 weeks (AW-1 and AW-2). Similarly, the following parameters were assessed: body mass, standing and sitting height, body mass index, body fat percentage, maturity offset, age at peak height velocity (PHV), sprinting ability (10 m and 30 m), and VO2max. The main significant differences between playing positions were found for weight, height, sitting height, and sprinting at 10 m and 30 m. No correlation was observed between AW (based on periods) and maturity or between VO2max and AW-2. AW-1 denoted a large positive correlation with AW-2. AW-1 had a moderate negative correlation with VO2max, whereas PHV and maturity presented a strong negative correlation. Young soccer players' maturity statuses and fitness levels do not imply differences between AW-1 and AW-2. However, the higher the AW in the first half of the season, the higher the AW in the second half. The absence of significant differences between player positions could be associated with the similar training regardless of the playing position. Moreover, soccer positively influences performance in short sprints (10 m), midfielders being the fastest.



#4 Maturation Selection Biases and Relative Age Effect in Italian Soccer Players of Different Levels

Reference: Biology (Basel). 2022 Oct 24;11(11):1559. doi: 10.3390/biology11111559.

Authors: Stefania Toselli, Mario Mauro, Alessia Grigoletto, Stefania Cataldi, Luca Benedetti, Gianni Nanni, Riccardo Di Miceli, Paolo Aiello, Davide Gallamini, Francesco Fischetti, Gianpiero Greco

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Summary: Soccer is a sport practiced all over the world, in which players are expected to show specific physical and technical skills. Soccer academies look for young talented individuals to develop promising players. Although several parameters could affect the players' performance, the relative age effect (RAE) and the maturity status appeared debated. Therefore, this study compared the differences in RAE and biological maturity among the players of two Italian soccer teams of different levels and to understand their interaction effects with the competition level on youth players' physical characteristics and abilities. One hundred and sixty-two young soccer players from the U12 to U15 age categories of the elite (n = 98) and non-elite (n = 64) teams were recruited. The prevalence of maturity status and RAE was observed. Many anthropometric parameters, BIA vectors, and motor tests (CMJ, Sprint, RSA) were carried out. The maturity status had a greater effect on several anthropometric characteristics and on 15 m sprint, while it affected the CMJ only in U12 (F = 6.187, p ≤ 0.01). Differently, the RAE seemed to priorly affect the U13 and U15 categories in body composition, whereas its effect appeared on the 15-m sprint (F(3, 45) = 4.147, p ≤ 0.01) and the RSA (F(3, 45) = 3.179, p ≤ 0.05) in the U14 category. In addition, early matured players or those who were born in the first six months presented cellular characteristics similar to adult elite players. Soccer professionals should be encouraged to monitor the maturity status to better interpret changes in the physical performance of young soccer players to guide adequate training plans.



#5 Variations in Accumulated-Training Load Parameters and Locomotor Demand with Consideration of Puberty in Elite Young Soccer Players

Reference: Biology (Basel). 2022 Oct 30;11(11):1594. doi: 10.3390/biology11111594.

Authors: Hadi Nobari, Hamed Kia Shemshaki, Okan Kamiş, Rafael Oliveira, Pablo Prieto González, Elena Mainer-Pardos

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Summary: The study's purposes were to examine the associations of training load parameters with locomotor demand and puberty status in elite young soccer players and to predict the percentage of changes in their performance ability with adjustments to the training load parameters, using multivariate regression analysis, while considering PHV and maturity offset. Seventeen male players (15-16 years old) participated in this study. Anthropometrics, body composition, maximal oxygen consumption (VO2max), and puberty status (for calculating PHV) and maturity offset were assessed. The results demonstrated substantial differences between the PHV, VO2max, and load parameters (acute and chronic workload (CWL)) over a soccer season. A substantial relationship existed between the workload parameters (VO2max, CWL, and training monotony (TM)) and maturity offset. All of the variables, except for training strain, demonstrated significant variances in relation to the differences between the first and second halves (p &lt; 0.05). Aerobic performance can be estimated using the CWL, TM, and maturity offset values (R2 = 0.46). On the contrary, aerobic power performance can be explained using the acute:chronic workload, TM, and PHV values (R2 = 0.40). In conclusion, the biological maturity state of young soccer players has a substantial impact on their functional potential. Variations in accumulated load contribute significantly to aerobic resistance, whereas weight and height contribute significantly to sprint and vertical-jump performance, respectively.



#6 A Pilot Study on the Prediction of Non-Contact Muscle Injuries Based on ACTN3 R577X and ACE I/D Polymorphisms in Professional Soccer Athletes

Reference: Genes (Basel). 2022 Nov 2;13(11):2009. doi: 10.3390/genes13112009.

Authors: Kathleen Y de Almeida, Tiago Cetolin, Andrea Rita Marrero, Aderbal Silva Aguiar Junior, Pedro Mohr, Naoki Kikuchi

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Summary: Muscle injuries are among the main reasons for medical leavings of soccer athletes, being a major concern within professional teams and their prevention associated with sport success. Several factors are associated with a greater predisposition to injury, and genetic background is increasingly being investigated. The aim of this study was to analyze whether ACTN3 R577X and ACE I/D polymorphisms are predictors of the incidence and severity of muscle injury in professional soccer athletes from Brazil, individually and in association. Eighty-three professional athletes from the first and second divisions of the Brazilian Championship were evaluated regarding the polymorphisms through blood samples. Nighty-nine muscle injuries were identified during the seasons of 2018, 2019 and 2020 and categorized according to severity. ACTN3 XX individuals had a higher frequency of severe injuries compared to the RX and RR genotypes (p = 0.001), and in the dominant model (compared to RX+RR), with p &lt; 0.001. The trend p-value test showed an increased number of injuries/season following the order XX &gt; RX &gt; RR (p = 0.045). Those with the ACE II genotype had almost 2 fold the number of injuries per season compared to those with the ID+DD genotypes (p = 0.03). Logistic regression showed that the polymorphisms are predictors of the development of severe injury (ACTN3 R577X model with p = 0.004, R2: 0.259; ACE I/D model with p = 0.045, R2: 0.163), where ACTN3 XX individuals were more likely to suffer from severe injury (OR: 5.141, 95% CI: 1.472-17.961, p = 0.010). The combination of the ACTN3 577X allele and the ACE II genotype showed an increased number of injuries per season, enhanced by 100% (1.682 injuries/season versus 0.868 injuries/season, p = 0.016). Our findings suggest that both polymorphisms ACTN3 R577X and ACE I/D (and their interaction) are associated with the susceptibility and severity of non-contact muscle injury in soccer players.



#7 Comparison of the Effects of Different Forms of Nutrition Education on Adolescent Male Soccer Players

Reference: Int J Environ Res Public Health. 2022 Oct 24;19(21):13803. doi: 10.3390/ijerph192113803.

Authors: Ziyu Gao, Sicheng Wang, Lianlian Peng, Lei Sun, Peng Qiu, Bingyi Bai, Qingqing Zhang, Junyu Wu, Yu Zha, Fenglin Zhu, Qirong Wang

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Summary: The purpose of this study was to compare the educational effects on nutrition knowledge of two teaching methods targeting adolescent male soccer players through learning online from WeChat account articles (WeChat group) or taking classroom courses (classroom group). The study investigates whether such teaching methods can improve self-efficacy and nutrition knowledge for athletes. A total of 41 U15 (age 15) youth male soccer players, 21 in the classroom group and 20 in the WeChat group, participated in the experiment by receiving the same nutrition education separately for 12 weeks. An athlete nutrition KAP questionnaire and self-efficacy questionnaire were conducted before the intervention, immediately after the intervention, and 6 weeks and 12 weeks after the intervention. As a result, the nutritional knowledge score and the total score of the athlete nutrition KAP questionnaire in the classroom group increased significantly and were notably higher than those in the WeChat group. Self-efficacy scores improved significantly in both groups. In conclusion, the study showed that the level of nutritional knowledge of U15 male soccer players was mediocre, and both forms of nutrition education can significantly improve the level of nutritional knowledge and self-efficacy of the players. In comparison, the educational effect of classroom teaching is significantly greater and more consistent than that of learning from WeChat public articles.



#8 Comparison of the Physical, Physiological, and Psychological Responses of the High-Intensity Interval (HIIT) and Small-Sided Games (SSG) Training Programs in Young Elite Soccer Players

Reference: Int J Environ Res Public Health. 2022 Oct 24;19(21):13807. doi: 10.3390/ijerph192113807.

Authors: Zied Ouertatani, Okba Selmi, Santo Marsigliante, Bilel Aydi, Nadhir Hammami, Antonella Muscella

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Summary: We investigated the effects of high-intensity interval (HIIT) and small-sided games (SSG) training programs on physiological and psychological responses in young soccer players. Twenty-four male soccer players (age 16.7 ± 0.9 years) were divided into two groups (HIIT and SSG) and completed a 6-week training programs consisting of two training sessions a week. HIIT consisted of intermittent runs lasting 15 s at the 110% maximum aerobic speed followed by a passive recovery lasting 15 s; SSG was instead structured in a 4 versus 4 players games on a playing field of 25 × 35 m. The muscular power of the lower body was assessed before and after each training session using the 5-jump test to leg length, and two incremental field tests (VAMEVAL test and modified agility t-test). Our results show that HIIT and SSG have similar beneficial effects on the variables connected to the soccer-specific performance and the endurance with little influence on neuromuscular performances. Psychological responses were assessed using the "physical activity enjoyment scale", the Hooper index and the POMS variables. Results showed that SSG offers greater perceived enjoyment than what can be achieved with HIIT. In conclusion, SSG can be considered an effective, more motivating, and fun soccer-specific training that brings about physiological responses and neuromuscular adjustments in young soccer players.



#9 Physical Impact of a Typical Training Session with Different Volumes on the Day Preceding a Match in Academy Soccer Players

Reference: Int J Environ Res Public Health. 2022 Oct 24;19(21):13828. doi: 10.3390/ijerph192113828.

Authors: Tom Douchet, Christos Paizis, Nicolas Babault

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Summary: French academies almost all implement reactivity drills and small-sided games (SSG) the day preceding a match (MD-1). The present study aimed to determine the physical impact of different training durations on MD-1 on the subsequent matchday performance (MD). Eleven elite U19 academy soccer players conducted three typical training sessions lasting 45 min (TS45), 60 min (TS60) and 75 min (TS75) on MD-1. During TS60, warm-up, reactivity and SSG were 10, 15 and 24 min, respectively, plus coaches' feedback or water breaks. Durations of all training components decreased by 25% for TS45 and increased by 25% for TS75. Tests were conducted on MD-4 (CONTROL) and MD before the match (TEST). Tests consisted of a counter movement jump (CMJ), 20 m sprint, Illinois agility test (IAT) and Hooper questionnaire. CONTROL values were similar over the three experimental conditions. TEST on MD revealed greater CMJ for TS45 (42.7 ± 5.1 cm) compared to TS60 (40.5 ± 5.5 cm, p = 0.032) and TS75 (40.9 ± 5.7 cm, p = 0.037). 20 m time was lower for TS45 (3.07 ± 0.10 s, p &lt; 0.001) and TS60 (3.13 ± 0.10 s, p = 0.017) compared to TS75 (3.20 ± 0.10 s). IAT time was lower on TS45 (14.82 ± 0.49 s) compared to TS60 (15.43 ± 0.29 s, p &lt; 0.001) and TS75 (15.24 ± 0.33 s, p = 0.006). Furthermore, the Hooper index was lower at TEST for TS45 (7.64 ± 1.50) compared to TS60 (11.00 ± 3.49, p = 0.016) and TS75 (9.73 ± 2.41, p = 0.016), indicating a better readiness level. We concluded that, as training session duration increases, performance decreases on MD. A 45 min training session including reactivity and SSG exercises is therefore recommended on MD-1.



#10 The Effects of Small-Sided Games and Behavioral Interventions on the Physical and Motivational Outcomes of Youth Soccer Players

Reference: Int J Environ Res Public Health. 2022 Oct 29;19(21):14141. doi: 10.3390/ijerph192114141.

Authors: Rareș-Mihai Pop, Vlad Teodor Grosu, Emilia Florina Grosu, Alexandru Zadic, Liliana Mâță, Tatiana Dobrescu

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Summary: The objective of this study was to test the effects of two types of intervention, one based on small-sided games (SSGs), and the other one that had, in addition, a behavioral component consisting of goal setting, public posting, and positive reinforcement. The participants were 16 male soccer players aged 12-14 years old who participated in a couple of training sessions per week between August and November 2021. We used Playr Catapult GPS devices to assess the effect of the intervention on the total distance covered and total sprint distance in the task of playing SSGs. We used Yo-Yo Intermittent Recovery Test Level 1 to test the effect of the intervention on players' aerobic capacity and the Task and Ego Orientation in Sport Questionnaire to investigate levels of motivational climate. Multiple two-way mixed ANOVAs were conducted and the results indicated that our intervention had a positive effect on the total distance and total sprint distance covered during SSGs. For aerobic capacity, even if the results were not significant, they indicate a high effect size. The effect of the intervention on task-oriented motivational climate and ego-oriented motivational climate was not significant. Discussions focus on the application of the intervention in team training settings.



#11 Despite Good Correlations, There Is No Exact Coincidence between Isometric and Dynamic Strength Measurements in Elite Youth Soccer Players

Reference: Sports (Basel). 2022 Nov 10;10(11):175. doi: 10.3390/sports10110175.

Authors: Carl-M Wagner, Konstantin Warneke, Christoph Bächer, Christian Liefke, Philipp Paintner, Larissa Kuhn, Torsten Brauner, Klaus Wirth, Michael Keiner

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Summary: Speed strength performances are substantially dependent on maximum strength. Due to their importance, various methods have been utilized to measure maximum strength (e.g., isometric or dynamic) with discussed differences regarding transferability to sport-specific movements dependent upon the testing procedure. The aim of this study was to analyze whether maximum isometric force (MIF) during isometric back squats correlates with maximum strength measurements of the one repetition maximum (1RM) in the squat, with countermovement jump (CMJ) performance, and with drop jump (DJ) performances in elite youth soccer players (n = 16, 18.4 ± 1.5 [range: 17-23] years old). Additionally, concordance correlation coefficients (CCC, [ρc]) between isometric and dynamic measurements were calculated to verify whether one measurement can actually reproduce the results of the other. To improve comprehension, differences between isometric and dynamic testing values were illustrated by providing differences between both testing conditions. For this, the mean absolute error (MAE) and the mean absolute percentage error (MAPE) were calculated. To reach equality in scale, the 1RM measures were multiplicated by 9.81 to obtain a value of N. The 1RM demonstrated correlations of τ = |0.38| to |0.52| with SJ and CMJ performances, while MIF demonstrated correlations of τ = |0.21| to |0.32|. However, the correlations of both 1RM and MIF with the DJ reactive strength index (RSI = jump height /contact time) from different falling heights were of no statistical significance. The data showed significant correlations between both the absolute (τ = |0.54|) and the relative (τ = |0.40|) performances of 1RM and MIF, which were confirmed by CCC of ρc= |0.56| to |0.66|, respectively. Furthermore, the MAE and MAPE showed values of 2080.87 N and 67.4%, respectively. The data in this study show that, despite good correlations, there is no exact coincidence between isometric and dynamic strength measurements. Accordingly, both measurements may only represent an estimation of maximal strength capacity and cannot be substituted for each other. Therefore, maximal strength should be tested by using high similarity in the contraction condition, as it is used in the training process to counteract underestimation in strength because of unfamiliarity with the testing condition.



#12 Monitoring Internal Training Intensity Correlated with Neuromuscular and Well-Being Status in Croatian Professional Soccer Players during Five Weeks of the Pre-Season Training Phase

Reference: Sports (Basel). 2022 Nov 2;10(11):172. doi: 10.3390/sports10110172.

Authors: Josip Maleš, Ibrahim Ouergui, Danijela Kuna, Frane Žuvela, Andrea De Giorgio, Goran Kuvačić

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Summary: This study aimed to investigate the changes in internal training intensity, well-being, and countermovement jump (CMJ) performance and to determine their relationship across five weeks of the pre-season training phase in professional soccer players. A total of 22 professional male soccer players (age = 21.7 ± 4 years, body height = 185.9 ± 6.3 cm, body weight = 79 ± 6.3 kg, BMI = 22.8 ± 1.4 kg·m-2; VO2max = 52.9 ± 3.2) from the Croatian Second League voluntary participated in this study. The players spent 2230 ± 117 min in 32 technical/tactical and strength/conditioning training sessions, mostly at the low intensity zone (61%), and played 8 friendly matches at a high intensity (&gt;90%). A one-way repeated measure of analysis ANOVA revealed a significant difference between weeks in CMJ performance (F(1,22) = 11.8, p &lt; 0.001), with CMJ height in weeks 4 and 5 being likely to very likely higher than that noted in week 1. Moreover, significant differences between weeks were found in all internal training intensity measures (average [F(1,22) = 74.8, p &lt; 0.001] and accumulated weekly internal training intensity [F(1,22) = 55.4, p &lt; 0.001], training monotony [F(1,22) = 23.9, p &lt; 0.001], and training strain [F(1,22) = 34.5, p &lt; 0.001]). Likewise, differences were observed for wellness status categories (fatigue [F(1,22) = 4.3, p = 0.003], sleep [F(1,22) = 7.1, p &lt; 0.001], DOMS [F(1,22) = 5.7, p &lt; 0.001], stress [F(1,22) = 15.6, p &lt; 0.001]), mood [F(1,22) = 12.7, p &lt; 0.001], and overall well-being status score (F(1,22) = 13.2, p &lt; 0.001). Correlation analysis showed large negative correlations between average weekly internal training intensity and fatigue (r = -0.63, p = 0.002), DOMS (r = -0.61, p = 0.003), and WBI (r = -0.53, p = 0.011). Additionally, fatigue was significantly associated (large negative correlation) with accumulated weekly internal training intensity (r = -0.51, p = 0.014) and training strain (r = -0.61, p = 0.003). Small, but non-significant, correlations were found between CMJ performance and wellness status measures. These findings highlight the utility and simplicity of monitoring tools to improve athletes' performance.



#13 Reliability and Validity of a Novel Reactive Agility Test with Soccer Goalkeeper-Specific Movements

Reference: Sports (Basel). 2022 Oct 31;10(11):169. doi: 10.3390/sports10110169.

Authors: Yosuke Abe, Hisataka Ambe, Tomoyasu Okuda, Masao Nakayama, Noriteru Morita

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Summary: The purpose of this study was to develop a reactive agility test with soccer goalkeeper (GK)-specific movements (G-RAT) and to examine the reliability and validity of college-aged GKs. We designed a five-branch star-shaped course with diving and ball-catching movements under reactive conditions. In the setup, a start-goal line was set on the top of a branch and 3.5 m away from the center of the star-shaped setting. Content validity was assessed by six experts, and the item-content validity index (I-CVI) was calculated. Thirty-three male GKs performed the test trial twice. One test trial of G-RAT consists of three shuttles from the start-goal line to diving and ball-catching. For the reactive condition, GKs were instructed on which ball directions should dive when their body trunk reached 1.5 m away from the start-goal line. GKs were classified into regular (R) or non-regular (NR) groups. The intraclass correlation coefficient (ICC) and the receiver operating characteristic (ROC) curve analyses were used to assess the reliability and predictive power as convergent validity. The I-CVI was 0.83, which was greater than the acceptable level of 0.78. The ICC value was 0.94 (p &lt; 0.01; 95% confidence interval (95%CI), 0.88-0.97). The GKs completed the test 14.3 ± 0.7 and15.3 ± 1.0 sec in the R and NR group (p &lt; 0.01; Cohen's d = 0.89), respectively. The area under the curves of G-RAT was 0.80 (95%CI, 0.64-0.96). These results show that a GK-specific agility test under reactive conditions would have sufficient reliability and both content and convergent validity in college-aged GKs.



#14 The Influence of Different Training Load Magnitudes on Sleep Pattern, Perceived Recovery, and Stress Tolerance in Young Soccer Players

Reference: J Strength Cond Res. 2022 Oct 20. doi: 10.1519/JSC.0000000000004235. Online ahead of print.

Authors: Ayrton Bruno de Morais Ferreira, Bruno Laerte Lopes Ribeiro, Elias Dos Santos Batista, Matheus Peixoto Dantas, Arnaldo Luis Mortatti

Summary: The aim of this study was to analyze the influence of 3 weeks on sleep parameters, perceived recovery, and stress tolerance in young soccer players using different training load magnitudes. A total of 13 young male soccer athletes (15.9 ± 0.5 years; 68.7 ± 6.1 kg; 170 ± 7 cm) who performed 3 typical training weeks with different workloads were analyzed. The external training load (ETL) was verified by the PlayerLoad method, and the internal training load (ITL) was determined using the session rating of perceived exertion method. Sleep was monitored using a wrist-actigraphy monitor. Sleep variables, including total time in bed (TTB), total sleep time (TST), sleep latency (SL), wake after sleep onset (WASO), and sleep efficiency (SE), were evaluated across all nights of sleep. The recovery status was assessed with the perceived recovery status (PRS) scale, and the stress tolerance was monitored using the "daily analysis of life demands of athletes" questionnaire. There was an increase in sleep time during the week with the highest training load (week 2) (TTB: +35 minutes, TST: +46 minutes, SL: -5 minutes, SE: +3%). There was no difference in the PRS or in the stress tolerance during the evaluation weeks. A very large within-individual correlation was observed between ITL and ETL (r = 0.78) and moderate within-individual correlation between ETL and TST (r = 0.34), between ITL and TST (r = 0.45), and between ITL and SE (r = 0.359). These results showed that there was an increase in TST during a microcycle with intensified loads, without impairing bedtime and resulting in maintenance of the perceived recovery or stress tolerance values.



#15 Comparison between predicted and measured resting energy expenditures in Korean male collegiate soccer players

Reference: Phys Act Nutr. 2022 Sep;26(3):25-31. doi: 10.20463/pan.2022.0015. Epub 2022 Sep 30.

Authors: Sihyung Lee, Kuniko Moto, Taewoong Oh, Motoko Taguchi

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Summary: This study aimed to evaluate the differences between predicted resting energy expenditure (REE), using fat-free mass (FFM)-based prediction equations, and measured REE in Korean male collegiate soccer players. Fifteen male collegiate soccer players (18-21 years) participated in this study. The REE measurements were conducted using the Douglas bag method. Body composition was measured by dual-energy X-ray absorptiometry (DXA). The differences between the measured REE and predicted REE, using the five FFM-based REE equations, were analyzed using the t-test, calculation of errors, regression analysis, and the Bland-Altman method. The Cunningham (1980) and ten Haaf and Weijs (2014) equations showed significantly overestimated REE (1,808 ± 99 kcal/d, p <0.01; 1,838 ± 103 kcal/d, p <0.01; respectively), but the Owen (1988), Taguchi (2011), and Kim (2015) equations' estimations were not significantly different from the measured REE (1,589 ± 106 kcal/d, 1,640 ± 124 kcal/d, and 1,622 ± 68 kcal/d, respectively). The Taguchi equation gave the best prediction of REE with the lowest constant error (-6 ± 125) and effect size (-0.05), and a non-significant proportional bias (p = 0.95). The Taguchi equation is recommended for predicting REE in Korean collegiate soccer players. The selection process of a REE-prediction equation must take into consideration the target population's characteristics. Future studies are recommended to evaluate the validity of the different FFM-based REE-prediction equations in various Korean athletes.



#16 Acute fuelling and recovery practices of academy soccer players: implications for growth, maturation, and physical performance

Reference: Sci Med Footb. 2022 Nov 9. doi: 10.1080/24733938.2022.2146178. Online ahead of print.

Authors: Reuben G Stables, Marcus P Hannon, Nessan B Costello, Sam J McHaffie, Jazz S Sodhi, Graeme L Close, James P Morton

Summary: Considering that academy soccer players frequently train in the evening (i.e. 17:00-20:00 h), there is often limited time to nutritionally prepare and recover due to schooling, travel and sleep schedules. Accordingly, we assessed the timing and quantity of dietary intake of academy soccer players in the pre-training and post-training period. Over a 3-day in-season training period, male adolescent players (n=48; n=8 from under (U) 12, 13, 14, 15/16, 18 and 23 players) from an English Premier League academy self-reported their dietary intake and physical activity levels (via the remote food photography method and activity diary, respectively) in the four hours before and after training. External training load was also quantified via GPS. Timing of pre-training energy intake ranged from 40 ± 28 mins (U15/U16 players) to 114 ± 71 mins (U18) before training and mean carbohydrate (CHO) intake ranged from 0.8±0.4 (U23) to 1.5±0.9 (U12). Timing of post-training energy intake ranged from 39 ± 27 mins (U14) to 70 ± 84 mins (U23) and mean CHO intake ranged from 1.6±0.8 (U12) to 0.9±0.5 (U14). In contrast to sub-optimal CHO intakes, all age groups consumed sufficient protein intake in the post-training period (i.e. > 0.3 We conclude academy soccer players habitually practice sub-optimal acute fuelling and recovery strategies, the consequence of which could impair growth, maturation and physical performance. Player and stakeholder education and behaviour change interventions should therefore target specific behaviours that lead to increased CHO intake before, during and after training.



#17 Complexity emerges in measures of the marking dynamics in football games

Reference: Phys Rev E. 2022 Oct;106(4-1):044308. doi: 10.1103/PhysRevE.106.044308.

Authors: A Chacoma, O V Billoni, M N Kuperman

Summary: In this article, we study the dynamics of marking in football matches. To do this, we survey and analyze a database containing the trajectories of players from both teams on the field of play during three professional games. We describe the dynamics through the construction of temporal bipartite networks of proximity. Based on the introduced concept of proximity, the nodes are the players, and the links are defined between opponents that are close enough to each other at a given moment. By studying the evolution of the heterogeneity parameter of the networks during the game, we characterize a scaling law for the average shape of the fluctuations, unveiling the emergence of complexity in the system. Moreover, we propose a simple model to simulate the players' motion in the field from where we obtained the evolution of a synthetic proximity network. We show that the model captures with a remarkable agreement the complexity of the empirical case, hence it proves to be helpful to elucidate the underlying mechanisms responsible for the observed phenomena.



#18 Chinese football violence: An extended theory of planned behavior model to predict fans' violent behavioral intentions

Reference: Front Psychol. 2022 Oct 31;13:977497. doi: 10.3389/fpsyg.2022.977497. eCollection 2022.

Authors: Yuge Tian, Chao Ma, Zhenguo Shi

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Summary: This study introduced deindividuation (DI) variables and constructed a mechanism model of football fans' violent behavioral intentions (FVBI) in China based on theory of planned behavior (TPB). Specifically, taking Chinese football fans as the research subjects, we used a structural equation model (SEM) to explore the specific effects of subjective norms (SNs), perceived behavioral control, DI, and attitude (AT) on violent behavior intentions. Our results showed that SNs (β = -0.132, P < 0.01) had a significant negative predictive effect on FVBI, while perceived behavioral control (β = 0.297, P < 0.01), DI (β = 0.239, P < 0.01), and AT (β = 0.416, P < 0.01) had a significant positive predictive effect. However, we found that AT was the most important factor that predicted the FVBI and played a mediating role between SNs and FVBI, between perceived behavior control (PBC) and FVBI, and between DI and FVBI as well.



#19 Performance Adaptations to Intensified Training in Top-Level Football

Reference: Sports Med. 2022 Nov 16;1-18. doi: 10.1007/s40279-022-01791-z. Online ahead of print.

Authors: Morten Hostrup, Jens Bangsbo

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Summary: Because physical demands are surging in football (soccer, USA), clubs are more and more seeking players who have a high capacity to perform repeated intense exercise. High-intensity interval training (HIIT), comprising exercise performed at intensities near or exceeding the capacity of aerobic energy systems, effectively enhances the physical conditioning of players. But given that HIIT imposes high loads, it increases the risk of overload-associated match performance decline and injury. This makes some coaches inclined to conduct HIIT in the weeks leading up to the season and during the season. Therefore, the challenge is how to optimize and dose HIIT during these phases, as they can be decisive. Studies have highlighted the utility of conducting periods of intensified training to overcome the risk of overload while at the same time enhancing performance. During intensified training periods of typically a few weeks, intensity is increased by enlarging the amount of HIIT, for example, aerobic high-intensity training or speed endurance training, while volume at low-to-moderate intensity is significantly reduced. The outcome depends on training composition and prescription-most notably, intensity and duration of bouts and recovery. When work intervals are prescribed for a few minutes at intensities > 90% heart rate max (i.e., aerobic high-intensity training), then beneficial adaptations pertaining to aerobic power and capacity are apparent. But when work intervals are conducted at much higher intensities, as all-out efforts or sprinting of typically 10- to 40-s duration with longer recovery periods (i.e., speed endurance training), beneficial adaptations pertaining to anaerobic energy systems, ion handling, and fatigue resilience are commonly observed. In this review, we discuss the utility of conducting intensified training periods to enhance performance in elite football players during the late preparation phase and competitive season.






Genetic profiles to identify talents in elite endurance athletes and professional football players

The genetic profile that is needed to identify talents has been studied extensively in recent years. The objective of this investigation was to approach, the study of genetic variants in several polygenic profiles and their role in elite endurance and professional football by comparing the allelic and genotypic frequencies to the non-athlete.





What are the significant turning demands of match play of an English Premier League soccer team?

This study aimed to compare the significant turning demands of English Premier League soccer match play relative to playing position using LiDAR technology.





Latest research in football - week 44 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Day type and start time may influence sleep in adolescent professional football players

Reference: Int J Sports Med. 2022 Nov 8. doi: 10.1055/a-1974-5441. Online ahead of print.

Authors: Luke Edinborough, Stewart Bruce-Low, Jessica Hill, Jonny Woodhouse, Mark Jarvis, Charles Pedlar

Summary: This study assessed if scheduling (start time and day type) and workload variables influenced sleep markers (activity monitor) in professional academy footballers (n=11; 17.3±0.7yrs) over a 10-week in-season period. Separate linear mixed regressions were used to describe the effect of start time on the previous nights sleep, and the effect of day type (matchday, matchday+1) and workload on subsequent sleep. Workload variables were modelled by day (day), 7-day (acute), and 28-day (chronic) periods. Sleep duration following matchday+1 (400mins; 95%CI:368-432) was significantly reduced compared to all other day types(p<0.001). Sleep onset time following matchday (00:35; CI:00:04-01:12) and wake time on matchday+1 (09:00; CI:08:37-09:23) were also significantly later compared to all other day types (p<0.001). Sleep duration (19.1mins; CI:9.4-28.79), wake time (18mins; CI:9.3-26.6), and time in bed (16.8mins; CI:2.0-31.5) were significantly increased per hour delay in start time. When no activity was scheduled sleep duration (37mins; CI:18.1-55.9), sleep onset (42.1mins; CI:28.8-56.2), and wake times (86mins; CI:72-100) were significantly extended, relative to a 09:00 start time. Day, acute, and chronic workloads were associated with sleep onset and wake times only. Scheduled start times were associated with changes in sleep duration, therefore, delaying start times may increase sleep in this population.



#2 Do sports-related concussions induce subsequent injuries in elite male football players?

Reference: Int J Sports Med. 2022 Nov 8. doi: 10.1055/a-1974-3965. Online ahead of print.

Authors: Florian Beaudouin, Tobias Tröß, Abed Hadji, Ida Bo Steendahl, Tim Meyer, Karen Aus der Fünten

Summary: To assess the players' risk of a subsequent injury after sustaining concussive injuries and their return-to-competition in German professional men's football. A prospective injury database in the 1st Bundesliga was created encompassing 7 seasons (2014/15-2020/21). Cox proportional hazard model analyzed whether a concussive injury increased the risk of a subsequent injury in the first year after the index injury. 6,651 injuries were reported (n=182 concussive injuries). The incidence rate was 0.15 (95% CI 0.13-0.17) per 1000 football hours. A concussive injury was associated with only a slightly numerical higher risk of 7% (HR=1.07, 95% CI 0.78-1.47) in the subsequent year after the injury compared to a randomly selected non-concussive injury, but the effect was not significant. The risk was higher after 6-12 months post-SRC reaching 70% (HR=1.70, 95% CI 1.15-2.52). For 0-3 months (HR=0.76, 95% CI 0.48-1.20) and 3-6 months (HR=0.97, 95% CI 0.62-1.50) the injury risk was lower. The present data do not confirm previously published investigations about an increased injury risk after SRC. Contrasting effects of lower hazard ratios were found early after SRC, followed by an increase after 6-12 months. Further research should look into compliance rates with regards to return-to-competition protocols.



#3 Prevalence of sport specialisation and association with injury history in youth football

Reference: Phys Ther Sport. 2022 Oct 29;58:160-166. doi: 10.1016/j.ptsp.2022.10.013. Online ahead of print.

Authors: Anja Zoellner, Chris Whatman, Kelly Sheerin, Paul Read

Summary: The aims of this study were to determine the prevalence of sport specialisation in youth football, and to investigate the associations of sport specialisation and volume of sport participation with injury history. New Zealand youth football teams were used for analysis. Therer were 414 youth football players aged 10-15 years. The level of specialisation, average weekly sport participation and free-play volume were recorded. 12-month injury history was captured and grouped by injury type. Associations between level of specialisation and demographic variables were analysed using chi square tests. Logistic regression was used to investigate associations between injury history, level of specialisation, and volume of participation. Participants were classified as high (43%), moderate (38%), or low (19%) specialised (n = 399 complete). High specialisation was more likely in boys, older participants, and those from large schools. Highly specialised participants were more likely to report a history of gradual onset injury than those who were low specialised (n = 340 with complete injury data). Odds of reporting a gradual onset injury also increased with greater weekly and annual sport participation volume. There is a high prevalence of sport specialisation in youth football, and it is associated with increased incidence of gradual onset injury.



#4 Selected Immunoendocrine Measures for Monitoring Responses to Training and Match Load in Professional Association Football: A Review of the Evidence

Reference: Int J Sports Physiol Perform. 2022 Nov 7;1-10. doi: 10.1123/ijspp.2022-0226. Online ahead of print.

Authors: Matthew Springham, Robert U Newton, Anthony J Strudwick, Mark Waldron

Summary: Biomarkers relating to player "stress balance," immunological (ie, immunoglobulin-A), and hormonal (ie, testosterone and cortisol [T:C]) status are now commonly used in football. This article is our critical review of the scientific literature relating to the response of these measures to player load and their relationships with player health. The commonly reported relationship between immunoglobulin-A and training or match load highlights its sensitivity to changes in psychophysiological stress and the increased risk of compromised mucosal immunity. This is supported by its close relationship with symptoms of upper respiratory tract infection and its association with perceived fatigue in football players. Testosterone and cortisol concentrations and the testosterone-cortisol ratio are sensitive to changes in player load, but the direction of their response is often inconsistent and is likely influenced by player training status and non-sport-related stressors. Some evidence indicates that sustained periods of high training volume can increase resting testosterone and that sustained periods of low and high training intensity can increase resting cortisol, compromising the testosterone-cortisol ratio. These findings are noteworthy, as recent findings indicate interrelationships between testosterone, cortisol, and testosterone:cortisol and perceived measures of fatigue, sleep quality, and muscle soreness in football players. Variability in individual responses suggests the need for a multivariate and individualized approach to player monitoring. Overall, we consider that there is sufficient evidence to support the use of salivary immunoglobulin-A, testosterone, cortisol, and testosterone:cortisol measures as part of a multivariate, individualized player monitoring system in professional football.



#5 Physical demands in Spanish male and female elite football referees during the competition: a prospective observational study

Reference: Sci Med Footb. 2022 Nov 7. doi: 10.1080/24733938.2022.2145015. Online ahead of print.

Authors: Maria Luisa Martin-Sanchez, José M Oliva-Lozano, Jorge Garcia-Unanue, Jose Luis Felipe, Víctor Moreno-Pérez, Leonor Gallardo, Javier Sánchez-Sánchez

Summary: The aim of this study was to analyze the physical demands of elite male and female field referees in match play and compare the physical demands between male and female football referees in the competition. Match data were collected from 36 elite football referees (19 males and 17 females) during a total of 409 football matches. Electronic performance and tracking systems based on global positioning systems (GPS) were used in this research. Male referees experienced significantly greater physical demands (p<0.05) in men league than female referees in women league for total distance, explosive distance, high-intensity breaking distance, total of sprints, sprinting distance, high-speed running distance, high-speed running actions, maximal speed, total of accelerations and decelerations, maximal acceleration and deceleration, acceleration/deceleration. Therefore, strength and conditioning coaches should consider these gender differences in match demands to maximize the fitness-fatigue response of the referees since this may lead to a better performance during the decision making process in the competition.



#6 Injury characteristics in Norwegian male professional football: A comparison between a regular season and a season in the pandemic

Reference: Front Sports Act Living. 2022 Oct 21;4:915581. doi: 10.3389/fspor.2022.915581. eCollection 2022.

Authors: Torstein Dalen-Lorentsen, Thor Einar Andersen, Christian Thorbjørnsen, Michael Brown, David Tovi, Anders Braastad, Tom Gerald Lindinger, Christian Williams, Eirik Moen, Benjamin Clarsen, John Bjørneboe

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Summary: The Coronavirus Disease-19 (COVID-19) pandemic forced the Norwegian male premier league football season to reschedule, reducing the fixture calendar substantially. Previous research has shown that a congested match schedule can affect injury rates in professional football. Therefore, we aimed to investigate whether the Norwegian premier league teams suffered more injuries in the more match congested 2020 season than in the regular 2019-season. We invited all teams having participated in both seasons to export their injury data. Only teams that used the same medical staff to register injuries in both seasons were included, and to maximize data comparability between seasons, we applied a time-loss injury definition only. Seven of 13 teams agreed to participate and exported their injury data. Both seasons had 30 game weeks, but the 2020 season was 57 days shorter than the 2019 season. The match injury incidence did not differ significantly [incidence rate ratio 0.76 (0.48-1.20; p = 0.24) in the 2020 season compared to the 2019 season. Furthermore, we found no differences in the number of injuries, days lost to injury, matches missed to injury, or injury severity. We could not detect any differences between the two seasons, suggesting the congested match calendar combined with the safety measures in the 2020 season can be a safe alternative in future seasons.



#7 Neuromuscular control of the lower extremities can be better enhanced by applying ankle taping and kinesiological taping rather than elastic bandaging: a randomized control study in amateur soccer players

Reference: J Phys Ther Sci. 2022 Nov;34(11):741-744. doi: 10.1589/jpts.34.741. Epub 2022 Nov 1.

Authors: Panagiotis Dendrinos, Athina Fassoi, Maria Tsekoura, Pavlos Angelopoulos, Konstantinos Mylonas, Dimitris Mandalidis, Georgios Krekoukias, Elias Tsepis, Konstantinos Fousekis

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Summary: This study evaluated the effects of ankle elastic bandaging, taping, and kinesiology taping on the neuromuscular control of the lower extremities before and after their application and after exercise in soccer athletes. Fifty-five amateur soccer players were randomly divided into four research sub-groups either receiving bandaging (n=15), taping (n=15), and kinesiology taping (n=15) on their ankle or serving as controls (n=10). The dynamic stability of the non-dominant limb was assessed through the star excursion balance test (SEBT) in three research conditions: a) before sports taping application, b) after the application, and c) after a 15 min laboratory simulation of soccer activities. Taping and kinesiology taping improved the dynamic stabilization of the lower limb more statistically significantly than bandaging. The addition of exercise significantly improved the SEBT results in the taping and kinesiology taping more than the bandaging and control groups. Exercise activates the proprioceptive mechanisms of the lower limb and improves its neuromuscular control. This functional improvement of the lower limb appears to be enhanced after ankle taping and kinesiology taping compared with elastic bandaging and controls.



#8 An Unusual Case of Arm Pain in a Young Soccer Player: Herpes Zoster in the Pediatric Athlete

Reference: Curr Sports Med Rep. 2022 Nov 1;21(11):386-390. doi: 10.1249/JSR.0000000000001005.

Authors: James MacDonald, Joy Mosser-Goldfarb, Cristina Tomatis Souverbielle, Steven Cuff

Summary: Herpes zoster (HZ), shingles, is caused by the varicella-zoster virus (VZV). HZ develops as a reactivation of latent VZV and is characterized by a painful, vesicular rash typically manifesting in a dermatomal distribution on the arms, trunk or face. HZ occurs in individuals who had primary VZV disease (chickenpox) as a child or in those who have received live, attenuated VZV vaccine. HZ is common in the elderly and the immunocompromised, with age being the single greatest risk factor. The incidence of HZ in children is 74/100,000 person years for the unvaccinated and 38/100,000 person years for the vaccinated. We discuss the case of a 12-year-old soccer player with HZ who presented with right arm pain after a putative traumatic event. Diagnosis was made after two emergency department visits where the condition was not identified. HZ should be considered in the clinician's differential even in immunocompetent, vaccinated children.



#9 Intensity demands and peak performance of elite soccer referees during match play

Reference: J Sci Med Sport. 2022 Oct 14;S1440-2440(22)00440-6.  doi: 10.1016/j.jsams.2022.10.006. 

Authors: Farzad Yousefian, Abdullah Zafar, Pedro Peres, João Brito, Bruno Travassos, Pedro Figueiredo

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Summary: This study examined the peak physical and physiological (heart rate) performance intensities andassociated decrements in elite soccer referees during match play. Physical performancevariables and heart rate were analyzed during 457 matches across two seasons. Differences between halves, and the rate ofdecline in peak performance intensities across moving average durations of 1-10 minutes were assessed using linear mixed models and power-law analysis, respectively. Large significant differences were observed between halves for mean total distance, mean velocity, mean heart rate, and percentage of maximal heart rate (p ≤ 0.05; r = 0.51-0.64). Peak intensities (p ≤ 0.05; r = 0.15-0.17) and the rate of decline (p < 0.001; r = 0.17-0.37) were significantly higher in the 2nd half compared to the 1st half, for relative total distance, relative high-intensity running and mean velocity. The rate of decline was significantly greater in the 2nd half than the 1st half for relative distance covered by high-intensity acceleration (>2 m/s-2/min), deceleration (<-2 m/s-2/min), and relative mean heart rate (p < 0.001; r = 0.28-0.61). Elite soccer referees might have experienced transient fatigue during match play, as relative high-intensity running immediately following the most intense 5-minute period significantly declined by 61.2% ( p< 0.001; r = 0.94), and was 16.2% lower than the mean 5-minute period (p < 0.001; r = 0.34). Increased physical and physiological demands during match play, with associated declines in the second half and transient signs of fatigue throughout the match, supports the inclusion of high-intensity interval and endurance training programs to prepare soccer referees for the intensity demands and peak performance outcomes of match play.



#10 Normalising the conversation: A qualitative analysis of player and stakeholder perceptions of menstrual health support within elite female soccer

Reference: Sci Med Footb. 2022 Nov 7. doi: 10.1080/24733938.2022.2145349. Online ahead of print.

Authors: Samuel J McHaffie, Carl Langan-Evans, James C Morehen, Juliette A Strauss, José L Areta, Christopher Rosimus, Martin Evans, Kirsty J Elliott-Sale, Colum J Cronin, James P Morton

Summary: This qualitative study explores player and stakeholder perceptions of menstrual health support in elite female soccer. Semi-structured interviews were conducted with 47 participants including players (n = 12), parents (n = 9), coaches (n = 9), sport scientists (n = 7), nutritionists (n = 5) and medical staff (n = 5). Via thematic analysis, data demonstrate that elite female soccer players experience a range of physical and psychological symptoms primarily at the onset of and during menses (as also perceived by stakeholders), with most participants perceiving these symptoms to impact performance. Nonetheless, menstrual health support is perceived as minimal and although players have their menstrual status tracked, they report little understanding as to why or how this information is used. This confusion was also present among stakeholders, often as a result of uncertainty about the evidence supporting the need for menstrual health support. The perceived lack of support may also be reflective of a culture where conversations about the menstrual cycle are not normalised. Overall, this may result in failure to identify and treat menstrual irregularities despite non-coaching staff members perceiving them to be common amongst players. These data support the need for individualised support based on the lived experiences of individual players and support staff. Furthermore, our research identifies the need for organisational, stakeholder, and player centred education programmes (led by experts in female athlete health) that create an environment where players receive personalised menstrual health support.



#11 Cerebral and cognitive modifications in retired professional soccer players: TC-FOOT protocol, a transverse analytical study

Reference: BMJ Open. 2022 Nov 9;12(11):e060459. doi: 10.1136/bmjopen-2021-060459.

Authors: Sabrina Kepka, François Lersy, Julien Godet, Frederic Blanc, Mathias Bilger, Anne Botzung, Catherine Kleitz, Jeanne Merignac, Emmanuel Ohrant, Franck Garnier, François Pietra, Vincent Noblet, Caroline Deck, Remy Willinger, Stéphane Kremer

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Summary: Soccer is the most popular sport in the world. This contact sport carries the risk of exposure to repeated head impacts in the form of subconcussions, defined as minimal brain injuries following head impact, with no symptom of concussion. While it has been suggested that exposure to repetitive subconcussive events can result in long-term neurophysiological modifications, and the later development of chronic traumatic encephalopathy, the consequences of these repeated impacts remain controversial and largely unexplored in the context of soccer players. This is a prospective, single-centre, exposure/non-exposure, transverse study assessing the MRI and neuropsychological abnormalities in professional retired soccer players exposed to subconcussive impacts, compared with high-level athletes not exposed to head impacts. The primary outcome corresponds to the results of MRI by advanced MRI techniques (diffusion tensor, cerebral perfusion, functional MRI, cerebral volumetry and cortical thickness, spectroscopy, susceptibility imaging). Secondary outcomes are the results of the neuropsychological tests: number of errors and time to complete tests. We hypothesise that repeated subconcussive impacts could lead to morphological lesions and impact on soccer players' cognitive skills in the long term. Ethics approval has been obtained and the study was approved by the Comité de Protection des Personnes (CPP) No 2021-A01169-32. Study findings will be disseminated by publication in a high-impact international journal. Results will be presented at national and international imaging meetings.



#12 Negative Impact of the UEFA European Soccer Championship on Central Hemodynamics and Arterial Stiffness: A Multicenter Study

Reference: Life (Basel). 2022 Oct 25;12(11):1696. doi: 10.3390/life12111696.

Authors: Klaas F Franzen, Kai Mortensen, Christian Ott, Katrin Herber, Marlene Busse, Charlotte Söling, Daniel Schneppe, Saskia Lässig, Marcus Dörr, Roland Tilz, Daniel Drömann, Heribert Schunkert, Michael Reppel

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Summary: Watching sporting events may trigger cardiovascular events by elevating emotional stress levels. The underlying reasons and specific populations at risk are not well defined.  We conducted a multicenter prospective trial at three German sites during the UEFA Soccer EC 2012 and 2021 comprising 52 healthy participants (noCVD) and 18 patients hospitalized with cardiovascular disease (CVD). Subjects were studied during matches of the German national team (GP) as well as corresponding matches without German participation (noGP). Peripheral and central blood pressure (BP) and parameters of arterial stiffness were measured (Mobil-O-Graph™, I.E.M., Stolberg, Germany) before, during, and after the matches. In terms of CVD, peripheral as well as central BP and heart rate increased significantly during GP as well as noGP matches and remained elevated beyond the end of the matches. Likewise, arterial stiffness parameters and vascular resistance were higher during the matches and remained elevated after the matches. No consistent significant differences were found between GP and noGP matches. This is the first study on real-life changes in hemodynamics during sport-associated emotional stress, with comparison between noCVD and CVD. We found that alterations were profound in CVD and remained elevated even after the matches.



#13 Plantar Fasciitis in Soccer Players-A Systemic Review

Reference: Int J Environ Res Public Health. 2022 Nov 3;19(21):14426. doi: 10.3390/ijerph192114426.

Authors: David C Noriega, Ángel Cristo, Alejandro León, Belén García-Medrano, Alberto Caballero-García, Alfredo Córdova-Martinez

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Summary: Soccer is one of the most popular sports in the world. Players often suffer a variety of injuries, the most common being injuries to muscles and tendons. It is striking that with soccer, being the most practiced sport, and considering that most injuries occur in the lower extremities, plantar fasciitis (PF) is not one of the most frequent injuries (at least in terms of clinical data collected). The purpose of this review was to provide a comprehensive update of the topic "plantar fasciitis" focusing on soccer players. The review was conducted in accordance with the PRISMA (Preferred Reportiog ltems for Systmiatic reviews and Meta-Analyses) statement. PubMed, Cochrane Library and Scopus were researched. PICO (Patient, Population or Problem; Intervention; Comparison; and Outcome) components were identified. The keywords used were "plantar fasciitis", "plantar fasciitis and sport", "plantar fasciitis risk factors", "plantar fasciitis soccer" and "plantar fasciitis football players". With respect to the objective proposed for the research, we found eight specific articles focused on soccer. Of these, five were general reviews discussing the different methods of treatment of this pathology, and we have only found three studies that focused on PF in soccer, with two of them referring to a clinical case whereby the report and discussion only dealt with the specific treatment followed by the soccer player. After reviewing the manuscripts included in this work, we were surprised that there is no data in which the Silfverskiöld test was performed, as this test explores the passive mobility of the ankle and the degree of dorsiflexion in the supine position. We concluded that soccer players suffer pain in the sole of the foot compatible with plantar fasciitis; however, as indicated by Suzue et al., it is often not diagnosed because the athlete does not consider performing the clinical examinations necessary for its diagnosis. The shortage of reported publications in soccer may mask other PF-associated injuries.



#14 Effects of a 9-weeks arch support intervention on foot morphology in young soccer players: a crossover study

Reference: BMC Sports Sci Med Rehabil. 2022 Nov 14;14(1):193. doi: 10.1186/s13102-022-00590-3.

Authors: Kohei Hikawa, Toshiharu Tsutsui, Takehiro Ueyama, Jin Yang, Yukina Hara, Suguru Torii

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Summary: A flat foot is a common cause of chronic sports injuries and therefore many opportunities for arch support interventions exist. However, young athletes change their foot morphology due to developmental influences even without intervention. Therefore, developmental influences need to be considered when examining the effects of arch support, but there have not been sufficient longitudinal studies to date. This study aimed to determine the effect of the arch support intervention by performing a 9-weeks arch support intervention on the foot morphology and cross-sectional area of the foot muscles in flat-footed young athletes. Thirty-one elementary school boys (Age 11.4 ± 0.5 years, Height 145.2 ± 7.4 cm, Weight 38.8 ± 8.3 kg, BMI 18.2 ± 2.2 kg/m2) with a decreased medial longitudinal arch in the foot posture index were selected as participants from a local soccer club and randomly divided into two groups. In one group, in the intervention period, an existing arch supporter was used to provide arch support, while in the other group, no special intervention was provided in the observation period. To account for developmental effects, the intervention study was conducted as an 18-weeks crossover study in which the intervention and observational phases were switched at 9 weeks after the intervention. Foot morphology was assessed using a three-dimensional foot measuring machine, and the cross-sectional area (CSA) of the internal and external muscles of the foot was assessed using an ultrasound imaging device. We examined the effect of the intervention by comparing the amount of change in the measurement results between the intervention and observation periods using corresponding t-tests and Wilcoxon signed-rank sum test, analysis of covariance methods. After adapting the exclusion criteria, 14 patients (28 feet) were included in the final analysis. The CSA of the abductor hallucis muscle (ABH) increased 9.7% during the intervention period and 3.0% during the observation period (p = 0.01). The CSA of the flexor digitorum longus muscle (FDL) increased 7.7% during the intervention period and 4.2% during the observation period (p = 0.02). A 9-weeks arch supporter intervention may promote the development of the ABH and FDL CSA in young flat-footed soccer players.



#15 Utilizing Soccer for Delivery of HIV and Substance Use Prevention for Young South African Men: 6-Month Outcomes of a Cluster Randomized Controlled Trial

Reference: AIDS Behav. 2022 Nov 15. doi: 10.1007/s10461-022-03819-x. Online ahead of print.

Authors: Stephan Rabie, Mark Tomlinson, Ellen Almirol, Jackie Stewart, Zwelibanzi Skiti, Robert E Weiss, Lodewyk Vogel, Mary Jane Rotheram-Borus

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Summary: Young men in South Africa face the intersecting epidemics of HIV, substance use and endemic poverty. We tested the effectiveness of a behavioral intervention using soccer training to reduce the cluster of risks associated with HIV and substance use. This cluster randomized controlled trial was conducted with men aged 18-29 years old in 27 neighborhoods in the townships of Cape Town, South Africa. Neighborhoods were randomized to receive for 6 months either: (1) Soccer League (SL; n = 18 neighborhoods, n = 778 men) who attended soccer three times weekly (72 sessions; 94% uptake, 45.5% weekly attendance rate), combined with an HIV/substance use, cognitive-behavioral intervention; or (2) a Control Condition (CC; n = 9; 415 men) who received educational materials and referrals at 3 month intervals. The primary outcome was the number of significant changes in a cluster of outcomes including HIV-related risks, substance abuse, employment/income, mental health, violence, and community engagement. There was only one significant difference on the rapid diagnostic tests for mandrax at 6 months, an insufficient number of changes to indicate a successful intervention. A group-based behavioral intervention was ineffective in addressing multiple risk behaviors among at-risk young men, similar to the findings of several recent soccer-related interventions. Early adulthood may be too late to alter well-established patterns of risk behaviors.Clinical Trial Registration This trial was prospectively registered on 24 November 2014 with NCT02358226.



#16 A randomised controlled trial of 1- versus 2-day per week formats of Nordic hamstring training on explosive athletic tasks in prepubertal soccer players

Reference: J Sports Sci. 2022 Nov 16;1-9. doi: 10.1080/02640414.2022.2145737. Online ahead of print.

Authors: Mahmoudi Abdelkader, Raouf Hammami, Ben Drury, Nicholas Clark, Gavin Sandercock, Ina Shaw, Brandon S Shaw, Sabri Gaied Chortane, Jason Moran

Summary: This randomised controlled trial examined the effect of volume-equated programmes of Nordic hamstring exercise (NHE) training, executed at frequencies of 1- or 2-days per week, on explosive athletic tasks (30 m sprint, 15 m manoeuvrability and standing long jump [SLJ]) in male youth soccer players (mean age: 10.3 ± 0.5 years). Players were divided into an experimental group (n = 31) which was further subdivided into 1-day (n = 16) and 2-days (n = 15) per week training conditions, and a control group (n = 14). There were significant group-by-time interactions for 30-m sprint (p < 0.001, d = 0.6), SLJ (p = 0.001, d = 1.27) and 15 m manoeuvrability (p < 0.001, d = 0.61). The experimental group demonstrated small to moderate effect sizes in 30-m sprint (d = 0.42, p = 0.077), SLJ (d = 0.97, p < 0.001) and 15 m manoeuvrability (d = 0.61, p < 0.001). The control group showed small significant performance decrements or no change in these variables. There were no significant differences between the 1-day and 2-day training groups. In two of the three tests (30 m sprint, SLJ) the 2-day group demonstrated larger effect sizes. The NHE enhances explosive athletic task performance in prepubertal youth soccer players and there may be only small advantages to spreading training over two days instead of one.



#17 Growth, maturation and injuries in high-level youth football (soccer): A mini review

Reference: Front Sports Act Living . 2022 Nov 1;4:975900. doi: 10.3389/fspor.2022.975900. eCollection 2022.

Author: Eirik Halvorsen Wik

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Summary: Understanding the challenges football (soccer) players face during adolescence is fundamental to avoid disruptions in their development due to injury. This mini review will describe basic concepts of somatic growth and biological maturity, examine data from 53 prospective epidemiological studies on high-level youth football players and discuss how age, growth and maturity may affect the injury patterns observed. Based on the existing evidence, at least every third player sustains an injury during a football season. The thigh (median for studies of boys: 25%, median for girls: 21%), ankle (b: 18%, g: 30%), knee (b: 17%, g: 18%) and hip/groin (b: 14%, g: 10%) are the body parts injured most often, while muscle strains (b: 31%, g: 25%), sprains (b: 20%, g: 27%) and contusions (b: 17%, g: 16%) are the most common injury types. Injury trends are, however, not consistent throughout adolescence, and players' age, maturity status and position relative to peak height velocity (PHV) have shown to influence the number, type and location of injuries sustained. Despite a high volume of observational injury studies published on high-level youth players, girls (7 studies) and settings outside of Europe (included in 23% of studies) are underrepresented and should receive extra attention in the future. Based on the available epidemiological data, tailored injury reduction programmes can be considered in youth football, alongside application of general training principles such as progression, variation and individualization which may be especially important during vulnerable phases such as the adolescent growth spurt.






Training elite youth soccer players: area per player in small-sided games to replicate the match demands

The aim was to determine the area per player (ApP) in small- (SSG) or large-sided games (LSG) to replicate the official match demands in elite youth soccer players.





Effect of an Energy Drink On Muscle and Liver Damage Enzymes, And Cardiovascular Indices in Soccer Players

This study aimed to investigate the acute effects of hype energy drink (HED) to ameliorate liver and muscle damage enzymes and cardiovascular indices-induced by a soccer match.





2022 FIFA World Cup Pocket Guide

Due to the positive feedback the "Pocket Guide" has earned from the UEFA European Championship 2012 and the previous 2014 FIFA World Cup in Brazil, I have also prepared one for the upcoming 2022 FIFA World Cup.


It can be downloaded for Central European Time (CET) below.


The download consists of two pages. The first one displays the date, time and location of all games and the second one displays the introduction how to cut and fold the paper.


footballscience 2022 WC pocket guide
footballscience 2022 wc pocket guide.pdf
Adobe Acrobat Document 5.3 MB





FIFA 2022 World Cup Players and Teams transfer value

The FIFA 2022 World Cup is about to kick off and it feels interesting to have a closer look on the estimated transfer value running around on the pitch.

From a national perspective it can be stated that England sits at the top with €1.499 bio in estimated transfer values followed by Brazil (€1.455 bio) as the second highest. France (€1.337 bio), Spain (€1.201 bio) and Portugal (€1.154 bio) are located at places 3 to 5 respectively by the CIES Football Observatory. The following graph indicates the Top 30 teams and their players' estimated transfer value.



Broken down to a club level, Bayern Munich had to release the most players attending the FIFA 2022 World Cup with a total of 17 players. ManCity and Barcelona FC are in 2nd and 3rd place with each 16 players completing the top 3 teams. The following graph shows the Top Ten (more or less) teams. 



On an individual players level it can be seen that from the total of 831 players, Borussia Dortmund’s Jude Bellingham inheriting the top estimated transfer value (€202 mio.) among all World Cup players, followed by Real Madrid’s Vinícius Junior (€200 mio.), Mbappe (PSG €185 mio.), Gonzalez (Barcelona €158 mio.) and Musiala (Bayern €151 mio.) completing the top 5. The following graphs shows the Top 30 players from the 2022 FIFA World Cup.











High-speed Training in a Specific Context in Soccer: Transition Games

The aims of this study were to compare the load of three tasks designed to train features of soccer: a transition game (TG), a small sided game (SSG) with a change of playing area, and a large-sided game (LSG).





When and how do professional soccer players experience maximal intensity sprints in LaLiga?

The purpose was to 1) examine the periods in which maximal intensity sprints occurred and 2) analyze the maximal intensity sprints registered in match play considering the effect of playing position and other contextual variables.





Latest research in football - week 43 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 An evidence-based approach to assessing the effectiveness of training regimen on athlete performance: Youth soccer as a case study

Reference: PLoS One. 2022 Nov 1;17(11):e0276762. doi: 10.1371/journal.pone.0276762. eCollection 2022.

Authors: Cam M K Rechenmacher, Michael Keating, James D Nichols, Jonathan M Nichols

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Summary: Athletic performance data are modeled in an effort to better understand the relationship between both hours spent training and a measurement of "commitment" to that training, and improvements in performance. Both increased training time and greater commitment were predicted to produce larger increases in performance improvement, and commitment was predicted to be the more important determinant of improvement. The performance of 108 soccer players (ages 9-18) was quantified over a 10-week training program. Hours spent training ranged from 16 to 90 during the course of the study, while commitment scores ranged from 0.55 to 2.00, based on a scale from 0.00 to 2.40. A model selection approach was used to discriminate among models specifying relationships between training hours and improvement, and commitment and improvement. Despite considerable variability in the data, results provided strong evidence for an increase in performance improvement with both training hours and commitment score. The best models for hours and commitment were directly compared by computing an evidence ratio of 5799, indicating much stronger evidence favoring the model based on commitment. Results of analyses such as these go beyond anecdotal experience in an effort to establish a formal evidentiary basis for athletic training programs.



#2 Effects of long-term detraining on muscle performance in young soccer players

Reference: J Sports Med Phys Fitness. 2022 Nov 2. doi: 10.23736/S0022-4707.22.13948-4. Online ahead of print.

Authors: Giovanni Melchiorri, Valerio Viero, Daniele Lentini, Giuseppe Annino, Virginia Tancredi, Tamara Triossi

Summary: Long-term detraining consists of a physiological partial or total reduction of the adaptations induced by training caused by a suspension period of the training itself longer than 4 weeks. The aim of this study was to analyze a group of young soccer players by assessing the effects of long-term detraining on neuromuscular performance. A study sample of 35 young soccer players of sub-elite level (age 14.5 ± 0.5 years) was recruited. The subjects were tested 7 days before the interruption of training for the summer break (T0), and at the end of the 7-week detraining period (T1). No statistically significant differences were found for BMI (p=0.283) and percentage of fat mass (p=0.273) between T0 and T1. PUSH UP (p=0.016; ES=effect size 0.2) and SIT UP (p=0.001; ES 1.2) test values show statistically significant increase, those of CHIN UP (p=0.05; ES -0.2), instead, a statistically significant worsening. Statistically significant but moderate differences on Speed Running Test 30 meters (p=0.001; ES: 0.3) are observed as well as trivial differences on 50 meters (p=0.001; ES: 0.2), while differences on 10, 15 and 20 meters are irrelevant. As for the jump tests, values show a slight worsening (p=0.135; ES 0.2) in Squat Jump and Counter Movement Jump (p=0.153; ES 0.2) without statistical significance. A 7-week-long detraining period does not seem to produce any appreciable changes on neuromuscular performance of the lower limb (trained muscle) in young soccer players. As regards the analyzed age group, coaches should not focus their attention on neuromuscular efficiency maintenance exercises in the off-season period.



#3 Penalty feet positioning rule modification and laterality effect on soccer goalkeepers' diving kinematics

Reference: Sci Rep. 2022 Nov 2;12(1):18493. doi: 10.1038/s41598-022-21508-6.

Authors: Rafael Luiz Martins Monteiro, Bruno Luiz Souza Bedo, Pedro Henrique Martins Monteiro, Felipe Dos Santos Pinto de Andrade, Felipe Arruda Moura, Sergio Augusto Cunha, Ricardo da Silva Torres, Daniel Memmert, Paulo Roberto Pereira Santiago

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Summary: In 2019, a new rule was applied in soccer. It allows the goalkeeper to have only one foot or part of it on the goal line when the kicker hits the ball, unlike the previous rule that determined the goalkeeper should have both feet on the line. The purpose of the present study was to analyze how the change in the rule and the lower limbs laterality influences on the diving save kinematic performance in penalties. Six goalkeepers, two professionals and four amateurs, performed a total of 20 dives in the laboratory and had their force and impulse exerted by the lower limb and displacement/velocity data from the center of body mass collected through force plates and kinematic analysis. The side preference was collected through an inventory. The results showed that goalkeepers dive further (p < 0.001) and faster (p < 0.001) when diving according to the new rule. Dives for the non-dominant side presented higher values than the trials for the dominant side in mediolateral (p = 0.02) and resultant (p = 0.03) displacements. Concluding, the goalkeepers performed better with the new rule in the analyzed variables and the lower limb preference has influenced only the mediolateral and resultant displacement.



#4 Preliminary results indicate that regular training induces high protection against oxidative stress in basketball players compared to soccer

Reference: Sci Rep. 2022 Nov 2;12(1):18526. doi: 10.1038/s41598-022-23351-1.

Authors: Simone Luti, Rosamaria Militello, Tania Fiaschi, Francesca Magherini, Tania Gamberi, Matteo Parri, Riccardo Marzocchini, Simone Pratesi, Riccardo Soldaini, Alessandra Modesti, Pietro A Modesti

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Summary: In elite athlete several metabolic changes occur during regular training. These modifications are associated with changes in blood metabolic profile and can lead to adaptive mechanisms aimed at establish a new dynamic equilibrium, which guarantees better performance. The goal of this study was to characterize the plasma metabolic profile and redox homeostasis, in athletes practicing two different team sports such as soccer and basketball in order to identify potential metabolic pathways underlying the differences in training programs. A cohort of 30 male, 20 professional players (10 soccer and 10 basketballs) and 10 sedentary males as control were enrolled in the study. Plasma redox balance, metabolites and adiponectin were determined. The results show low levels of oxidative species (25.5%), with both high antioxidant capacity (17.6%) and adiponectin level (64.4%) in plasma from basketball players, in comparison to soccer players. Metabolic analysis indicates in basketball players a significant high plasma level of amino acids Valine and Ornithine both involved in redox homeostasis and anti-inflammatory metabolism.



#5 Two-dimensional and three-dimensional multiple object tracking learning performance in adolescent female soccer players: The role of flow experience reflected by heart rate variability

Reference: Physiol Behav. 2022 Oct 29;258:114009. doi: 10.1016/j.physbeh.2022.114009. Online ahead of print.

Authors: Xiang Che, Yu Zhang, Jingkang Lin, Kun Zhang, Weiqun Yao, Jijun Lan, Jie Li

Summary: Three-dimensional multiple object tracking (3D-MOT) has been used in various fields to mimic real-life tracking, especially in perceptual-cognitive skills training for soccer. Yet, the learning efficiency in 3D-MOT tasks has not been compared with 2D-MOT. Further, whether the advantage can be reflected by heart rate variability (HRV) based on the neurovisceral integration model should also be examined. Therefore, we used both 2D- and 3D-MOT in a brief adaptive task procedure for adolescent female soccer players with HRV measurement. A faster tracking speed threshold of participants was found in the 3D- compared to 2D-MOT, as well as average tracking speed in the last training period of 3D-MOT. Moreover, lower low frequency (LF) components of HRV in the 3D-MOT indicated a flow experience, demonstrating the provision of more attentional resources. Therefore, we observed that adolescent female soccer players demonstrated higher learning efficiency in 3D-MOT tasks in virtual reality (VR) through a higher flow experience. This study examined the learning efficiency between the two MOT tasks in the soccer domain using evidence from HRV and highlighted the utility and applicability of 3D-MOT application.



#6 Quantifying Exposure and Intra-Individual Reliability of High-Speed and Sprint Running During Sided-Games Training in Soccer Players: A Systematic Review and Meta-analysis

Reference: Sports Med. 2022 Nov 4. doi: 10.1007/s40279-022-01773-1. Online ahead of print.

Authors: Antonio Dello Iacono, Shaun J McLaren, Tom W Macpherson, Marco Beato, Matthew Weston, Viswanath B Unnithan, Tzlil Shushan

Summary: Sided games (i.e., small sided, medium sided, large sided) involve tactical, technical, physical, and psychological elements and are commonly implemented in soccer training. Although soccer sided-games research is plentiful, a meta-analytical synthesis of external load exposure during sided games is lacking. The objective of this systematic review and meta-analysis was to: (1) synthesize the evidence on high-speed and sprint running exposure induced by sided games in adult soccer players, (2) establish pooled estimates and intra-individual reliability for high-speed and sprint running exposure, and (3) explore the moderating effects of game format and playing constraints. A literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Four databases (PubMed/MEDLINE, Scopus, SPORTDiscus, Web of Science Core Collection) were systematically searched up to 25 January, 2022. Eligibility criteria were adult soccer players (population); training programs incorporating sided games (intervention); game manipulations including number of players, pitch dimension, and game orientation (comparator); and high-speed, very high-speed, and sprint relative (m[Formula: see text]min-1) running distances and associated intra-individual reliability (outcome). Eligible study risk of bias was evaluated using RoBANS. Pooled estimates for high-speed and sprint running exposure, and their intra-individual reliability, along with the moderating effect of tracking device running velocity thresholds, pitch dimension (i.e., area per player), and game orientation (i.e. score or possession), were determined via a multi-level mixed-effects meta-analysis. Estimate uncertainty is presented as 95% compatibility intervals (CIs) with the likely range of relative distances in similar future studies determined via 95% prediction intervals. A total of 104 and 7 studies met our eligibility criteria for the main and reliability analyses, respectively. The range of relative distances covered across small-sided games, medium-sided games, and large-sided games was 14.8 m[Formula: see text]min-1 (95% CI 12.3-17.4) to 17.2 m[Formula: see text]min-1 (95% CI 13.5-20.8) for high-speed running, 2.7 m[Formula: see text]min-1 (95% CI 1.8-3.5) to 3.6 m[Formula: see text]min-1 (95% CI 2.3-4.8) for very high-speed running, and 0.2 m[Formula: see text]min-1 (95% CI 0.1-0.4) to 0.7 m[Formula: see text]min-1 (95% CI 0.5-0.9) for sprinting. Across different game formats, 95% prediction intervals showed future exposure for high-speed, very high-speed running, and sprinting to be 0-46.5 m[Formula: see text]min-1, 0-14.2 m[Formula: see text]min-1, and 0-2.6 m[Formula: see text]min-1, respectively. High-speed, very high-speed running, and sprinting showed poor reliability with a pooled coefficient of variation of 22.8% with distances being moderated by device speed thresholds, pitch dimension, and game orientation. This review is the first to provide a detailed synthesis of exposure and intra-individual reliability of high-speed and sprint running during soccer sided games. Our estimates, along with the moderating influence of common programming variables such as velocity thresholds, area per player, and game orientation should be considered for informed planning of small-sided games, medium-sided games, and large-sided games soccer training.



#7 Individual-Specific Relationship Between External Training and Match Load and Creatine-Kinase Response in Youth National Team Soccer Players

Reference: Sports Health. 2022 Oct 30;19417381221128822. doi: 10.1177/19417381221128822.

Authors: Gabor Schuth, Gyorgy Szigeti, Gergely Dobreff, Alija Pasic, Tim Gabbett, Adam Szilas, Gabor Pavlik

Summary: Previous studies have examined the relationship between external load and creatine-kinase (CK) response at the team level. This study aimed to build individualized CK prediction models for elite youth national team soccer players. We hypothesized that the CK response of youth soccer players can be categorized as being sensitive to micromovements (MM), high-velocity (HV) parameters, or the combination of both, measured during training sessions and matches. A total of 25 U16-U17 youth national team soccer players were monitored during training sessions and matches using global positioning system (GPS) units. Individual CK values were measured every morning from whole blood. The data set consisted of 57 ± 17 individual datapoints per player. Individual prediction models were used to examine the relationship between external load and consecutive CK changes. Numerous models were built for each player using MM, HV parameters, or the combination of both. The performance of the models was described by the R2 and the root mean square error (RMSE, U/l for CK values). The MM models were superior for 8 players (R2 = 0.68; RMSE = 113 U/l), followed by HV (8 players; R2 = 0.69; RMSE = 88 U/l) and the combined models (2 players; R2 = 0.64; RMSE = 141 U/l). For the remaining 7 players, the R2 of the models was <0.5. The recovery time between efforts was more important in the HV model. Players could be categorized on sensitivity to MM, HV movements, or the combination of both. These findings can be used to individualize postmatch recovery strategies and to optimize weekly training periodization to maximize match performance.



#8 A review of the essential visual skills required for soccer: Beyond 20-20 optometry

Reference: Front Sports Act Living. 2022 Oct 12;4:965195. doi: 10.3389/fspor.2022.965195. eCollection 2022.

Authors: Lourens Millard, Gerrit Jan Breukelman, Nonkululeko Mathe, Ina Shaw, Brandon S Shaw

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Summary: In ball sports such as soccer, the visual system is critical in guiding a player's search for crucial information that underpins skillful behavior, which requires the incorporation of all of the relevant information in the environment in order to make successful decisions under pressure. However, vision in sport, and focusing on the specific visual skills required to be successful in a particular sport has largely been a practice ignored by experts and coaches as being an essential component of athletic performance. This is the first attempt to summarize and compile the necessary visual skills for soccer. This review's evidence suggests that, while current research still tends to focus on visual skills as a whole, there is a need to streamline this focus to the necessities of a particular sport. Furthermore, in identifying the visual skills essential for soccer, it allows for the effective training and testing of these skills, as well as for talent identification.



#9 Positive association of lean mass and negative association of protein intake on bone mass and bone geometry of adolescent soccer players

Reference: Nutrition. 2022 Sep 30;105:111857.  doi: 10.1016/j.nut.2022.111857. Online ahead of print.

Authors: Raiany Rosa Bergamo, Mauro Alexandre Páscoa, Jefferson Eduardo Hespanhol, Anderson Marques de Moraes, Gil Guerra-Júnior

Summary: The aim of this study was to evaluate the association of food consumption and body composition on bone parameters in adolescent soccer players. There were 148 male soccer players 12 to 18 y who participated in the study. Body composition was assessed by dual energy x-ray absorptiometry, comprising bone mineral density (BMD) and bone mineral content (BMC) of total body without head (TBLH), lumbar spine (L1-L4), and right femoral neck (RFN). The bone geometry variables measured were femoral strength index (FSI), buckling ratio (BR), section modulus (Z), cross-sectional moment of inertia (CSMI), and cross-sectional area (CSA). Food intake was analyzed using the 24-h food recall. Somatic maturation was estimated by the peak height velocity equation. For the statistical analysis, the stepwise multiple linear regression was used, with P < 0.05. Regarding food consumption, there was a high protein intake and low calcium intake. Lean mass was a predictor of BMC of TBLH (R2 = 0.524), L1-L4 (R2 = 0.492), and RFN (R2 = 0.405); BMD of L1-L4 (R2 = 0.407) and RFN (R2 = 0.27); Z (R2 = 0.683), CSMI (R2 = 0.630), and CSA (R2 = 0.640). There was a negative correlation between protein intake with bone mass and bone geometry parameters. In adolescent soccer players, lean mass was a predictor of bone parameters, and high protein intake was negatively associated with bone mass and geometry.



#10 A neural network for the detection of soccer headers from wearable sensor data

Reference: Sci Rep. 2022 Oct 28;12(1):18128. doi: 10.1038/s41598-022-22996-2.

Authors: Jan Kern, Thomas Lober, Joachim Hermsdörfer, Satoshi Endo

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Summary: The aim was to investigate the proposed association between soccer heading and deleterious brain changes, an accurate quantification of heading exposure is crucial. While wearable sensors constitute a popular means for this task, available systems typically overestimate the number of headers by poorly discriminating true impacts from spurious recordings. This study investigated the utility of a neural network for automatically detecting soccer headers from kinematic time series data obtained by wearable sensors. During 26 matches, 27 female soccer players wore head impacts sensors to register on-field impact events (> 8 g), which were labelled as valid headers (VH) or non-headers (NH) upon video review. Of these ground truth data, subsets of 49% and 21% each were used to train and validate a Long Short-Term Memory (LSTM) neural network in order to classify sensor recordings as either VH or NH based on their characteristic linear acceleration features. When tested on a balanced dataset comprising 271 VHs and NHs (which corresponds to 30% and 1.4% of ground truth VHs and NHs, respectively), the network showed very good overall classification performance by reaching scores of more than 90% across all metrics. When testing was performed on an unbalanced dataset comprising 271 VHs and 5743 NHs (i.e., 30% of ground truth VHs and NHs, respectively), as typically obtained in real-life settings, the model still achieved over 90% sensitivity and specificity, but only 42% precision, which would result in an overestimation of soccer players' true heading exposure. Although classification performance suffered from the considerable class imbalance between actual headers and non-headers, this study demonstrates the general ability of a data-driven deep learning network to automatically classify soccer headers based on their linear acceleration profiles.



#11 Extended Knee Control programme lowers weekly hamstring, knee and ankle injury prevalence compared with an adductor strength programme or self-selected injury prevention exercises in adolescent and adult amateur football players: a two-armed cluster-randomised trial with an additional comparison arm

Reference: Br J Sports Med. 2022 Oct 31;bjsports-2022-105890. doi: 10.1136/bjsports-2022-105890.

Authors: Hanna Lindblom, Sofi Sonesson, Kalle Torvaldsson, Markus Waldén, Martin Hägglund

Summary: The aim was to evaluate the preventive efficacy of an extended version of the Knee Control injury prevention exercise programme (IPEP) compared with an adductor strength programme and to a comparison group using a self-selected IPEP in amateur adolescent and adult male and female football players. Two-armed cluster-randomised trial with an additional non-randomised arm. All 251 amateur teams (players 14-46 years) in one regional football district were approached. Teams meeting inclusion criteria were randomised to (1) extended Knee Control or (2) an adductor strength programme. Teams already using an IPEP were allocated to a comparison group and received no new intervention. Players responded to weekly questionnaires about football exposures and injuries during a 7-month season. Seventeen teams in the extended Knee Control, 12 in the adductor and 17 in the comparison group participated, with 502 players. For the primary outcomes, no difference in injury incidence in three lower-limb injury locations combined (hamstring, knee and ankle) was seen between extended Knee Control and the adductor group, whereas extended Knee Control had 29% lower incidence than the comparison group (incidence rate ratio 0.71, 95% CI 0.52 to 0.98). No between-group differences in groin injury incidence were seen. The weekly injury prevalence rates in the three lower limb locations combined (hamstring, knee and ankle) were 17% lower (prevalence rate ratio (PRR) 0.83, 95% CI 0.69 to 1.00) and 26% lower (PRR 0.74, 95% CI 0.63 to 0.87) in extended Knee Control compared with the adductor and comparison groups, respectively. No difference in injury incidence was seen between the extended Knee Control and the adductor programme whereas extended Knee Control reduced injury incidence by nearly one-third compared with a self-selected IPEP. Players in extended Knee Control had lower injury prevalence compared with an adductor or self-selected IPEP.



#12 "Benched" The effect of the COVID-19 lockdown on injury incidence in sub-elite football in Australia: A retrospective population study using injury insurance records

Reference: Sci Med Footb. 2022 Nov 3. doi: 10.1080/24733938.2022.2143551. Online ahead of print.

Authors: Andrew G Ross, Marnee J McKay, Evangelos Pappas, Nazim Bhimani, Kerry Peek

Summary: The primary aim of this study was to compare injury rates pre- and post- COVID-19 lockdown in sub-elite football (soccer) players by analysing the full season and the first month of each season between 2018-2020. Secondary aims were to describe the incidence, location and type of injuries and to compare injuries by age group and sex. A de-identified insurance database was retrospectively coded using the Orchard Sports Injury Classification System. Injury incidence per 1000 hours as well as incidence rate ratios (IRR) with confidence intervals were calculated. No significant difference was found in the overall incidence rate in 2020 compared with the 2018 and 2019 seasons (IRR, 1.04 [95% CI, 0.96-1.13]; p= 0.294). However, overall injuries increased by 26% (IRR: 1.26 [95% CI 1.07- 1.47]; p<0.005) and joint sprains increased by 45% (IRR: 1.45 [95% CI 1.14- 1.84]; p<0.005) in the first month of 2020 compared with 2018-2019. Between 2018-2020 there were 4149 injury insurance claims, with anterior cruciate ligament (ACL) ruptures accounting for 19% of all injuries. When comparing sex, female players had significantly more ankle sprains whilst male players suffered more dental injuries. This study adds to a growing body of evidence investigating injury rates post COVID-19 lockdowns in sport. Sub-elite players appear to be at higher risk of joint injuries within the first month of training following a period of lockdown. Overall, stakeholders involved in sub-elite football should prioritise knee and ankle joint injury prevention.



#13 Injury-Inciting Activities in Male and Female Football Players: A Systematic Review

Reference: Sports Med. 2022 Oct 31. doi: 10.1007/s40279-022-01753-5. Online ahead of print.

Authors: Francesco Aiello, Franco M Impellizzeri, Susan J Brown, Andreas Serner, Alan McCall

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Summary: A comprehensive examination of the sport-specific activities performed around the time of injury is important to hypothesise injury mechanisms, develop prevention strategies, improve management, and inform future investigations. The aim of this systematic review is to summarise the current literature describing the activities performed around the time of injury in football (soccer). A systematic search was carried out in PubMed, Web of Science, SPORTDiscus, and OpenGrey. Studies were included if participants were football players aged > 13 years old and the activities performed at the time of injury were reported together with the total number of injuries. Risk of bias was assessed using an adapted version of checklists developed for prevalence studies. The activities reported by the studies were grouped to account for inconsistent reporting, and the proportion of each injury activity was calculated. Data were not meta-analysed due to high heterogeneity of methods and classification criteria. We included 64 studies reporting on 56,740 injuries in total. ACL injures were analysed by 12 studies, ankle/foot and knee injuries were analysed by five studies, thigh injuries were analysed by four studies, hip/groin injuries were analysed by three studies, and hamstring injuries were analysed by two studies. Five studies analysed more than one type of injury and 38 studies did not specify the type of injuries analysed. Running and kicking were the predominant activities leading to thigh and hamstring injuries. Changing direction and kicking were the predominant activities leading to hip and groin injuries and duels were the predominant activities leading to ankle injuries. Duels and pressing seem the predominant activities leading to ACL injuries, while results for other knee and general injuries were inconsistent. A qualitative summary of the activities performed at the time of injury has been reported. The results need to be interpreted carefully due to the risk of bias observed in the included studies. If we are to meaningfully progress our knowledge in this area, it is paramount that future research uses consistent methods to record and classify injuries and activities leading up to and performed at the time of injury.



#14 Examining karate and football perceptions and their links with athlete engagement and quality of life

Reference: Front Sports Act Living. 2022 Oct 13;4:971677. doi: 10.3389/fspor.2022.971677. eCollection 2022.

Authors: Teresa Limpo, Gabriela Rödel, Sid Tadrist

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Summary: The importance of perceptions as determinants of people's behavior has been well-established, but little is known about athletes' perceptions of their sport and the links of these perceptions with other correlates. In this study, we compared karate (n = 51) and football (n = 49) athletes' perceived benefits and aggressiveness risks from their sports and examined whether these perceptions predicted athletes' engagement and quality of life (QoL). Participants completed perception measures of karate and football, and engagement and QoL measures. Results showed that karateka perceived more benefits and fewer risks in karate than football, but footballers generally perceived equal benefits and risks in both sports. Both athlete groups perceived similar physical and psychological benefits in their own sport, but deemed physical benefits as prominent outcomes in the other sport. Notably, karateka's perceived benefits about karate predicted engagement directly and QoL indirectly via vigor. Overall, karate athletes' perceptions seemed to be relevant to experiencing fulfillment in training and general well-being.



#15 Shortcomings of applying data science to improve professional football performance: Takeaways from a pilot intervention study

Reference: Front Sports Act Living. 2022 Oct 12;4:1019990. doi: 10.3389/fspor.2022.1019990. eCollection 2022.

Authors: Mat Herold, Matthias Kempe, Ludwig Ruf, Luis Guevara, Tim Meyer

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Summary: Positional tracking data allows football practitioners to derive features that describe patterns of player behavior and quantify performance. Existing research using tracking data has mostly focused on what occurred on the pitch, such as the determinants of effective passing. There have yet to be studies attempting to use findings from data science to improve performance. Therefore, 24 professional players (mean age = 21.6 years, SD = 5.7) were divided into a control team and an intervention team which competed against each other in a pre-test match. Metrics were gathered via notational analysis (number of passes, penalty box entries, shots on goal), and positional tracking data including pass length, pass velocity, defensive disruption (D-Def), and the number of outplayed opponents (NOO). D-Def and NOO were used to extract video clips from the pre-test that were shown to the intervention team as a teaching tool for 2 weeks prior to the post-test match. The results in the post-test showed no significant improvements from the pre-test between the Intervention Team and the Control Team for D-Def (F = 1.100, p = 0.308, η2 = 0.058) or NOO (F = 0.347, p = 0.563, η2 = 0.019). However, the Intervention Team made greater numerical increases for number of passes, penalty box entries, and shots on goal in the post-test match. Despite a positive tendency from the intervention, results indicate the transfer of knowledge from data science to performance was lacking. Future studies should aim to include coaches' input and use the metrics to design training exercises that encourage the desired behavior.







Cold Water Immersion Improves the Recovery of Both Central and Peripheral Fatigue Following Simulated Soccer Match-Play

The study aimed to investigate the effect of cold water immersion (CWI) on the recovery of neuromuscular fatigue following simulated soccer match-play.






The Influence of Weekly Sprint Volume and Maximal Velocity Exposures on Eccentric Hamstring Strength in Professional Football

The purpose was to examine the relationship between sprinting and eccentric hamstring strength by monitoring total weekly sprint distance and weekly efforts > 90% and >95% of maximum velocity (VMax).





Latest research in football - week 42 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Decline in Running Performance in Highest-Level Soccer: Analysis of the UEFA Champions League Matches

Reference: Biology (Basel). 2022 Oct 1;11(10):1441. doi: 10.3390/biology11101441.

Authors: Toni Modric, Sime Versic, Dan Iulian Alexe, Barbara Gilic, Ilie Mihai, Patrik Drid, Nikola Radulovic, Jose M Saavedra, Rafael Burgueño Menjibar

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Summary: It is widely recognized that there is a decline in match running performance (MRP) towards the end of matches. To clarify whether it is primarily a consequence of fatigue, pacing or situational influences, this study aimed to examine MRP across 15-min match periods for players on different playing positions. Players' MRP (n = 244) were examined from the UEFA Champions League matches (n = 20) using a semiautomatic optical tracking system. Linear mixed models for repeated measures were adjusted to analyze MRP over the six 15-min match periods while controlling the influence of situational factors. No effects of match outcome, match location, team, and opponent quality on total distance (TD) and high-intensity running (HIR) for players in all playing positions were found (F = 0.03-2.75; all p &gt; 0.05). Significant differences in TD (F = 17.57-53.01; η2 = 0.39-0.52, all large effect sizes) and HIR (F = 3.67-7.64; η2 = 0.05-0.19, small to medium effect sizes) among six 15-minute match periods were found for players in all playing positions. In addition, players in all playing positions covered less TD (d = 1.41-2.15, large to very large effect sizes) and HIR (d = 0.16-0.6, trivial to medium effect sizes) in the last compared to the first 15-min match period. No differences in TD and HIR between the last two match periods in the second half were observed. This study confirmed that soccer players reduce MRP towards the end of matches, and suggest that the decline of MPR in highest-level soccer may be a consequence of pacing strategies.



#2 Effects of perceptual-cognitive tasks on inter-joint coordination of soccer players and ordinary college students

Reference: Front Psychol. 2022 Oct 5;13:892118. doi: 10.3389/fpsyg.2022.892118. eCollection 2022.

Authors: Yuanyuan Ren, Cenyi Wang, Aming Lu

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Summary: Perceptual-cognitive tasks play a pivotal role in performing voluntary movements, which is crucial for good performances among soccer players. This study explored the effect of perceptual-cognitive tasks on the inter-joint coordination of soccer players and college students during landing. The classic multiple objective tracking (MOT) task was used to simulate the perceptual-cognitive task under a sports environment. Fifteen soccer players (age: 20.1 ± 1.5 year, height: 181.4 ± 7.4 cm, weight: 75.4 ± 10.7 kg) and twenty ordinary college students (age: 20.0 ± 2.3 years, height: 177.9 ± 4.9 cm, weight: 71.6 ± 9.9 kg) were enrolled to the study. Participants in the two groups were subjected to a single task (landing task) and dual-task (MOT task and landing task). Coordination and variability indicators were recorded using a Vicon infrared motion capture system and a force measuring platform. The results showed that the mean absolute relative phase of hip and knee joint (MARPhip-knee), deviation phase of hip and knee joint (DPhip-knee), and deviation phase of knee and ankle joint (DPknee-ankle) of the two groups under the dual-task were significantly different compared with the parameters when participants were subjected to the single task. The dual-task had higher effect size on DPhip-Knee and MARPhip-knee, indicating that dual-task had a greater impact on coordination of the hip and knee joints. DPhip-knee and DPknee-ankle of ordinary students were more extensive relative to those of the soccer players, and hip joint stiffness (K hip) for ordinary students was lower than that of the soccer players under the different tasks. These findings implied that the perceptual-cognitive task markedly affected the inter-joint coordination of soccer players and college students, mainly by impairing the hip and knee coordination. Although there is less variability in lower extremity coordination patterns of soccer players compared to college students, the MOT task still affects their coordination ability.



#3 Meniscal lesion or patellar tendinopathy? A case report of an adolescent soccer player with knee pain

Reference: J Can Chiropr Assoc. 2022 Aug;66(2):157-171.

Author: Antonio Petrolo

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Summary: Injuries to the meniscus are particularly prevalent in soccer players, with an incidence of 0.448 injuries per 1000 hours of playing. However, in the adolescent soccer player population, it has been reported that up to 63% of asymptomatic knees may demonstrate horizontal or oblique tears on MRI. These results may negatively influence clinical decision-making and plan of management for adolescent soccer players with knee problems. A case of a 15-year-old soccer player is presented after having been diagnosed by his family physician with a left lateral meniscus tear as per MRI, following a 10-week period of anterior knee pain. He presented to a chiropractor for a second opinion before consulting with the orthopedic surgeon. Recommendations for progressive rehabilitation owing to the lack of clinical evidence for meniscal abnormality were made. A primary diagnosis of left patellar tendinopathy was determined and after a 6-week comprehensive rehabilitation program, the patient made a complete recovery. A thorough history, physical examination, and understanding of the patient's injury mechanism are suggested before confirming/refuting suspicions of meniscal abnormalities via MRI. This will help to inform better clinical decision-making as well as decrease the occurrence of unnecessary imaging.



#4 Does a 40-week Football and Zumba exercise intervention influence self-reported job satisfaction, work role functioning and sick leave among female hospital employees? A cluster-randomised controlled trial

Reference: Eur J Sport Sci. 2022 Oct 28;1-21. doi: 10.1080/17461391.2022.2139634. Online ahead of print.

Authors: Svein Barene, Peter Krustrup, Andreas Holtermann

Summary: This 40-week cluster-randomized controlled trial (RCT) examines the effects of football and Zumba on self-perceived job satisfaction, work role functioning and sick leave among Norwegian female hospital employees. Hundred-and-seven employees, mainly consisting of nurses (80%), were allocated into three groups; Football (FG), Zumba (ZG) and Control (CG). The exercise groups were offered 2-3 and 1-2 one-hour weekly sessions during the first 12 and last 28 weeks, respectively, with an actual weekly exercise frequency of 2.4 ± 0.5 and 0.9 ± 0.2 in FG and 2.3 ± 0.3 and 0.8 ± 0.2 in ZG. Outcome variables were measured at baseline, 12 and 40 weeks. In comparison to CG (4.8 days 95% CI 3.2 to 6.4), ZG (1.9 days, 95% CI 0.4 to 3.5) had a significant lower overall mean days of sickness absence during last sick leave period (-2.9 days, 95% CI -5.1 to -0.7, p = 0.011) which corresponded to a moderate effect size (d = 0.60). Between baseline (88.5%, 95% CI 84.3 to 92.6) and 12 weeks (93.8%, 95% CI 89.4 to 98.2), ZG showed significant within-group improvement in total score of the Work Role Functioning Questionnaire (WRFQ) (5.3%, 95% CI 0.6 to 10.1, p = 0.029), corresponding to a moderate effect size (d = 0.40). This study indicates that two to three 1-hour weekly Zumba sessions can have a preventive effect on sick leave in female hospital employees.Highlights Participants in Zumba exercise organized by the workplace showed a significant lower number of sick leave days compared with the controlsDespite a correspondingly significant reduction in exercise adherence in both groups in the last 28 weeks, only FG showed tendencies for group improvement in job satisfaction and total WRFQ in this periodWorkplace promotion of exercise and physical activity can thus be beneficial for both the workers and the organization.



#5 Relationships between Internal Training Intensity and Well-Being Changes in Youth Football Players

Reference: Healthcare (Basel). 2022 Sep 21;10(10):1814. doi: 10.3390/healthcare10101814.

Authors: Rui Miguel Silva, Filipe Manuel Clemente, Francisco Tomás González-Fernández, Hadi Nobari, Rafael Oliveira, Ana Filipa Silva, José María Cancela-Carral

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Summary: The aim of this study was two-fold: (i) to analyze the variations of training intensity and well-being measures of youth football player over a 38 week period; and (ii) to test the relationships between training intensity and well-being variations throughout a youth football season. This study followed a longitudinal design, lasting 38 weeks. Twenty-five players (age: 15.0 ± 0.4 years) participated in this study. Participants were monitored daily to quantify the training intensity (TI) using the session-rate of perceived exertion (s-RPE) and its related indices: training monotony (TM), weekly training intensity (wTI), mean training intensity (mTI), and 5-day average (5d-AVG). A four-item questionnaire was collected daily to quantify the well-being status of each player. Fatigue, stress, delayed onset muscle soreness (DOMS), sleep quality, and the Hooper Index (HI) measures were analyzed. Kruskal-Wallis H test revealed significant differences for TM, mTI, wTI and 5d-AVG (H = 359.53, p = 0.001, η2 = 0.35; H = 414.97, p = 0.001, η2 = 0.41, H = 258.42, p = 0.001, η2 = 0.24 and H = 282.18, p = 0.001, η2 = 0.26). A positive large correlation was found between TM and sleep quality (r = 0.65, p = 0.05) and a negative large correlation between mTI and sleep quality (r = -0.69, p = 0.04). In conclusion, both TI and well-being measures present significant between-week differences at different periods of the season. Also, the variations of sleep quality seem to depend on TM and mTI variations across a youth football season.



#6 Sport-Specific Rehabilitation, but Not PRP Injections, Might Reduce the Re-Injury Rate of Muscle Injuries in Professional Soccer Players: A Retrospective Cohort Study

Reference: J Funct Morphol Kinesiol. 2022 Sep 21;7(4):72. doi: 10.3390/jfmk7040072.

Authors: Eduard Bezuglov, Vladimir Khaitin, Maria Shoshorina, Mikhail Butovskiy, Nikita Karlitskiy, Evgeny Mashkovskiy, Evgenii Goncharov, Bekzhan Pirmakhanov, Ryland Morgans, Artemii Lazarev

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Summary: Platelet-rich plasma (PRP) injections are extremely popular in the management of sports injuries in elite athletes. However, data on the use of various administration protocols of PRP are contradictory. The efficacy of platelet-rich plasma in the treatment of muscle injuries in professional soccer players has to be contextualized within the sport-specific rehabilitation program. Despite the questionable role of PRP, a well-structured rehabilitation program is still regarded as the gold standard. We examined the efficacy of various PRP protocols in the management of muscle injuries in professional soccer players in respect to treatment duration and injury recurrence. A retrospective cohort study. Muscle injuries in professional soccer players (n = 79, height 182.1 ± 5.9 cm, weight 76.8 ± 5.8 kg, BMI 23.1 ± 1.4 kg/m2) from three elite soccer clubs from the Russian Premier League were recorded during the 2018-2019 season. The injuries were graded based on MRI, using the British Athletic Muscle Injury Classification. Treatment protocols included the POLICE regimen, short courses of NSAID administration, and the specific rehabilitation program. The sample group of players were administered PRP injections. The average treatment duration with PRP injection was significantly longer than conventional treatment without PRP, 21.5 ± 15.7 days and 15.3 ± 11.1 days, respectively (p = 0.003). Soccer-specific rehabilitation and obtaining MRI/US before the treatment was associated with significantly reduced injury recurrence rate (p &lt; 0.001). There was no significant difference between the PRP injection protocol applied to any muscle and the treatment duration in respect of grade 2A-2B muscle injuries. The total duration of treatment of type 2A-2B injuries was 15 days among all players. In the group receiving local injections of PRP, the total duration of treatment was 18 days; in the group without PRP injections, the treatment duration was 14 days. In our study, PRP treatment was associated with longer treatment duration, regardless of which muscle was injured. This may reflect the tendency to use PRP in higher-degree injuries. Soccer-specific rehabilitation significantly reduced the injury recurrence rate when compared to the administration of PRP injections. MRI/US imaging before returning to play was also associated with a lower injury recurrence rate. There was no significant difference between the PRP injection protocol applied to any muscle and the treatment duration in treatment of type 2A-2B muscle injuries.



#7 A Multidisciplinary Investigation into the Talent Development Processes at an English Football Academy: A Machine Learning Approach

Reference: Sports (Basel). 2022 Oct 19;10(10):159. doi: 10.3390/sports10100159.

Authors: Adam L Kelly, Craig A Williams, Rob Cook, Sergio Lorenzo Jiménez Sáiz, Mark R Wilson

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Summary: The talent development processes in youth football are both complex and multidimensional. The purpose of this two-fold study was to apply a multidisciplinary, machine learning approach to examine: (a) the developmental characteristics of under-9 to under-16 academy players (n = 98; Study 1), and (b) the characteristics of selected and deselected under-18 academy players (n = 18; Study 2). A combined total of 53 factors cumulated from eight data collection methods across two seasons were analysed. A cross-validated Lasso regression was implemented, using the glmnet package in R, to analyse the factors that contributed to: (a) player review ratings (Study 1), and (b) achieving a professional contract (Study 2). Results showed non-zero coefficients for improvement in subjective performance in 15 out of the 53 analysed features, with key findings revealing advanced percentage of predicted adult height (0.196), greater lob pass (0.160) and average dribble completion percentage (0.124), more total match-play hours (0.145), and an older relative age (BQ1 vs. BQ2: -0.133; BQ1 vs. BQ4: -0.060) were the most important features that contributed towards player review ratings. Moreover, PCDEQ Factor 3 and an ability to organise and engage in quality practice (PCDEQ Factor 4) were important contributing factors towards achieving a professional contract. Overall, it appears the key factors associated with positive developmental outcomes are not always technical and tactical in nature, where coaches often have their expertise. Indeed, the relative importance of these factors is likely to change over time, and with age, although psychological attributes appear to be key to reaching potential across the academy journey. The methodological techniques used here also serve as an impetus for researchers to adopt a machine learning approach when analysing multidimensional databases.



#8 Assessment of Vaccination Status in Professional Football Players in Low Categories in Greece

Reference: J Funct Morphol Kinesiol. 2022 Sep 26;7(4):73. doi: 10.3390/jfmk7040073.

Authors: Dimitrios Papagiannis, Georgios Marinos, Ioannis Anyfantis, Georgios Rachiotis

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Summary: There are limited data on the vaccination practices of footballers in low professional categories in Greece and Europe. The aim of this study was to investigate the vaccination practices followed by the medical staff of the low professional football categories in Central Greece. A questionnaire was developed and included questions on the vaccination practices of football players. The participants were chief medical officers of the fifteen low-category football teams in Central Greece. Overall, 10 out of 15 chief medical officers participated (response rate: 67%). All participants recommended only the tetanus monovalent vaccine in cases with deep trauma of athletes. Influenza, pneumococcal vaccine, and Hepatitis A and B vaccines were not recommended by the medical officers. This was also the case for measles, mumps, rubella (MMR) vaccine and meningococcal vaccine with strains A, C, Y, W. Participants reported the lack of specific guidelines for vaccination in professional footballers. The recent study showed poor vaccination practices in low categories of professional football teams in Central Greece. The qualitative view of the respondents revealed the importance of the absence of guidelines on vaccination of football players.



#9 Chinese physical fitness standard for campus football players: A pilot study of 765 children aged 9 to 11

Reference: Front Physiol. 2022 Oct 5;13:1023910. doi: 10.3389/fphys.2022.1023910. eCollection 2022.

Authors: Hong Jia, Bin Wan, Te Bu, Yang Luo, Weiping Ma, Sen Huang, Liang Gang, Wei Deng, Zeyong Liu

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Summary: In 2022, 55 million Chinese children participate in campus football; however, there is no physical fitness standard, making it a priority task to enhance the current national program. This study aimed to explore a pilot method for the development of a reliable physical fitness standard. This study examined 765 male football players aged 9 to 11 in 2020 and 2022. The anthropometric and physical fitness assessments were conducted in accordance with the Chinese Football Association's field manuel. Physical fitness tests include sit and reach test, t test, 30 m run test, and vertical jump test. Physical fitness standard was modeled using the generalized additive models for location, scale, and shape (GAMLSS). Data were fitted with appropriate GAMLSS distributions and smoothing term. P-splines were applied to smooth the model's parameters using the default local maximum likelihood method and link functions. Following diagnostics of fitted models, age-specific centile estimations were computed for physical fitness tests. In addition, players in each age group were categorized according to their body mass index as normal weight or overweight/obese. Welch's t-test was utilized to compare the group differences in physical fitness testing. The significance level was chosen at p < 0.05. Sit and reach test, t test, 30 m run test, and vertical jump test data were fitted with original Sinh-Arcsinh, Box-Cox power exponential, Box-Cox power exponential, and Box-Cox Cole and Green, respectively. Physical fitness standard for each age group is presented as tabulated centiles (1p, 3p, 5p, 15p, 25p, 50p, 75p, 85p, 95p, 97p, 99p). Overweight/obese campus football players did significantly worse (p < 0.05) on the t test, 30 m run test, and vertical jump test than their normal-weight peers of the same age. This study developed the first physical fitness standard for 9 to 11-year-old campus football players in China. We made three recommendations to Chinese policymakers on sample size, data management, and field procedure for the creation of a national physical fitness standard.



#10 Non-steroidal anti-inflammatory drugs in football - a "Keeping SCORE" approach to judicious use

Reference: Sci Med Footb. 2022 Oct 28;1-5. doi: 10.1080/24733938.2022.2140189. Online ahead of print.

Authors: Craig Rosenbloom, Katrine Okholm Kryger, Sean Carmody, Daniel Broman

Summary: Non-steroidal anti-inflammatory drug (NSAID) use in elite sport is high, with football being no exception. Increased awareness of significant adverse drug reactions from published research and retired players commentary in the media have made the topic mainstream. Despite this increased awareness, usage rates show no sign of significantly reducing. Footballers, like all elite athletes are focused on maximising their performance and potential - even at the expense of their long-term health. An educational intervention prior to the 2010 FIFA Men's World Cup aimed at reducing rates was ineffective, suggesting that education alone is not the answer. Our author group propose a 'safer use' rather than 'no use' of NSAIDs in football. A 'Keeping SCORE' approach is suggested, designed as a prescribing aid. The approach guides medical staff towards focusing on Safety checks, Clinical indication/judgement, Open dialogue, Recording, and Evaluation.



#11 'If I am playing football, I forget that I have this virus': the challenges and coping strategies of adolescents with perinatally acquired HIV in KwaZulu-Natal, South Africa

Reference: BMC Infect Dis. 2022 Oct 21;22(1):796. doi: 10.1186/s12879-022-07780-x.

Authors: Marian Loveday, Jennifer Furin, Sindisiwe Hlangu, Thabile Mthethwa, Tasneem Naidoo

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Summary: Adolescents who have acquired HIV perinatally (ALHIV) face unique challenges in taking lifelong antiretroviral therapy (ART), but little is known about what factors affect their adherence over the course of their lifelong treatment journey. We conducted a qualitative study with ALHIV who had periods of poor adherence to ART in KwaZulu-Natal, South Africa using Participant-generated Visual Methodologies (PVM). Participants used photography to represent their perspectives and experiences. 14 individuals participated in the research process. We developed a framework and identified four social domains which combined with the adolescent's own experiences and sense of self to either support or undermine adherence. Periods of non-adherence were reported by all participants. Participants described the importance of supportive relationships and households as well as the benefits of ART as supporting adherence. The fear of inadvertent disclosure of their HIV status and the side-effects of ART were barriers to adherence. Possible interventions to support adolescents in their treatment journey are identified. Current models of adherence support fail to address the challenges to lifelong therapy ALHIV face. Ongoing education and honest communication with health care providers, interventions that build resilience together with peer support, have the potential to improve adherence in ALHIV.



#12 Effect of the Length of the Microcycle on the Daily External Load, Fatigue, Sleep Quality, Stress, and Muscle Soreness of Professional Soccer Players: A Full-Season Study

Reference: Sports Health. 2022 Oct 30;19417381221131531. doi: 10.1177/19417381221131531.

Authors: José M Oliva Lozano, José M Muyor, Andrés Pérez-Guerra, David Gómez, Jorge Garcia-Unanue, Javier Sanchez-Sanchez, José Luis Felipe

Summary: The aim of this study was to analyze the effect of the length of the microcycle (ie, training period from the day after the match to the following match) on the daily external load and perceived wellness of professional soccer players (Spanish LaLiga Smartbank). We hypothesized that the length of the microcycle has a significant effect on the daily external load and perceived wellness. Data were collected daily during a full season using perceived wellness questionnaires and electronic performance and tracking systems. The length of the microcycle had a significant effect on volume- and intensity-related external load variables. There were differences between short, regular, and long microcycles depending on the day of the microcycle. These differences were observed in all external load variables. However, no significant differences between short, regular, or long microcycles were found on match day for any external load variable, except for high-intensity decelerations. Regarding the perceived wellness, the length of the microcycle had no effect on these variables, and there were no significant interactions between the length and the day of the microcycle. The length of the microcycle had a significant effect on volume- and intensity-related external load variables, but no significant effect on perceived wellness was observed. These data may help strength and conditioning coaches understand that workload periodization should take this contextual variable into account, especially for external training load. In addition, this study may serve as a guide for practitioners to know the physical requirements of professional soccer players in Spanish LaLiga Smartbank, because the weekly external load profile and perceived wellness have been reported for different lengths of the microcycles. Thus, these data may be used for player load management.



#13 Decrease in aerial challenges after revision of goal kick rules in Japan Professional Soccer League: explorative study of the possibility of a risk reduction for head injury, concussion, and brain damage by a rule revision

Reference: Sci Med Footb. 2022 Nov 3;1-6. doi: 10.1080/24733938.2022.2142274. Online ahead of print.

Authors: Kenichi Shibukawa, Yoshihiro Hoshikawa

Summary: In 2019, FIFA revised the goal kick (GLK) rule such that a GLK could be performed even if the kicker had teammates in the penalty area. This study aimed to examine whether the rule revision reduced the frequency of aerial challenge (AC) and long GLKs (LGLKs), which are risk factors for head injury and concussion in soccer. We analyzed all official league matches (306 matches/season) of the Japan Professional Soccer League 1st Division before (2018 season) and after the rule revision (2020 season). The analysis categorized GLKs into short GLKs (SGLKs) and LGLKs, depending on the GLK distance, and included the frequency and causes of AC, in each match following a GLK, which were compared between the 2018 and 2020 seasons. The average number of LGLKs per match in the 2020 season (8.85) decreased compared to that in the 2018 season (14.20). Additionally, for ACs following a GLK, the frequency of ACs decreased from 6.08 to 3.92 per match. Meanwhile, the frequency of LGLKs tended to increase toward the end of the first and second halves in matches. The results of this study revealed that the 2019 GLK rule revision reduced the number of LGLKs and ACs.



#14 No Association Between Processing Speed and Risk of Sport-Related Concussion in Youth Soccer

Reference: Clin J Sport Med. 2022 Nov 1;32(6):e587-e590. doi: 10.1097/JSM.0000000000001064.

Authors: Ruby Lopez-Flores, Jessie Oldham, David Howell, Justin Rush, Alex Taylor, Paul Berkner, Rebekah Mannix, William P Meehan 3rd

Summary: The aim was to determine whether slow processing speed is associated with risk of sport-related concussion. We conducted a retrospective cohort study using computerized neurocognitive assessments (Immediate Post-concussion Assessment and Cognitive Testing [ImPACT]) from the Massachusetts Concussion Management Coalition. Slow processing speed was defined as 2 SD below the sample mean (n = 131) and fast processing speed as 2 SD above the sample mean (n = 259). We used a binary logistic regression model to determine the odds of sustaining a concussion with our main predictor being processing speed (high or low) adjusted for the effects of age, sex, and prior number of concussions. Three hundred ninety junior high soccer players ages 10 to 15 with a baseline score for ImPACT. Risk of sustaining a concussion was used as the outcome variable. Those with slow processing speed had a visual motor composite score of ≤19.92, those with fast-processing speed had a score of ≥46.20. Athletes with slow processing speed were younger (13 vs 14 years; P < 0.001) and more likely to be male (57% vs 49%; P = 0.014). After adjusting for the effects of age, sex, and prior concussions, there was no significant difference in the odds of sustaining a concussion between groups (aOR 1.01; 95% CI, 0.99-1.04). Despite previous research showing that slow processing speed is a risk factor for musculoskeletal injuries during sports, our study suggests that processing speed is not associated with the risk of sustaining a concussion among junior high school soccer players.



#15 Determining the hip joint isokinetic muscle strength and range of motion of professional soccer players based on their field position

Reference: PeerJ. 2022 Oct 26;10:e14000. doi: 10.7717/peerj.14000. eCollection 2022.

Authors: Ali AlTaweel, Shibili Nuhmani, Mohammad Ahsan, Turki Abualait, Qassim Muaidi

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Summary: Soccer players' physical and physiological demands vary based on their field position. Although the hip joint has an important role in soccer, little information is available about the strength and flexibility of the hip joint based on player positions. Therefore, this study aims to investigate the differences in muscle strength and flexibility of the hip joint of professional soccer players based on their field position. Ninety-six professional soccer players from Saudi Arabia were divided into four groups (goalkeepers, defenders, midfielders, and attackers), with 24 participants in each group based on their field position. The Modified Thomas test was used to measure the hip extension range of motion (ROM), and muscle strength was assessed by an Isokinetic dynamometer. There were no statistically significant differences in the isokinetic strength at the hip joint movements between goalkeepers, defenders, midfielders, and attackers (p ≥ 0.05). At the same time, there was a significant difference between groups in the hip extension ROM (p ≤ 0.05). according to different player positions. Post hoc tests reported significant differences between goalkeepers and defenders (p ≤ 0.05), midfielders (p ≤ 0.05), and attackers p ≤ 0.05). At the same time, there were no significant differences between defenders and midfielders (p ≥ 0.05), defenders and attackers (p ≥ 0.05), and midfielders and attackers (p ≥ 0.05). Even though there was no significant difference in isokinetic strength, there was a significant difference in hip extension ROM among players based on field position. This study may help coaches and trainers to recognize the strengths and weaknesses of players and design training programs to rectify the weaker components and improve players' performance in different playing positions.






Clustering ball possession duration according to players’ role in football small-sided games

This study aimed to explore which offensive variables best discriminate the ball possession duration according to players specific role (defenders, midfielders, attackers) during a 3vs3+Gk football small-sided games (SSG).





Workload is associated with the occurrence of non-contact injuries in professional male footballers

This cohort study describes the relationship between workload parameters and the occurrence of non-contact injuries, during weeks with high and low workload in professional soccer players throughout the season.





Latest research in football - week 41 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 What Does Provide Better Effects on Balance, Strength, and Lower Extremity Muscle Function in Professional Male Soccer Players with Chronic Ankle Instability? Hopping or a Balance Plus Strength Intervention? A Randomized Control Study

Reference: Healthcare (Basel). 2022 Sep 21;10(10):1822. doi: 10.3390/healthcare10101822.

Authors: Hadi Mohammadi Nia Samakosh, João Paulo Brito, Seyed Sadredin Shojaedin, Malihe Hadadnezhad, Rafael Oliveira

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Summary: Chronic ankle instability (CAI) has a higher frequency in soccer due to the rapid changes in body movement. Thus, this study compared the effects of eight weeks of a hopping protocol and a combined protocol of balance plus strength in a within-between group analysis. Thirty-six male professional soccer players participated in this study and were randomly allocated in three groups: control group (CG, n = 12), hopping group (HG, n = 12), and balance plus strength group (BSG, n = 12). Strength, static and dynamic balance, and function were assessed at baseline and eight weeks post intervention. First, Foot and Ankle Ability Measure (FAAM) and FAAM sport scales were applied. Then, a dynamometer was used to measure strength of the muscles around the hip, knee, and ankle joints. The Bass stick measured static balance and the Y balance test measured dynamic balance. Additionally, functional tests were carried out by Triple Hop, the Figure 8 hop, and vertical jump. A repeated measures ANOVA [(3 groups) × 2 moments] was used to compare the within and between group differences. In general, all tests improved after eight weeks of training with both protocols. Specifically, the BSG improved with large ES for all tests, while the HG improved all test with small to large effect sizes (ES). Furthermore, HG showed higher values for vertical jump (p &lt; 0.01, ES = 1.88) and FAAMSPORT (p &lt; 0.05, ES = 0.15) than BSG. BSG showed higher values for hip abduction (p &lt; 0.05, ES = 2.77), hip adduction (p &lt; 0.05, ES = 0.87), and ankle inversion (p &lt; 0.001, ES = 1.50) strength tests, while HG showed higher values for knee flexion [ES = 0.86, (0.02, 1.69)] and ankle plantarflexion [ES = 0.52, (-0.29, 1.33)]. Balance plus strength protocol showed more positive effects than the hopping protocol alone for soccer players with CAI.



#2 Muscle and Tendon Stiffness of the Lower Limb of Professional Adolescent Soccer Athletes Measured Using Shear Wave Elastography

Reference: Diagnostics (Basel). 2022 Oct 11;12(10):2453. doi: 10.3390/diagnostics12102453.

Authors: Claudia Römer, Julia Czupajllo, Enrico Zessin, Thomas Fischer, Bernd Wolfarth, Markus Herbert Lerchbaumer

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Summary: While adolescents have specific risk factors for acute and chronic injury, there is a lack of preventive medicine algorithms for this vulnerable group. Shear wave elastography (SWE) is currently mainly used for assessing muscle and tendon stiffness in adult athletes and can diagnose tissue pathologies such as tendinopathy. The aim was to investigate differences in quadriceps tendon and muscle stiffness between adolescent and adult professional soccer players using SWE and identify lateral imbalances in order to improve the knowledge of preventive medicine algorithms for professional adolescent athletes. Standardized SWE examinations of both lower limb tendons and muscles (the quadriceps tendon (QT) and the vastus medialis (VM) muscle) in the longitudinal plane and relaxed tendon position were performed in 13 healthy adolescent soccer athletes (13-17 years), and a control group of 19 healthy adult professional soccer athletes (18-29 years). Adolescent soccer players had lower stiffness values for both the quadriceps tendon (3.11 m/s vs. 3.25 m/s) and the vastus medialis muscle (1.67 m/s vs. 1.71 m/s) than adult athletes. Moreover, QT stiffness in adolescent soccer players was significantly lower on the right side (QT: adult 3.50 m/s (2.73-4.56) vs. adolescent 2.90 m/s (2.61-3.12); p = 0.031). Analysis of the lateral differences revealed softer QT and VM tissue on the right side in over two-thirds of adolescent soccer athletes. Over two-thirds of adults had stiffer QT and VM tissue on the right side. In adolescent soccer players, the stiffness of the QT and VM muscle measured by SWE is lower in the right leg. SWE of the musculoskeletal system may thus become a relevant diagnostic tool to detect early lateral imbalances as a main risk factor for injury and may thus contribute to the prevention of acute and chronic injury prevention in adolescent athletes.



#3 From Junior to Elite in Soccer: Exploring the Relative Age Effect and Talent Selection in Spanish Youth National Teams

Reference: Children (Basel). 2022 Oct 10;9(10):1543. doi: 10.3390/children9101543.

Authors: Javier García-Rubio, Andrés García-Vallejo, María de Los Ángeles Arenas-Pareja, Pablo López-Sierra, Sergio J Ibáñez

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Summary: The implications of relative age grouping in sport are known as the Relative Age Effect (RAE). This study has the twofold purpose of analyzing RAE in Spanish youth national soccer teams and examining the prediction value of being selected for national youth teams to be a professional. The sample was composed of 548 players divided into five groups. A descriptive analysis of distribution and participation, frequencies, mean and standard deviation, crosstabs, Sankey charts, coefficient correlation and Cohen's effect size criteria and two regression analyses were performed. Results established that the RAE is present in U'17 to U'21 Spanish youth national teams. Talent detection and selection programs are more reliable the closer they are to adulthood, reaching a success rate of almost 100% at the U'21 stage. The selection of players for such programs should be delayed as much as possible, thus, preventing younger players from dropping out and those selected from thinking they have already reached their goal. To this end, they should focus on long-term improvement, not short-term performance. In addition, factors such as the RAE or the maturity level of the athletes should be monitored.



#4 Predictive Value of Repeated Jump Testing on Nomination Status in Professional and under 19 Soccer Players

Reference: Int J Environ Res Public Health. 2022 Oct 11;19(20):13077. doi: 10.3390/ijerph192013077.

Authors: Zacharias Papadakis, Vassilios Panoutsakopoulos, Iraklis A Kollias

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Summary: Soccer clubs invest time and money in multidimensional identification practices, but the field implementation is still problematic. The repeated vertical jump test (RVJ), as an alternative to the monodimensional vertical jump, may offer similar prognostic value. Therefore, the prognostic validity of 15 RVJ within professional (PRO, n = 24) and under 19 years old (U19, n = 20) Greek male soccer players was examined. T-test, binomial logistic regression, and receiver operating characteristic for prognostic validity of anthropometric and performance values in predicting PRO status were applied using Jamovi version Significant group differences presented in body height and mass, body mass index (BMI), maximum and average jump height, and relative jump power. The predicting model was significant (x2(2) = 17.12, p &lt; 0.001). Height and BMI were positive predictors of the PRO status (b = 21.66, p = 0.008 and b = 0.94, p = 0.014, respectively). The model was 73% accurate, 75% specific, and 71% sensitive, with excellent area under the curve. The RVJ test demonstrated outstanding discriminating prognostic validity. Until the applicability of the multidimensional models in predicting future player status is further established, field practitioners may use the simplistic RVJ testing to predict future status among male soccer players.



#5 The Effect of FIFA 11+ on the Isometric Strength and Running Ability of Young Soccer Players

Reference: Int J Environ Res Public Health. 2022 Oct 13;19(20):13186. doi: 10.3390/ijerph192013186.

Authors: Xin Zhou, Anmin Luo, Yifei Wang, Qingqing Zhang, Yu Zha, Sicheng Wang, Caroline Ashton, John Ethan Andamasaris, Henry Wang, Qirong Wang

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Summary: Soccer is the world's game, and keeping athletes healthy while playing the game has often been a focus of study. There is a high occurrence of musculoskeletal injuries reported in soccer. FIFA 11+ was developed as an intervention to help prevent such injuries. FIFA 11+ has previously been studied for its efficacy as an injury prevention program, but not for its effect on sports performance in an adolescent population. The purpose of this study was to look at the effect of implementing the FIFA 11+ intervention on strength, speed, and agility. Twenty youth soccer players were randomly divided into an intervention group (INT) and a control group (CON). The intervention lasted for eight weeks and performance assessments were completed pre- and post-intervention. Post-test INT knee flexor strength was significantly higher than pre-test scores (p &lt; 0.05). INT also demonstrated significantly higher hamstring to quadriceps strength ratio (H/Q) after the intervention (p &lt; 0.05), while the CON H/Q did not change significantly. 30-m sprint performance of both groups improved from pre- to post-test (p &lt; 0.05). Shuttle run performance was significantly improved in post-test scores for INT players (p &lt; 0.05), but did not change significantly for the CON players. It is suggested that implementing FIFA 11+ before training in young soccer players can lead to performance benefits as well as injury prevention benefits.



#6 A Systematic Review of the Relationship between Workload and Injury Risk of Professional Male Soccer Players

Reference: Int J Environ Res Public Health. 2022 Oct 14;19(20):13237. doi: 10.3390/ijerph192013237.

Authors: Zhiyuan Jiang, Yuerong Hao, Naijing Jin, Yue Li

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Summary: The number of studies on the relationship between training and competition load and injury has increased exponentially in recent years, and it is also widely studied by researchers in the field of professional soccer. In order to provide practical guidance for workload management and injury prevention in professional athletes, this study provides a review of the literature on the effect of load on injury risk, injury prediction, and interpretation mechanisms. The results of the research show that: (1) It appears that short-term fixture congestion may increase the match injury incidence, while long-term fixture congestion may have no effect on both the overall injury incidence and the match injury incidence. (2) It is impossible to determine conclusively whether any global positioning system (GPS)-derived metrics (total distance, high-speed running distance, and acceleration) are associated with an increased risk of injury. (3) The acute:chronic workload ratio (ACWR) of the session rating of perceived exertion (s-RPE) may be significantly associated with the risk of non-contact injuries, but an ACWR threshold with a minimum risk of injury could not be obtained. (4) Based on the workload and fatigue recovery factors, artificial intelligence technology may possess good predictive power regarding injury risk.



#7 The Effect of 12-Weeks Recreational Football (Soccer) for Health Intervention on Functional Movement in Older Adults

Reference: Int J Environ Res Public Health. 2022 Oct 20;19(20):13625. doi: 10.3390/ijerph192013625.

Authors: Michael J Duncan, Sophie Mowle, Mark Noon, Emma Eyre, Neil D Clarke, Mathew Hill, Jason Tallis, Mikko Julin

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Summary: There is growing evidence that recreational football offers health benefits for older adults and an important pathway for physical activity for older adult groups. Despite anecdotal evidence that recreational football is beneficial for older adults, no empirical data are available to support this assertion. This study addressed this issue and examined the effects of a 12-week recreational football intervention on the functional fitness of older adults. Using a pre-post case-control design, thirteen males, aged 61-73 years (mean age ± SD = 66 ± 4 years) undertook a twice-weekly, 12-week recreational football for health intervention, and were matched with a control group, comprising thirteen males, aged 62-78 years (mean age ± SD = 66 ± 4 years) who maintained their typical exercise habits during the intervention period. Pre- and postintervention, participants underwent assessment of functional fitness, using the Rikli and Jones functional fitness battery as well as an assessment of body fatness, via bioelectrical impedance analysis and dominant handgrip strength using handgrip dynamometry. Results from a series of 2 (pre-post) X 2 (intervention vs. control) repeated-measures ANOVAs indicate significant pre-post X group interactions for the 30-second chair stand (p = 0.038, Pƞ2 = 0.168), 8-foot timed up and go (p = 0.001, Pƞ2 = 0.577) and 6 min walk test (p = 0.036, Pƞ2 = 0.171). In all cases, performance improved significantly after the intervention for the football intervention group but not the control group. There were no significant differences in the 30 s arm curl test or dominant handgrip strength (p &gt; 0.05). There was a non-significant trend (p = 0.07, Pƞ2 = 0.127) towards a pre-post X group interaction for body fatness, showing a decreased percent body fat for the intervention group over the control group. The results of the present study demonstrate the utility of recreational football as a physical activity intervention in older adults to improve functional movement.



#8 Ketone Ester Supplementation Improves Some Aspects of Cognitive Function during a Simulated Soccer Match after Induced Mental Fatigue

Reference: Nutrients. 2022 Oct 19;14(20):4376. doi: 10.3390/nu14204376.

Authors: Manuel D Quinones, Peter W R Lemon

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Summary: Ketone supplementation has been proposed to enhance cognition during exercise. To assess whether any benefits are due to reduced cognitive fatigue during the latter portions of typical sport game action, we induced cognitive fatigue, provided a ketone monoester supplement (KME) vs. a non-caloric placebo (PLAC), and assessed cognitive performance during a simulated soccer match (SSM). In a double-blind, balanced, crossover design, nine recreationally active men (174.3 ± 4.2 cm, 76.6 ± 7.4 kg, 30 ± 3 y, 14.2 ± 5.5 % body fat, V˙O2 max = 55 ± 5 mL·kg BM-1·min-1; mean ± SD) completed a 45-min SSM (3 blocks of intermittent, variable intensity exercise) consuming either KME (25 g) or PLAC, after a 40-min mental fatiguing task. Cognitive function (Stroop and Choice Reaction Task [CRT]) and blood metabolites were measured throughout the match. KME reduced concentrations of both blood glucose (block 2: 4.6 vs. 5.2 mM, p = 0.02; block 3: 4.7 vs. 5.3 mM, p = 0.01) and blood lactate (block 1: 4.7 vs. 5.4 mM, p = 0.05; block 2: 4.9 vs. 5.9 mM, p = 0.01) during the SSM vs. PLAC, perhaps indicating a CHO sparing effect. Both treatments resulted in impaired CRT performance during the SSM relative to baseline, but KME displayed a reduced (p &lt; 0.05) performance decrease compared to PLAC (1.3 vs. 3.4% reduction in correct answers, p = 0.02). No other differences in cognitive function were seen. These data suggest that KME supplementation attenuated decrements in CRT during repeated, high intensity, intermittent exercise. More study is warranted to assess fully the potential cognitive/physical benefits of KME for athletes.



#9 The levels of TGFβ1, VEGF, PDGF-BB, and PF4 in platelet-rich plasma of professional soccer players: a cross-sectional pilot study

Reference: J Orthop Surg Res. 2022 Oct 27;17(1):465. doi: 10.1186/s13018-022-03362-4.

Authors: Tomoharu Mochizuki, Takashi Ushiki, Satoshi Watanabe, Go Omori, Tomoyuki Kawase

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Summary: Regenerative therapy using platelet-rich plasma (PRP), a rich source of growth factors, has become popular in orthopedic sports medicine. Elite athletes prefer PRP therapy for their injured muscles and tendons primarily to avoid the possible risks of surgical treatment. However, the clinical effectiveness of PRP therapy in elite athletes compared to that in non-athletes remains unknown. Therefore, to investigate the effectiveness of PRP therapy in professional athletes (pro-athletes), we focused on the quality of PRP preparations and compared the levels of bioactive molecules between pro-athletes and non-athletes. PRP was prepared from healthy, non-smoking male professional soccer players (pro-athletes) (n = 22) and non-athletes (VEGF: n = 34, others: n = 38). The levels of TGFβ1, PDGF-BB, VEGF, and PF4 were determined using ELISA kits. Polyphosphate was probed with 4',6-diamidino-2-phenylindole and monitored using a fluorometer. The body composition of the donors was determined using a bathroom weighing scale. The levels of TGFβ1 and VEGF were significantly lower in pro-athletes than in non-athletes, whereas PF4 levels were significantly higher in pro-athletes. No significant difference was found in PDGF-BB levels between these groups. Biomolecule levels were not correlated with polyphosphate levels. TGFβ1, VEGF, and PDGF-BB levels in pro-athletes were not higher than those in non-athletes. These findings suggest that growth factor levels in PRP may not be a predominant determinant of the clinical effectiveness of PRP therapy in pro-athletes. Increased PF4 levels in pro-athletes suggest an immunological function of PRP that may positively influence tissue regeneration.



#10 Overestimation of maximal aerobic speed by the Université de Montréal track test and a 1500-m-time trial in soccer

Reference: Front Physiol. 2022 Oct 11;13:1023257. doi: 10.3389/fphys.2022.1023257. eCollection 2022.

Authors: Maximiliane Thron, Alexander Woll, Leon Klos, Sascha Härtel, Ludwig Ruf, Christian Kloss, Stefan Altmann

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Summary: Maximal aerobic speed (MAS), usually measured by cardiopulmonary exercise testing (CPET) on a treadmill, is gaining popularity in soccer to determine aerobic performance. Several field tests are used to estimate MAS, although, gold standard methods are still not clarified. Therefore, this work aims 1) to compare two different CPET based methods to assess MAS and 2) to investigate the convergent validity of two common field tests to estimate MAS in soccer. Thirteen trained male soccer players completed an CPET on a treadmill to determine two VO2-kinetic based definitions of MAS (MASPlateau = speed at onset of VO2-plateau = gold standard; MAS30s = first speed of 30-s-interval of VO2max), the Université de Montreal Track Test (UMTT; VUMTT = speed of the last stage), and a 1500-m-time trial (1500-m-TT; V1500m = average speed). MASPlateau, MAS30s, VUMTT, and V1500m were compared using ANOVA. Additionally, limits of agreement analysis (LoA), Pearson's r, and ICC were calculated between tests. MAS30s, VUMTT, and V1500m significantly overestimated MASPlateau by 0.99 km/h (ES = 1.61; p < 0.01), 1.61 km/h (ES = 2.03; p < 0.01) and 1.68 km/h (ES = 1.77; p < 0.01), respectively, with large LoA (-0.21 ≤ LoA≤3.55), however with large-to-very large correlations (0.65 ≤ r ≤ 0.87; p ≤ 0.02; 0.51 ≤ ICC≤ 0.85; p ≤ 0.03). The overestimation and large LoA of MASPlateau by all estimates indicate that 1) a uniform definition of MAS is needed and 2) the UMTT and a 1500-m-TT seem questionable for estimating MAS for trained soccer players on an individual basis, while regression equations might be suitable on a team level. The results of the present work contribute to the clarification of acquisition of MAS in soccer.



#11 Innate immunity changes in soccer players after whole-body cryotherapy

Reference: BMC Sports Sci Med Rehabil. 2022 Oct 25;14(1):185. doi: 10.1186/s13102-022-00578-z.

Authors: Valentina Selleri, Marco Mattioli, Domenico Lo Tartaro, Annamaria Paolini, Giada Zanini, Anna De Gaetano, Roberta D'Alisera, Laura Roli, Alessandra Melegari, Pasqualino Maietta, Ferdinando Tripi, Emanuele Guerra, Johanna Chester, Gustavo Savino, Tommaso Trenti, Andrea Cossarizza, Anna Vittoria Mattioli, Marcello Pinti, Milena Nasi

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Summary: Whole-body cryotherapy (WBC) consists of short exposure (up to 2-3 min) to dry air at cryogenic temperatures (up to -190 °C) and has recently been applied for muscle recovery after injury to reduce the inflammation process. We aimed to determine the impact of cryotherapy on immunological, hormonal, and metabolic responses in non-professional soccer players (NPSPs). Nine male NPSPs (age: 20 ± 2 years) who trained regularly over 5 consecutive days, immediately before and after each training session, were subjected to WBC treatment (WBC-t). Blood samples were collected for the evaluation of fifty analytes including hematologic parameters, serum chemistry, and hormone profiles. Monocytes phenotyping (Mo) was performed and plasmatic markers, usually increased during inflammation [CCL2, IL-18, free mitochondrial (mt)DNA] or with anti-inflammatory effects (IL2RA, IL1RN), were quantified. After WBC-t, we observed reduced levels of ferritin, mean corpuscular hemoglobin, mean platelet volume, testosterone, and estradiol, which however remain within the normal ranges. The percentage of the total, intermediates and non-classical Mo increased, while classical Mo decreased. CXCR4 expression decreased in each Mo subset. Plasma IL18 and IL2RA levels decreased, while IL1RN only exhibited a tendency to decrease and CCL2 showed a tendency to increase. Circulating mtDNA levels were not altered following WBC-t. The differences observed in monocyte subsets after WBC-t may be attributable to their redistribution into the surrounding tissue. Moreover, the decrease of CXCR4 in Mo subpopulations could be coherent with their differentiation process. Thus, WBC through yet unknown mechanisms could promote their differentiation having a role in tissue repair.



#12 Biochemical and Physical Performance Responses to a Soccer Match after a 72-Hour Recovery Period

Reference: Sports (Basel). 2022 Sep 22;10(10):140. doi: 10.3390/sports10100140.

Authors: Diego Marqués-Jiménez, Julio Calleja-González, Iñaki Arratibel-Imaz, Nicolás Terrados

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Summary: The physiological and neuromuscular responses at 72 h post-match are not widely researched, despite evidence showing substantial changes in recovery markers at 72 h post-match. Consequently, the aim of this study was to determine the biochemical and physical performance responses to a soccer match after a 72-h recovery period. Male soccer players of a semiprofessional team participated in this study. Before playing a friendly match, blood values of testosterone, cortisol, the testosterone-to-cortisol ratio and urea were collected and the squat jump and the Bangsbo Repeated Sprint Ability test were performed. These measurements were considered as baseline (pre match) and were obtained again after a 72-h recovery period. Results indicate that physical performance at 72 h post-match was similar to baseline (squat jump: p = 0.974; total Repeated Sprint Ability time: p = 0.381; Repeated Sprint Ability fatigue index: p = 0.864). However, perturbations in the biochemical milieu derived from the soccer match metabolic and physiological stress were still evident at this time point. While no significant differences compared to pre match were obtained in testosterone and urea concentrations after the recovery period, cortisol and testosterone-to-cortisol ratio values were significantly higher (14.74 ± 3.68 µg/dL vs. 17.83 ± 2.65 µg/dL; p = 0.045; ES 0.92 [0.00; 1.84], very likely) and lower (39.08 ± 13.26 vs. 28.29 ± 7.45; p = 0.038; ES -0.96 [-1.89; -0.04], very likely), respectively. In conclusion, soccer players have similar physical performance to the pre match after a 72-h recovery period, even with signs of biochemical and physiological stress.



#13 Differences across Playing Levels for Match-Play Physical Demands in Women's Professional and Collegiate Soccer: A Narrative Review

Reference: Sports (Basel). 2022 Sep 22;10(10):141. doi: 10.3390/sports10100141.

Authors: Erin Choice, James Tufano, Kristen Jagger, Kayla Hooker, Kristen C Cochrane-Snyman

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Summary: Advancements in sport technology have made quantifying match-play external load (e.g., total distance, sprint distance, number of sprints) a popular option for athletics personnel. These variables of volume and intensity are useful for both objectively monitoring training in field-based sports and for designing training programs. As physical abilities differ across playing levels, match-play demands likely also differ. This narrative review compiles and compares the match-play external load data for women's soccer at the professional and collegiate levels. Databases were searched through July 2022, yielding 13 primary articles that assessed the match-play demands of women's soccer (3 professional, 8 Division I, 1 Division II, and 1 Division III). The results indicate that the average total distance covered were similar between the professional, Division I and Division III levels, but the variability was greater among Division III compared to professional and Division I players. Data for Division II are scarce, but the total distance covered appears to be less than for professional, Division I and Division III. There was also large variability for sprint distance and number of sprints across data at all playing levels. Considering the lack of studies of Division II and Division III players, more research is necessary to determine how playing level may affect external load profiles, as isolated studies likely only reflect data from isolated teams.



#14 The Physical Demands of Match-Play in Academy and Senior Soccer Players from the Scottish Premiership

Reference: Sports (Basel). 2022 Oct 8;10(10):150. doi: 10.3390/sports10100150.

Authors: Ryland Morgans, Eduard Bezuglov, Patrick Orme, Kyler Burns, Dave Rhodes, John Babraj, Rocco Di Michele, Rafael Franco Soares Oliveira

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Summary: The present study aimed to assess the physical match performance among senior and youth soccer players from an elite Scottish Premiership club during the 2021/2022 season. Twenty-two first team (25.9 ± 4.5 years, 78.3 ± 8.2 kg, 1.82 ± 0.07 cm) and 16 youth players (16.8 ± 0.9 years, 70.1 ± 6.8 kg, 177 ± 5.8 cm) were examined. A selection of physical match performance variables were measured using a global positioning system. Linear mixed-effect regressions revealed for all examined variables no significant differences between first team and U-18 players and no significant differences between playing level by position interaction. Across both teams, Centre Backs compared to Wing Backs, showed a 295 m (p &lt; 0.01) lower high-intensity distance, and performed on average 36 fewer very-high intensity decelerations (p = 0.03). Comparing to Wide Midfielders, Centre Backs showed lower total (1297 m, p = 0.01), high-intensity (350 m, p = 0.01), and sprint (167 m, p &lt; 0.01) distances. Sprint distance was also lower in Centre Backs vs. Strikers (118 m, p = 0.03), and in Central Midfielders vs. both Strikers (104 m, p = 0.03) and Wide Midfielders (154 m, p = 0.01). The present findings highlight the physical match performance of elite Scottish players and provide useful information within the context of understanding how methods of physical development of youth soccer are implemented in different countries.



#15 Cognitive and Behavioral Outcomes in Male and Female NCAA Soccer Athletes across Multiple Years: A CARE Consortium Study

Reference: Med Sci Sports Exerc. 2022 Oct 26. doi: 10.1249/MSS.0000000000003063. Online ahead of print.

Authors: Jaclyn B Caccese, Kelsey N Bryk, Tara Porfido, Abigail C Bretzin, Kerry Peek, Thomas W Kaminski, Anthony P Kontos, Sara P D Chrisman, Margot Putukian, Thomas A Buckley, Steven P Broglio, Thomas W McAllister, Michael A McCrea, Paul F Pasquina, Carrie Esopenko, CARE Consortium Investigators

Summary: The purpose of this study was to determine changes in neurocognitive, psychosocial, and balance functioning in collegiate male and female soccer players across three consecutive years of baseline testing compared to a control group of non-contact athletes. Generalized estimating equations were used to compare changes in annual, pre-season baseline measures of neurocognitive function, neurobehavioral and psychological symptoms, and postural stability between collegiate soccer players (n = 75; 51 [68%] female soccer players) and non-contact athletes (n = 210; 133 [63%] female non-contact athletes) across three consecutive years. Among all participants, the group-by-time interaction was not significant for any outcome measures. Overall, soccer players reported lower (better) Brief Symptom Inventory 18 Depression (p = 0.004, Exp(B) = 0.36 [95% CI 0.18-0.73]), Global Severity Index (p = 0.006, Exp(B) = 0.53 [95% CI 0.33-0.84]), and Post-Concussion Symptom Scale (PCSS) Symptom Severity (p < 0.001, Exp(B) = 0.45 [95% CI 0.22-0.95]) scores than non-contact athletes. No other outcome measures were different between soccer players and non-contact athletes. Among collegiate athletes, soccer players report similar or better psychosocial functioning and symptom scores than non-contact athletes. Importantly, neurocognitive functioning, neurobehavioral and psychological symptoms, and postural stability does not worsen over time in collegiate soccer players relative to their non-contact counterparts. Our findings suggest that despite possible exposure to repetitive head impacts (RHIs), collegiate soccer players do not exhibit changes in observable function and symptoms across multiple seasons.



#16 External Focus Reduces Accuracy and Increases Antagonist Muscle Activation in Novice Adolescent Soccer Players

Reference: Motor Control. 2022 Oct 26;1-14. doi: 10.1123/mc.2022-0018. Online ahead of print.

Authors: Serkan Uslu, Emel Çetin Özdoğan

Summary: Instep kick is one of the most effective kicking techniques in soccer. Lower extremity muscles and joints play a crucial role during instep kick. However, external (EF) and internal focus and their effect on the muscles are still ambiguous. In this study, 13 male adolescent soccer players were included and aimed to hit the targets in internal and EF conditions. Lower extremity muscle activations were measured with surface electromyography, and kinematics were measured with a high-speed video camera. Muscle activations and movement latencies were analyzed in four different phases (backswing, leg cocking, acceleration, and follow-through) of kicking. While 10 out of 13 participants kicked accurately in internal focus, only five out of 13 in EF kicked accurately. Gastrocnemius muscle activations increased significantly in EF in all phases except acceleration. Movement latencies were found 0.07 ± 0.002 s for accurate and 0.05 ± 0.004 s for inaccurate kicks in EF. A correlation has been found between accuracy and movement latency in EF (R = .67). Our results suggest that novices cannot yet coordinate their muscles in EF, cocontraction ratio increases. Therefore, training strategies that aim to reduce the cocontraction ratio can help the athlete increase performance through better motor coordination. Moreover, better motor coordination may be beneficial in preventing injuries (joint stiffness, etc.) caused by increased cocontraction ratio.






Analyzing the within and between Players Variability of Heart Rate and Locomotor Responses in SSG Performed Repeatedly over a Week

The purpose of this study was to analyze the between-session and within-player variability of heart rates and locomotor responses of young male soccer players in 3v3 and 5v5 small-sided game formats.





Influence of Tactical Behaviour on Running in the 3 Most Successful Soccer Teams During the Season of the Spanish First Division

The purpose of this study was to analyze the influence of tactical behavior on physical performance of the three best Spanish soccer teams.






Latest research in football - week 40 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 The mean and peak physical demands during transitional play and high pressure activities in elite football

Reference: Biol Sport. 2022 Oct;39(4):1055-1064. doi: 10.5114/biolsport.2023.112968. Epub 2022 Feb 4.

Authors: Lukasz Bortnik, Joost Burger, David Rhodes

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Summary: The aim of the present study was to establish the effect of transitional activities (TA) on physical metrics. Global Positioning System technology was utilized on 23 elite outfield footballers over 10 games to quantify absolute metrics per minute such as total distance (TD; m · min-1), sprint distance (SD; m · min-1), the number of high-intensity accelerations and decelerations (A+D; n · min-1), and high-speed running distance (HSRD; m · min-1). TD - total distance; HSRD - high-speed running distance; SD - sprint distance and high-intensity acceleration distance (Acc B3 Dist) were also quantified. Metrics were observed in relation to 4 TA's commonly observed in football matches. Positive Transitions (PT), Negative Transitions (NT), Fast Attacks (FA) and High Pressure Activities (HP). Main effects for transition and game were observed. Comparisons were also made between 90 minute averages and transitional mean scores. NT displayed the highest TD (m · min-1) when compared to other TA's (p ≤ 0.05). Observation of SD (m · min-1) for all transitions highlighted higher outputs when in PT (p ≤ 0.05). HP TA displayed the lowest output in all metrics (p ≤ 0.05), except high-intensity accelerations and decelerations A+D (n · min-1). The mean average and peak average outputs for TA and 90min average detailed elevated physical outputs across all metrics. Absolute physical metrics are increased when observing transitional play, representing the maximum physical exposure that athletes experience in games. This knowledge should be utilized when implementing high-velocity exposures within a weekly microcycle, to best prepare players for match play.



#2 Internal and external load during 8 v 8, 5 v 5 and 3 v 3 in Chinese elite youth male football players

Reference: Biol Sport. 2022 Oct;39(4):1065-1071. doi: 10.5114/biolsport.2022.113292. Epub 2022 Feb 4.

Authors: Zhen Li, Lijuan Mao, Peter Krustrup, Morten B Randers

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Summary: Aim to investigate internal and external load in three different game formats (8 v 8, 5 v 5, 3 v 3 with 80 m2 per player) of small-sided games (SSG) in Chinese elite youth football players. Twenty-nine elite male football players (age: 18.3 ± 0.5 years (mean ± SD), height: 175 ± 6 cm, weight: 65.5 ± 6.3 kg) participated in randomized order in the three formats. Each session consisted of 20 min: 3 v 3 on a 24 × 20-m pitch, 5 v 5 on a 32 × 25-m pitch, or 8 v 8 on a 40 × 32-m pitch all equalling 80 m2 per player. Each player was recorded once in each format. Using GPS-units and heart rate belts and blood lactate measured the two kinds of load. 8-10% higher total distance (P < 0.01) was observed in 8 v 8 and 5 v 5 compared with 3 v 3 (1627 ± 240 and 1595 ± 243 m vs. 1477 ± 179 m, ES = 0.55-0.71). Higher distance (P < 0.001) was covered with high speed running (HSR: > 14 km/h) in 8 v 8 and 5 v 5 than 3 v 3 (154 ± 94 m and 133 ± 59 m vs. 77 ± 35, ES = 1.09-1.15), whereas very high speed running distance (> 21 km/h) was higher (P < 0.01) in 8 v 8 than 5 v 5 and 3 v 3 (15.2 ± 19.5 vs. 5.3 ± 6.7 and 1.0 ± 0.4 m, ES = 0.69-1.03) and in 5 v 5 than 3 v 3. No difference was found between game formats in the number of intense accelerations nor intense decelerations. Blood lactate (3.5 ± 2.3 vs. 2.8 ± 1.9 vs. 2.4 ± 1.5 mmol · L-1, P = 0.201) and mean heart rate (155 ± 21 vs. 160 ± 11 vs. 157 ± 17 bpm, P = 0.254) was not different between 8v8, 5v5 and 3v3 game formats. Distance covered in total and in highest speed zones was higher in SSG formats with more players, which, however, did not lead to differences in internal load measured by heart rate and blood lactate.



#3 Analysis of potential hydration opportunities during future football tournaments based on data from the 2018 FIFA World Cup

Reference: Sci Med Footb. 2022 Oct 17. doi: 10.1080/24733938.2022.2137574. Online ahead of print.

Authors: Floris C Wardenaar, Joshua S Beaumont, Josh Boeckman, Bregje van Geffen, Jennifer K Vanos

Summary: The World Cup is traditionally held during the hot summer months which requires playing in oppressive thermal conditions. Therefore, teams should follow heat strain mitigation strategies, such as acclimatization, pre-exercise cooling, and optimal fluid ingestion. Even though the 2022 World Cup in Qatar is being moved to the autumn to reduce environmental stress, many challenges will remain. The objective of this analysis was to assess and visually communicate match-based World Cup player hydration opportunities and behaviors. Broadcast recordings of the 2018 World Cup (June-July) were analyzed. Descriptive data were reported for match duration, the number, type, and duration of breaks, and player-initiated hydration moments, as well as data reporting environmental conditions using the Universal Thermal Climate Index (UTCI), with matches categorized as "no thermal stress" and "thermal heat stress." The median number and interquartile range of total match breaks were 7 [5-8] during official breaks, with a duration of 42 [23-72] seconds. There were 2 [1-3] player-initiated hydration moments per game, with a duration of 77 [55 to 100] seconds. On top of the 29% (#126) of breaks in which drinking occurred, an additional 26% (#33) of self-initiated drinking was registered with a duration of 7 [4-28] seconds without an official break. There was no significant difference (P=0.22) in self-initiated hydration between matches played under the two thermal conditions. Relative percentages showed suboptimal use of substitution (14%) and VAR (38%) breaks vs. injury breaks (75%). In conclusion, football players did not sufficiently use available breaks to hydrate.



#4 Assessment of the bioaccessibility of PAHs and other hazardous compounds present in recycled tire rubber employed in synthetic football fields

Reference: Sci Total Environ. 2022 Oct 15;159485. doi: 10.1016/j.scitotenv.2022.159485. Online ahead of print.

Authors: Daniel Armada, Antia Martinez-Fernandez, Maria Celeiro, Thierry Dagnac, Maria Llompart

Summary: Recycled tire crumb rubber (RTCR) surfaces contain harmful and carcinogenic substances, which can be ingested by the users of these facilities, mainly athletes and children. In this work, the potential in-vitro oral bioaccessibility of eighteen polycyclic aromatic hydrocarbons (PAHs) from RTCR employed as infill in synthetic football fields was studied in human synthetic body fluids (saliva, gastric, duodenal and bile), prepared according the Unified Bioaccessibility Method. Solid-phase extraction (SPE) using commercial sorbents and a new green material based on cork (cork industry by-product) were used to isolate the bioaccessible PAHs before gas chromatography-tandem mass spectrometry analysis. The method was optimized and validated attending the analytical figures of merit. The feasibility of cork biosorbent for the extraction of the compounds was demonstrated, as well as the suitability of the UBM method to perform the digestion with good precision. The application to real samples collected from football fields demonstrated the presence of 17 of the 18 target PAHs in the biofluids. Most volatile PAHs such as NAP, ACY, ACE, FLU, PHN and ANC, achieved the highest bioaccessibility percentage levels. The carcinogenic B[a]P was detected in 75 % of the samples at concentrations up to 2.5 ng g-1 (bioaccessible fraction). Children exposure assessment was carried out to identify potential risk. Other hazardous and environmentally problematic compounds such as N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-quinone), recently related with the dead of coho salmon, and hexamethoxymethylmelamine (HMMM), among others, were also detected. This is the first study in which the bioaccesibility from real crumb rubber samples of 15 out of the 16 PAHs considered as priority pollutants by the United States Environmental Protection Agency (EPA) and the presence of 6PPD-quinone and HMMM in the bioaccessible fractions was reported.



#5 Effects of the FIFA 11+ and a modified warm-up programme on injury prevention and performance improvement among youth male football players

Reference: PLoS One. 2022 Oct 20;17(10):e0275545. doi: 10.1371/journal.pone.0275545. eCollection 2022.

Authors: Mojtaba Asgari, Mohammad Hossein Alizadeh, Shahnaz Shahrbanian, Kevin Nolte, Thomas Jaitner

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Summary: The effects of the FIFA11+ programme (the 11+) on ankle and groin injuries and performance have remained questionable. The latter, particularly, has potentially reduced the implementation rate and applicability of the programme. This study aimed to evaluate the mid-to-long-term effects of the 11+ and a modified programme including football-specific exercises on injury prevention and performance improvement. Three teams of the Iranian Youth League (division two) volunteered to participate in this study and were randomly assigned to two intervention groups (F11+; n = 29, M11+; n = 31) and a control group (n = 30). The F11+ followed the FIFA 11+ programme, whereas the M11+ performed modified exercises three times weekly as a warm-up protocol before training and competition through a football season. The control group carried out its routine warm-ups, including joggings, basic football drills, and static stretches, while having no injury prevention approaches. Lower extremity injuries, as well as exposure time for each player, were recorded. The football-specific performance was assessed using the Illinois Agility and Slalom Dribbling tests. ANOVA, Fisher Freeman Halton, and chi-square tests were used to analyze the data. Injury incidences differed significantly between groups (p = 0.02, C = 0.40), with M11+ reporting the lowest incidence. Significant differences between the pre- and posttest as well as differences between the groups for development over time were revealed for the Illinois agility and dribbling speed (p≤0.01). Both performance tests demonstrated a large time effect, as the effect sizes for time in agility and dribbling speed were 0.74 (CI = [0.66; 0.79]) and 0.86 (CI = [0.79; 0.87]), respectively. The effect size for the interaction can be categorized as medium, with 0.38 (CI = [0.25; 0.49]) for agility and 0.52 (CI = [0.40; 0.61]) for dribbling speed. M11+ showed the largest improvement in both. Mid-to-long-term application of a structured dynamic warm-up that integrates injury prevention and performance approaches may lower injury incidences and improve youth subelite players' performance. Although additional studies with larger samples are needed to prove the results of the current study, the amateur clubs/teams could integrate such twofold dynamic warm up into their routine training plan and benefit its advantages on injury prevention and performance improvement.



#6 Normative values and changes in range of motion, strength, and functional performance over 1 year in adolescent female football players: Data from 418 players in the Karolinska football Injury Cohort study

Reference: Phys Ther Sport. 2022 Oct 9;58:106-116. doi: 10.1016/j.ptsp.2022.10.003. Online ahead of print.

Authors: Anne Fältström, Eva Skillgate, Ulrika Tranaeus, Nathan Weiss, Henrik Källberg, Victor Lyberg, Mathias Nomme, Nicolai Thome, Truls Omsland, Eirik Pedersen, Martin Hägglund, Markus Waldén, Martin Asker

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Summary: The aim was to study normative values of range of motion (ROM), strength, and functional performance and investigate changes over 1 year in adolescent female football players. 418 adolescent female football players aged 12-17 years participated in this study. The physical characteristic assessments included (1) ROM assessment of the trunk, hips, and ankles; (2) strength measures (maximal isometric and eccentric strength for the trunk, hips, and knees, and strength endurance for the neck, back, trunk and calves), and (3) functional performance (the one-leg long box jump test and the square hop test). Older players were stronger, but not when normalized to body weight. Only small differences in ROM regarding age were found. ROM increased over 1 year in most measurements with the largest change in hip external rotation, which increased by 6-7° (Cohen's d = 0.83-0.87). Hip (d = 0.28-1.07) and knee (d = 0.38-0.53) muscle strength and the square hop test (d = 0.71-0.99) improved over 1 year. Normative values for ROM and strength assessments of neck, back, trunk, hips, knees, calves and ankles are presented for adolescent female football players. Generally, fluctuations in ROM were small with little clinical meaning, whereas strength improved over 1 year.



#7 Spontaneous Pneumomediastinum Resulting From Passionate Cheering at a Soccer Match

Reference: Mil Med. 2022 Oct 15;usac315. doi: 10.1093/milmed/usac315. Online ahead of print.

Authors: Tomer Talmy, Ziv Izhaki, Sami Gendler, Eliad Aviram

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Summary: Spontaneous pneumomediastinum is a rare and self-limiting clinical entity, often triggered by activities causing acute changes in intrathoracic pressure such as childbirth, strenuous exercise, vomiting, and coughing. We present a case of a young male soldier who developed spontaneous pneumothorax following persistent yelling while attending a soccer match. Spontaneous pneumomediastinum may be preceded by a variety of strenuous activities, and clinicians should be aware of this entity when performing the evaluation of patients with nonspecific symptoms such as chest pain and dyspnea. Patients diagnosed with pneumomediastinum but presenting with additional findings such as vomiting and pleural effusion should be thoroughly evaluated to rule out potentially life-threatening mediastinal organ injury. Return to military duty should be determined by clinical reevaluation and follow-up imaging findings.



#8 Effect of physical training on parathyroid hormone and bone turnover marker profile in relation to vitamin D supplementation in soccer players

Reference: Biol Sport. 2022 Oct;39(4):921-932. doi: 10.5114/biolsport.2022.109956. Epub 2021 Nov 10.

Authors: Michał Brzeziański, Monika Migdalska-Sęk, Michał Stuss, Zbigniew Jastrzębski, Łukasz Radzimiński, Ewa Brzeziańska-Lasota, Ewa Sewerynek

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Summary: The aim of the study was to assess the impact of vitamin D supplementation and regular physical activity on 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH) and bone turnover marker concentrations in healthy male athletes. Twenty-five youth soccer players were divided into groups: non-supplemented (GN) and supplemented (GS) with a vitamin D dose of 20 000 IU twice a week for 8 weeks. The study was conducted during an 8-week preseason period, from mid-January to mid-March. At baseline (T1) and at the end of this period (T2), the serum concentrations of 25(OH)D, (PTH), osteocalcin (OC) and β-isomerized C-terminal telopeptide of type I collagen (β-CTx) were measured. At T2, 25(OH)D increased by 70% in GS (p = 0.004) and by 6% in GN (p > 0.05). Significant differences between GS and GN groups were observed throughout the study in the group-by-time interaction and changes of 25(OH)D (p = 0.002; η 2 p = 0.36) and OC (p = 0.008; η 2 p = 0.26). Increased OC (ES = 0.74; moderate) and β-CTx (ES = 1.31, large) in GN athletes who had an optimal baseline vitamin D level (GO) were observed. In GN, at T2, β-CTx positively correlated with PTH and OC (p = 0.007 and p = 0.002). In GS, β-CTx positively correlated with OC at both time points (T1, p = 0.027 and T2, p = 0.037). A negative correlation between 25(OH)D and PTH was observed at T2 (p = 0.018). The obtained results suggest that the 20 000 IU vitamin D3 dose applied twice a week for 8 weeks is effective for vitamin D compensation and sufficient to maintain the correct PTH concentration, as revealed by changes in the bone marker concentrations. In conclusion, the results suggest that the applied vitamin D supplementation dose in athletes leads to intensive bone remodelling and has protective effects on bone under intensive physical effort.



#9 Changes of physical match performance after the COVID-19 lockdown in professional soccer players according to their playing position

Reference: Biol Sport. 2022 Oct;39(4):1087-1093. doi: 10.5114/biolsport.2022.114281. Epub 2022 Apr 21.

Authors: Łukasz Radzimiński, Miguel Lorenzo-Martinez, Marek Konefał, Paweł Chmura, Marcin Andrzejewski, Zbigniew Jastrzębski, Alexis Padrón-Cabo

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Summary: The aim of this study was to evaluate the impact of the pandemic lockdown, which included training cessation and home-based training, on physical performance in professional soccer players from the Polish Ekstraklasa according to their playing position. The research was based on 3137 players' individual match performance observations during the 2019/2020 season divided into before (26 matchdays) and after (11 matchdays) lockdown periods. The data were collected using the computerised multiple-camera optical tracking system TRACAB (ChryronHego VID, New York, NY) with a sampling frequency of 25 Hz. Independently of playing position, a significant (p < 0.001) reduction in season resumption metrics of total distance (-0.9%), jogging (-1.6%), running (-3.4%) and high-speed running (-2.5%), with a contemporaneous increase in walking distance (1.4%), was noted in relation to pre-lockdown performance. A reduction in high-speed running was observed in central defenders (p < 0.05), central midfielders (p < 0.01) and forwards (p < 0.05). No significant decrease in sprinting or maximal running velocity was observed. The COVID-19 lockdown negatively influenced the physical performance in professional soccer players.



#10 The influence of maturity on recovery and perceived exertion, and its relationship with illnesses and non-contact injuries in young soccer players

Reference: Biol Sport. 2022 Oct;39(4):839-848. doi: 10.5114/biolsport.2022.109953. Epub 2021 Oct 25.

Authors: Mauro Mandorino, Antonio J Figueiredo, Giancarlo Condello, Antonio Tessitore

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Summary: A high training load could increase the risk of injury in soccer players. However, there is still a lack of knowledge regarding the effect on young athletes, in whom a different maturity status could lead to different physiological responses to training. Therefore, the aim of this study was to investigate the association of internal load markers and recovery status with risk of illnesses and non-contact injuries in young soccer players characterised by different maturity status. Twenty-three U14 soccer players were monitored during a full season and categorised according to years from peak height velocity (PHV). Based on the estimated values, athletes were divided into three different groups: Pre-PHV, Circa-PHV and Post-PHV players. The following internal load markers were monitored: rating of perceived exertion (RPE), session rating of perceived exertion (S-RPE), weekly load (WL), cumulative loads for 2, 3, and 4 weeks (WL2, WL3, WL4), acute to chronic workload ratio for 2, 3 and 4 weeks (A:C2, A:C3, A:C4) and week-to-week percentage variation (%WL). Recovery status was quantified using the total quality recovery (TQR) scale. Z-score transformation was adopted for TQR and RPE values and the difference between the parameters was calculated (Z-TQR-RPE). The Kruskal-Wallis test was adopted to evaluate differences in TQR and RPE with respect to maturity offset. A multinomial regression analysis was performed to evaluate the association between internal load markers and risk of illness and non-contact injuries. The variables that showed a significant association were included in the receiver operating characteristic (ROC) curve analysis. The results revealed that RPE was significantly higher (p < 0.01) and TQR significantly lower (p < 0.05) in Post-PHV compared to Pre- and Circa-PHV. Moreover, RPE, A:C4, TQR and Z-TQR-RPE showed a significant (p < 0.01) association with non-contact injuries. The internal load markers included in ROC curve analysis showed poor predictive ability (AUC ≤ 0.6). A rapid increase in training load together with a decrease in recovery status may produce higher susceptibility to illnesses and non-contact injuries. The contrasting physiological responses found in relation to maturity status could explain the different injury predisposition in young soccer players.



#11 Do conditioning focused various-sided training games prepare elite youth male soccer players for the demands of competition?

Reference: Biol Sport. 2022 Oct;39(4):825-832. doi: 10.5114/biolsport.2022.109454. Epub 2021 Oct 25.

Authors: Michael G Sydney, Martin Wollin, Dale W Chapman, Nick Ball, Jocelyn K Mara

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Summary: Relative metrics (i.e. distance covered per minute of match time) are regularly used to quantify soccer player movement demands. However, limited literature is available concerning the peak player demands during training. This study aimed to compare the relative and peak demands of conditioning-focused various-sided training games (VSG) to competition matches in elite youth male soccer players according to playing position. Data from twenty-nine competition matches (national) and twenty-two VSGs (small, medium, and large) were collected for twenty-three elite under-17 soccer players using 15-Hz portable global positioning system tracking devices (GPSports, Canberra, Australia). Relative player movements were reported as total distance (TD) and high-speed running distance (HSRD) (> 5.0 m/s) per minute of total playing time. Peak player movements were calculated using a 1-minute rolling epoch length, reported as the maximum TD and HSRD. Linear mixed models demonstrated interactions between VSG type and player position for relative TD (p < 0.001) and HSRD (p < 0.001), and peak TD (p = 0.010) and HSRD (p = 0.003). The relative TD of VSGs were greater than match-play for all player positions. However, only Central Defenders demonstrated similar HSRD in MSGs and LSGs compared to match-play when analysed using relative calculations. External Attackers also replicated match-play relative HSRD demands in LSGs. No VSG type was found to replicate or supersede the peak player movements of match-play across any playing position. Consequently, VSGs should be supplemented with high-speed running training to prepare players for the peak running requirements of match-play.



#12 Comparison of training and match load between metabolic and running speed metrics of professional Spanish soccer players by playing position

Reference: Biol Sport. 2022 Oct;39(4):933-941. doi: 10.5114/biolsport.2022.110884. Epub 2021 Nov 20.

Authors: Berni Guerrero-Calderón, José Alfonso Morcillo, Marcos Chena, Alfonso Castillo-Rodríguez

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Summary: The aims of this study were to compare the training and match load of professional soccer players according to the playing position, and analyse the relationship between the metabolic and running speed metrics. Thirty professional male soccer players belonging to a Spanish First Division team were analysed using global positioning system devices (GPEXE Pro 18.18 Hz) during training and competition (n = 36 training weeks and n = 41 matches). The results showed significant differences between positions on match day; central midfielders covered higher total distance and low- and medium-speed running distance (moderate to large effect size) than central defenders, external defenders and forwards; forwards performed more metabolic power events than central defenders, central midfielders and wide midfielders; and central defenders showed the lowest very-high-speed running. Different patterns were observed in training. Furthermore, the equivalent-distance index showed a strong correlation with accelerations and decelerations events. The main findings were that the physical responses found in training did not correspond with match demands by position; both metabolic and traditional approaches should be used together for load monitoring in professional soccer players; and finally, metabolic power events and the equivalent-distance index seem to be variables that help to differentiate more clearly the characteristics of the player, taking into account their playing position.



#13 A targeted metabolic analysis of football players and its association to player load: Comparison between women and men profiles

Reference: Front Physiol. 2022 Sep 30;13:923608. doi: 10.3389/fphys.2022.923608. eCollection 2022.

Authors: Gil Rodas, Eva Ferrer, Xavier Reche, Juan Daniel Sanjuan-Herráez, Alan McCall, Guillermo Quintás

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Summary: Professional athletes undertake a variety of training programs to enhance their physical performance, technical-tactical skills, while protecting their health and well-being. Regular exercise induces widespread changes in the whole body in an extremely complex network of signaling, and evidence indicates that phenotypical sex differences influence the physiological adaptations to player load of professional athletes. Despite that there remains an underrepresentation of women in clinical studies in sports, including football. The objectives of this study were twofold: to study the association between the external load (EPTS) and urinary metabolites as a surrogate of the adaptation to training, and to assess the effect of sex on the physiological adaptations to player load in professional football players. Targeted metabolic analysis of aminoacids, and tryptophan and phenylalanine metabolites detected progressive changes in the urinary metabolome associated with the external training load in men and women's football teams. Overrepresentation analysis and multivariate analysis of metabolic data showed significant differences of the effect of training on the metabolic profiles in the men and women teams analyzed. Collectively, our results demonstrate that the development of metabolic models of adaptation in professional football players can benefit from the separate analysis of women and men teams, providing more accurate insights into how adaptation to the external load is related to changes in the metabolic phenotypes. Furthermore, results support the use of metabolomics to understand changes in specific metabolic pathways provoked by the training process.



#14 The impact of UEFA Euro 2020 football championship on Takotsubo Syndrome: Results of a multicenter national registry

Reference: Front Cardiovasc Med. 2022 Sep 28;9:951882. doi: 10.3389/fcvm.2022.951882. eCollection 2022.

Authors: Alberto Polimeni, Carmen Spaccarotella, Jessica Ielapi, Giovanni Esposito, Amelia Ravera, Eugenio Martuscelli, Vincenzo Ciconte, Maurizio Menichelli, Ferdinando Varbella, Massimo Imazio, Alessandro Navazio, Gianfranco Sinagra, Rainer Oberhollenzer, Gerolamo Sibilio, Luisa Cacciavillani, Luigi Meloni, Marcello Dominici, Fabrizio Tomai, Francesco Amico, Marco Corda, Giuseppe Musumeci, Alessandro Lupi, Luigi Zezza, Raffaele De Caterina, Carlo Cernetti, Marco Metra, Lidia Rossi, Paolo Calabrò, Adriano Murrone, Massimo Volpe, Pasquale Caldarola, Stefano Carugo, Bernardo Cortese, Renato Valenti, Giuseppe Boriani, Francesco Fedele, Giorgio Ventura, Maria Teresa Manes, Angela Rita Colavita, Mauro Feola, Francesco Versaci, Pasquale Assennato, Giuseppe Arena, Roberto Ceravolo, Vincenzo Amodeo, Gianfranco Tortorici, Daniele Nassiacos, Roberto Antonicelli, Nicolino Esposito, Stefano Favale, Giovanni Licciardello, Luigi Tedesco, Ciro Indolfi

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Summary: The UEFA 2020 European Football Championship held in multiple cities across Europe from June 11 to July 11, 2021, was won by Italy, providing an opportunity to examine the relationship between emotional stress and the incidence of acute cardiovascular events (ACE). Cardiovascular hospitalizations in the Cardiac Care Units of 49 hospital networks in Italy were assessed by emergency physicians during the UEFA Euro 2020 Football Championship. We compared the events that occurred during matches involving Italy with events that occurred during the remaining days of the championship as the control period. ACE was assessed in 1,235 patients. ACE during the UEFA Euro 2020 Football Championship semifinal and final, the most stressful matches ended with penalties and victory of the Italian team, were assessed. A significant increase in the incidence of Takotsubo Syndrome (TTS) by a factor of 11.41 (1.6-495.1, P < 0.003), as compared with the control period, was demonstrated during the semifinal and final, whereas no differences were found in the incidence of ACS [IRR 0.93(0.74-1.18), P = 0.57]. No differences in the incidence of ACS [IRR 0.98 (0.87-1.11; P = 0.80)] or TTS [IRR 1.66(0.80-3.4), P = 0.14] were found in the entire period including all matches of the UEFA Euro 2020 compared to the control period. The data of this national registry demonstrated an association between the semifinal and final of UEFA Euro 2020 and TTS suggesting that it can be triggered by also positive emotions such as the victory in the European Football Championship finals.



#15 Effectiveness of the Functional Movement Screen for assessment of injury risk occurrence in football players

Reference: Biol Sport. 2022 Oct;39(4):889-894. doi: 10.5114/biolsport.2022.107482. Epub 2021 Nov 10.

Authors: Marek Łyp, Marcin Rosiński, Jarosław P Chmielewski, Małgorzata A Czarny-Działak, Magdalena Osuch, Daria Urbańska, Tomasz Wójcik, Magdalena Florek-Łuszczki, Iwona A Stanisławska

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Summary: The aim of the study was to determine whether the Functional Movement Screen (FMS) test carried out among young boys practising football training identifies previous injuries. Sixty-five boys aged 12-13 years, who had regularly practised football in an academy for at least 3 years, were recruited and divided into two groups: an injured group (IG), consisting of players who had experienced at least one injury in the past (n + 25, age 12.32 ± 0.48) and a non-injured group (non-IG), a control group, made up of athletes with no injuries to the musculoskeletal system (n = 40, age 12.25 ± 0.49). Seven FMS tests were used to rate the functional fitness level as a part of the FMS tool. Significant differences between the total scores of the FMS tests (p < 0.001, r = 0.54) were documented. Higher scores in the FMS test were observed in the control group (M = 16.58, SD = 2.04) than in the study group (M = 14.20, ± SD = 1.96). The FMS test is an effective diagnostic tool to identify previous injuries among young football players.



#16 Temporal distribution of peak running demands relative to match minutes in elite football

Reference: Biol Sport. 2022 Oct;39(4):985-994. doi: 10.5114/biolsport.2022.110745. Epub 2021 Dec 30.

Authors: Bradley Thoseby, Andrew D Govus, Anthea C Clarke, Kane J Middleton, Ben J Dascombe

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Summary: The peak match running demands of football (soccer) have been quantified across time durations of 1-10 min, however, little is known as to when the peak match running demands occur within match play. Data were collected from 44 elite footballers, across 68 fixtures (Files = 413, mean ± SD; 11 ± 8 observations per player, range; 1-33), with peak match running demands quantified for each playing half at ten incremental rolling average durations (1 min rolling averages, 2 min rolling averages, etc.). Data were assessed if players completed the full match. Three measures of running performance were assessed total distance (TD), high-speed distance (> 19.8 km · h-1) (HSD) and average acceleration (AveAcc)], with the in-game commencement time of the peak running demands recorded. Descriptive statistics and normality were calculated for each rolling average duration, with the self-containment of shorter rolling average epochs within longer epochs also assessed (e.g. Do the 1 min peak running demands occur within the 10 min peak running demands). Peak TD and AveAcc demands occurred early in each half (median time = 7-17 min and 6-16 min, respectively). Conversely, peak HSD covered was uniformly distributed (Skewness = 0-0.5, Kurtosis = 1.7-2.0). There were low-moderate levels of self-containment for each peak match running period (10-51%), dependent upon metric. Peak match running demands for TD and AveAcc occurred at similar stages of a match where TD and acceleration volumes are typically greatest, whereas peak HSD demands appeared more unpredictable. These timings may help inform training prescriptions in preparation of athletes for competition.



#17 Between-match variation of peak match running intensities in elite football

Reference: Biol Sport. 2022 Oct;39(4):833-838. doi: 10.5114/biolsport.2022.109456. Epub 2021 Oct 25.

Authors: Bradley Thoseby, Andrew D Govus, Anthea C Clarke, Kane J Middleton, Ben J Dascombe

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Summary: Peak match running intensities have recently been introduced to quantify the peak running demands of football competition, across incremental time intervals, to inform training practices. However, their between-match variation is yet to be comprehensively reported, limiting the ability to determine meaningful changes in peak match running intensities. The current study aimed to quantify the between-match variability in peak match running intensities across discrete moving average durations (1-10 min). GPS data were collected from 44 elite football players across 68 matches (mean ± SD; 13 ± 10 observations per player). For inclusion players must have completed 70mins of a match across a minimum of two matches. Performance metrics included total and high-speed (> 19.8 km · h-1) running distances and average acceleration (m · s-2), expressed relative to time. For each metric, the coefficient of variation and smallest worthwhile difference were calculated. The peak match running intensity data was similar to previously reported data from various football competitions. The between-match CV of relative total distance ranged between 6.8-7.3%, with the CV for average acceleration and relative high-speed running being 5.4-5.8% and 20.6-29.8%, respectively. The greater variability observed for relative high-speed running is likely reflective of the varying constraints and contextual factors that differ between matches. The reported between-match variability helps to provide context when interpreting match performance and prescribing training drills using peak match running intensity data.






Quantification of Pre-Season and In-Season Training Intensity across an Entire Competitive Season of Professional Footballers

The aim of this study was to quantify the training load in two microcycles (Ms) from pre- and another two from in-season and to analyze playing position influences on the load experienced by professional soccer players.





Effect of 3 vs. 3 SSG on Various Performance, Inflammatory, Muscle Damage and Hormonal Indicators in Semi-Professional Players

The purpose of this study was to examine the effect of a soccer small-sided game (SSG) on performance, inflammatory, muscle damage and hormonal indicators.





Latest research in football - week 39 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 The Effect of External Dissociative Stimuli on Plank Duration Performed by Male Collegiate Soccer Players

Reference: J Strength Cond Res. 2022 Oct 12. doi: 10.1519/JSC.0000000000004371. Online ahead of print.

Authors: Michele N D'Agata, Jason P Staub, Daniel J Scavone, Gregory M Kane

Summary: Individuals commonly use music as an external auditory stimulus to divert their attention away from aerobic endurance exercise tasks. Music generally results in lower ratings of perceived exertion, which may be the mechanism by which it increases aerobic exercise task duration. However, less is known regarding how music affects the performance of other forms of exercise, such as isometric exercise. Moreover, the effects of different external stimuli on isometric task duration, such as the use of virtual reality (VR), have yet to be investigated. Therefore, the purpose of this study was to investigate the effects of self-selected music (SSM) and VR on isometric exercise task duration using a forearm plank. We hypothesized that both SSM and VR would effectively increase plank duration compared with no external stimuli. Seventeen male collegiate soccer players (19 ± 1 year) completed 3 planks to failure on 3 separate days, with 48-72 hours between the trials. The ordering of each exercise condition (SSM, VR, or None) was randomized for a total of 6 potential orders. A one-way repeated-measures analysis of variance was used to evaluate differences in plank duration and average heart rate (HRavg) between each trial, and significance was set at p < 0.05. There were no differences in plank duration (SSM: 200 ± 44, VR: 173 ± 38, None: 177 ± 37 seconds) or HRavg (SSM: 96 ± 18, VR: 92 ± 21, None: 87 ± 18 beats per minute) between the conditions. We conclude that there was no effect of external stimuli (SSM or VR) on isometric exercise task duration and the use of these modalities should be based on exerciser preference.



#2 Individualized reference ranges for markers of muscle recovery assessment in soccer

Reference: Eur J Sport Sci. 2022 Oct 13;1-44. doi: 10.1080/17461391.2022.2134052. Online ahead of print.

Authors: Sabrina Skorski, Werner Pitsch, Vanessa Barth, Max Walter, Mark Pfeiffer, Alexander Ferrauti, Michael Kellmann, Anne Hecksteden, Tim Meyer

Summary: Recently an individualization algorithm has been developed and shown to significantly improve diagnostic accuracy of creatine kinase (CK) and urea in endurance sports and Badminton. In this study, applicability and benefit of this algorithm was evaluated using repeated measures data from 161 professional German soccer players monitored during the 2015-2017 seasons. Venous blood samples were collected after a day off (recovered state) and after a minimum of two strenuous training sessions within 48 h (non-recovered state) and analyzed for CK and urea. Group-based reference ranges were derived from that same dataset to ensure a best possible reference for comparison. A z-Test was conducted to analyse differences in error rates between individualized and group-based classifications. CK values for the individualized approach showed significantly lower error rates in the assessment of muscle recovery compared to both a population-based (p<0.001; z-value: -17.01; test-pass error rate: 21 vs. 67%; test-fail: 19 vs. 64%) and a group-based cut-off (p<0.001; z-value: -15.29; test-pass error rate: 65%; test-fail: 67%). It could be concluded that the assessment of muscle recovery in soccer using individualized interpretations of blood-borne markers may offer higher diagnostic accuracy as compared to a population-based as well as a sample specific group-based approach.Key points: Assessing muscle recovery via CK using individualized ranges seems to offer a higher diagnostic accuracy compared to a sample-specific group-based analysis.Using an individualized algorithm seems to be a promising approach to overcome diagnostic problems arising from large inter- and intraindividual variability in blood parameters as it significantly improved the diagnostic accuracy of CK as a recovery marker.As recovery assessment in elite soccer ultimately aims at the accurate detection of differences in the individual player this algorithm seems to offer coaches and sport scientists a more sensitive approach compared to group-specific evaluations.



#3 Kinetic Effects of 6 Weeks' Pilates or Balance Training in College Soccer Players with Chronic Ankle Instability

Reference: Int J Environ Res Public Health. 2022 Oct 8;19(19):12903.  doi: 10.3390/ijerph191912903.

Authors: Quan Jiang, Yonghwan Kim, Moonyoung Choi

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Summary: Lateral ankle sprain (LAS) is a common sports injury that frequently occurs in active individuals. LAS is characterized by a high recurrence rate, with a large proportion of patients progressing to chronic ankle instability (CAI). Pilates exercises have provided positive results in health care and in rehabilitation. This study compared Pilates training (PT) with traditional balance training (BT) in patients with CAI. Fifty-one college football players with CAI, divided into PT (n = 26) and BT (n = 25) groups, were included in the study. The groups performed PT or BT training as assigned, three times per week for 6 weeks. Isokinetic ankle strength, one-leg hop tests, Y-balance test (YBT), and foot and ankle outcome score (FAOS) were evaluated before and after training. There were considerable improvements in both the PT and BT groups after training. Group and time comparisons revealed that the PT group achieved better triple hop test results than the BT group, whereas the BT group exhibited a greater improvement in YBT posteromedial and posterolateral reach distances. In athletes with CAI, both PT and BT effectively improved symptoms and function. These findings suggest that ankle strength, balance, and core stability should be comprehensively evaluated and targeted in CAI rehabilitation programs.



#4 Exploring the Effects of a Neck Strengthening Program on Purposeful Soccer Heading Biomechanics and Neurocognition

Reference: Int J Sports Phys Ther. 2022 Oct 2;17(6):1043-1052. doi: 10.26603/001c.38327. eCollection 2022.

Authors: Katelyn M Waring, Edward R Smith, Gary P Austin, Thomas G Bowman

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Summary: Cervical (neck) strengthening has been proposed as an important factor in concussion prevention. The purpose of the study was to determine if a six-week cervical strengthening program affected neurocognition and purposeful soccer heading biomechanics. The hypothesis was that the neck strengthening program would improve strength, maintain neurocognition, and alter purposeful soccer heading biomechanics. Twenty collegiate soccer athletes (8 males, 12 females, age=20.15±1.35 years, height=171.67±9.01 cm, mass=70.56±11.03 kg) volunteered to participate. Time (pre, post) and group (experimental, control) served as the independent variables. Four composite scores from the CNS Vital Signs computer based neurocognitive test (CNSVS; verbal memory, visual memory, executive function, reaction time) and aspects of heading biomechanics from inertial measurement units (xPatch; peak linear acceleration, peak rotational acceleration, duration, Gadd Severity Index [GSI]) served as the dependent variables. Each athlete completed a baseline measure of neck strength (anterior neck flexors, bilateral anterolateral neck flexors, bilateral cervical rotators) and CNSVS after heading 10 soccer balls at two speeds (11.18 and 17.88 m/s) while wearing the xPatch. The experimental group completed specific cervical neck strengthening exercises twice a week for six weeks using a Shingo Imara™ cervical neck resistance apparatus while the control group did not. After six weeks, the participants completed the same heading protocol followed by measurement of the same outcome variables. The alpha value was set to p<0.05 a priori. The interaction between time and group was significant for visual memory (F1,17=5.16, p=0.04, η2=0.23). Interestingly, post hoc results revealed visual memory decreased for the control group from pretest (46.90±4.46) compared to posttest (43.00±4.03; mean difference=3.90, 95% CI=0.77-7.03, p=0.02). Interactions for all other dependent variables were not statistically significant (p>0.05). The cervical neck strengthening protocol allowed maintenance of visual memory scores but did not alter other neurocognitive measures or heading biomechanics. The link between cervical neck strengthening and concussion predisposition should continue to be explored.



#5 Non-header impact exposure and kinematics of male youth soccer players 

Reference: Biomed Sci Instrum. 2021 Apr;57(2):106-113. doi: 10.34107/yhpn9422.04106.

Authors: Declan A Patton, Colin M Huber, Susan S Margulies, Christina L Master, Kristy B Arbogast

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Summary: Previous studies have investigated the head impact kinematics of purposeful heading in youth soccer; however, less than a third of all head injuries in youth soccer have been found to involve ball contact. The aim of the current study was to identity the head impact kinematics and exposure not associated with purposeful heading of the ball in male youth soccer. Headband-mounted sensors were used to monitor the head kinematics of male junior varsity and middle school teams during games. Video analysis of sensor-recorded events was used to code impact mechanism, surface and site. Junior varsity players had non-header impact rates of 0.28 per athlete-exposure (AE) and 0.37 per player-hour (PH), whereas middle school players had relatively lower non-header impact rates of 0.16 per AE and 0.25 per PH. Such impact rates fell within the large range of values reported by previous studies, which is likely affected by sensor type and recording trigger threshold. The most common non-header impact mechanism in junior varsity soccer was player contact, whereas ball-to-head was the most common non-header impact mechanism in middle school soccer. Non-header impacts for junior varsity players had median peak kinematics of 31.0 g and 17.4 rad/s. Non-header impacts for middle school players had median peak kinematics of 40.6 g and 16.2 rad/s. For non-header impacts, ball impacts to the rear of the head the highest peak kinematics recorded by the sensor. Such data provide targets for future efforts in injury prevention, such as officiating efforts to control player-to-player contact.



#6 Sports Injuries of a Portuguese Professional Football Team during Three Consecutive Seasons

Reference: Int J Environ Res Public Health. 2022 Oct 2;19(19):12582. doi: 10.3390/ijerph191912582.

Authors: Francisco Martins, Cíntia França, Adilson Marques, Beatriz Iglésias, Hugo Sarmento, Ricardo Henriques, Andreas Ihle, Helder Lopes, Rui T Ornelas, Élvio Rúbio Gouveia

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Summary: Professional football players are exposed to high injury risk due to the physical demands of this sport. The purpose of this study was to characterize the injuries of a professional football team in the First Portuguese League over three consecutive sports seasons. Seventy-one male professional football players in the First Portuguese Football League were followed throughout the sports seasons of 2019/2020, 2020/2021, and 2021/2022. In total, 84 injuries were recorded. Each player missed an average of 16.6 days per injury. Lower limbs were massively affected by injuries across all three seasons, mainly with muscular injuries in the quadriceps and hamstrings and sprains in the tibiotarsal structure. Overall, the injury incidence was considerably higher in matches than in training. The two times of the season that proved most conducive to injuries were the months of July and January. Our results emphasize the importance of monitoring sports performance, including injury occurrence, and assisting in identifying risk factors in professional football. Designing individualized training programs and optimizing prevention and recovery protocols are crucial for maximizing this global process.



#7 Injury incidence rates in women's football: a systematic review and meta-analysis of prospective injury surveillance studies

Reference: Br J Sports Med. 2022 Oct 13;bjsports-2021-105177. doi: 10.1136/bjsports-2021-105177.

Authors: Dan Horan, Fionn Büttner, Catherine Blake, Martin Hägglund, Seamus Kelly, Eamonn Delahunt

Summary: The aim was to review the literature to establish overall, match and training injury incidence rates (IIRs) in senior (≥18 years of age) women's football (amateur club, elite club and international). Databases such as MEDLINE via PubMed; EMBASE via Ovid; CINAHL via EBSCO and Web of Science were searched from earliest record to July 2021. Studies were elected if 1) football players participating in a senior women's football league (amateur club or elite club) or a senior women's international football tournament; (2) the study had to report IIRs or provide sufficient data from which this outcome metric could be calculated through standardised equations; (3) a full-text article published in a peer-reviewed journal before July 2021; (4) a prospective injury surveillance study and (5) case reports on single teams were ineligible. 17 articles met the inclusion criteria; amateur club (n=2), elite club (n=10), international (n=5). Overall, match and training 'time-loss' IIRs are similar between senior women's elite club football and international football. 'Time-loss' training IIRs in senior women's elite club football and international football are approximately 6-7 times lower than their equivalent match IIRs. Overall 'time-loss' IIRs stratified by injury type in women's elite club football were 2.70/1000 hours (95% CI 1.12 to 6.50) for muscle and tendon, 2.62/1000 hours (95% CI 1.26 to 5.46) for joint and ligaments, and 0.76/1000 hours (95% CI 0.55 to 1.03) for contusions. Due to the differences in injury definitions, it was not possible to aggregate IIRs for amateur club football. Lower limb injuries incurred during matches are a substantial problem in senior women's football. The prevention of lower limb joint, ligament, muscle and tendon injuries should be a central focus of injury prevention interventions in senior women's amateur club, elite club and international football.



#8 Fitness Soccer Athletes Training at the University of Limpopo, South Africa: Are the Macronutrients Intake and Anthropometric Status of These Athletes Optimal?

Reference: Int J Environ Res Public Health. 2022 Oct 3;19(19):12650. doi: 10.3390/ijerph191912650.

Authors: Masodi Makhafola, Hendrick Makhubela, Sylven Masoga, Sefora Hazel Makuse

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Summary: Dietary practices of the University of Limpopo soccer team athletes have been reported. However, the practices of those engaging in soccer for general fitness from different non-competitive teams remain unknown. To respond to this gap, the researchers investigated the energy, macronutrient intake, and BMI status and further correlated the two variables of the fitness non-competitive soccer athletes registered at the University of Limpopo in South Africa. A quantitative study design was undertaken to conveniently sample 60 out of 90 fitness soccer athletes from the four non-competitive soccer teams at the University of Limpopo sports grounds. Ethics approval was obtained from the University of Limpopo Research and Ethics Committee, and permission was given by the university sports management and team coaches. Athletes signed the informed consent form before participating in the study. Data were collected at the soccer fields during the afternoons before the start of training. Macronutrient intake data were collected using multiple (two) 24-h recall questionnaires on different days, which were validated by the food frequency questionnaire. Weight and height were measured using a digital scale (Seca 813 electronic flat scale) and stadiometer (Seca 213 portable stadiometer) for BMI calculations, respectively. The average energy and macronutrient intakes were calculated through the SAMRC FoodFinder software (3.0). The nutrient averages, together with the BMI results, were loaded into SPSS (26.0) for further analysis. Descriptive statistics were used to report the energy, macronutrient intake, and BMI statuses of athletes using percentages, means, and standard deviations (±SD). A one-way ANOVA test was used to determine the association between the latter variables. A p-value of ≤ 0.05 was the criterion used to correlate the variables. All (100%) athletes were males, most of whom played soccer for 2-3 years while at the university. Almost half (48%) of athletes consumed energy (39.6 kcal/kg) below the recommendations. About 92% and 53% of athletes consumed carbohydrates (5.0 g/kg) and fat (1.2 g/kg) below the recommended values; while 43% consumed protein (1.4 g/kg) optimally. The majority (&gt;80%) had a normal BMI (21.6 ± 2.6 kg/m2) status. However, there were no relationships between the energy (p = 0.383), CHO (p = 0.261), protein (p = 0.543), and fat (p = 0179) intake and the BMI status of athletes. The macronutrient intake of fitness soccer athletes at the University of Limpopo is, on the whole, suboptimal. However, the athletes had normal body weights. There was no association between both the energy and macronutrient intake and the anthropometric (BMI) status of soccer athletes.



#9 Are sprint accelerations related to groin injuries? A biomechanical analysis of adolescent soccer players

Reference: Sports Biomech. 2022 Oct 19;1-13. doi: 10.1080/14763141.2022.2133740. Online ahead of print.

Authors: Thomas Dupré, Wolfgang Potthast

Summary: Groin injuries have one of the highest incidences in soccer and can be career threatening, especially for adolescents, due to their high recurrence rate. Quick accelerations have been connected to groin injuries along with kicking and change of directions. Purpose of this study was to examine the hip joint kinematics, kinetics and the muscle forces of adductor longus and gracilis during first ground contact of a linear sprint acceleration performed by adolescent soccer players. Twenty-two male participants were investigated with 3D motion capture and two force plates. Inverse dynamics were used to calculate the kinematics, kinetics and muscle forces. The kinematics show a constant extension during the stance phase and a quick transition from an abduction to an adduction movement at 90% stance, which coincides with the highest forces in adductor longus and gracilis. This indicates a high load on the adductor muscles due to eccentric contractions combined with high muscle forces in the adductors. Compared to previously investigated inside passing and change of direction movements, adductor muscle forces and angular velocities are higher in this study. Therefore, it is suggested that sprint accelerations are likely to be connected to the development of groin injuries in adolescent soccer players.



#10 Finite Element Analysis of Soccer Ball-Related Ocular and Retinal Trauma and Comparison with Abusive Head Trauma

Reference: Ophthalmol Sci. 2022 Feb 20;2(2):100129. doi: 10.1016/j.xops.2022.100129. eCollection 2022 Jun.

Authors: Matthew R Lam, Pengfei Dong, Yasin Shokrollahi, Linxia Gu, Donny W Suh

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Summary: Trauma to the eye resulting from a soccer ball is a common sports-related injury. Although the types of ocular pathologic features that result from impact have been documented, the underlying pathophysiologic mechanics are not as well studied. The purpose of this study was to evaluate the biomechanical events after the collision of a soccer ball with the eye to better understand the pathophysiology of observed ocular and retinal injuries and to compare them with those observed in abusive head trauma (AHT). A finite element model of the eye was used to investigate the effects of a collision of a soccer ball on the eye. Intraocular pressure and stress were used as outcome measures. Impact of the soccer ball with the eye generated a pressure wave that traveled through the vitreous, creating transient pockets of high and negative pressure. During the high-frequency phase, pressure in the vitreous near the posterior pole ranged from 39.6 to -30.9 kPa. Stress in ocular tissue was greatest near the point of contact, with a peak of 66.6 kPa. The retina experienced the greatest stress at the vasculature, especially at distal branches, where stress rose to 15.4 kPa. On average, retinal stress was greatest in the subretinal layer, but was highest in the preretinal layer when considering only vascular tissue. The high intraocular pressure and stress in ocular tissue near the point of soccer ball impact suggest that injuries to the anterior segment of the eye can be attributed to direct transmission of force from the ball. The subsequent propagation of a pressure wave may cause injuries to the posterior segment as the positive and negative pressures exert compressive and tractional forces on the retina. The linear movement of the pressure wave likely accounts for localization of retinal lesions to the posterior pole or superior temporal quadrant. The primarily linear force in soccer ball trauma is the probable cause for the more localized injury profile and lower retinal hemorrhage incidence compared with AHT, in which repetitive angular force is also at play.



#11 Comprehensive training load monitoring with biomarkers, performance testing, local positioning data, and questionnaires - first results from elite youth soccer

Reference: Front Physiol. 2022 Oct 3;13:1000898. doi: 10.3389/fphys.2022.1000898. eCollection 2022.

Authors: Nils Haller, Julia C Blumkaitis, Tilmann Strepp, Anna Schmuttermair, Lorenz Aglas, Perikles Simon, Elmo Neuberger, Christina Kranzinger, Stefan Kranzinger, James O'Brien, Bernd Ergoth, Stefan Raffetseder, Christian Fail, Manfred Düring, Thomas Stöggl

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Summary: Load management, i.e., prescribing, monitoring, and adjusting training load, is primarily aimed at preventing injury and maximizing performance. The search for objective monitoring tools to assess the external and internal load of athletes is of great interest for sports science research. In this 4-week pilot study, we assessed the feasibility and acceptance of an extensive monitoring approach using biomarkers, neuromuscular performance, and questionnaires in an elite youth soccer setting. Eight male players (mean ± SD: age: 17.0 ± 0.6 years, weight: 69.6 ± 8.2 kg, height: 177 ± 7 cm, VO2max: 62.2 ± 3.8 ml/min/kg) were monitored with a local positioning system (e.g., distance covered, sprints), biomarkers (cell-free DNA, creatine kinase), questionnaires, neuromuscular performance testing (counter-movement jump) and further strength testing (Nordic hamstring exercise, hip abduction and adduction). Feasibility was high with no substantial impact on the training routine and no adverse events such as injuries during monitoring. Adherence to the performance tests was high, but adherence to the daily questionnaires was low, and decreased across the study period. Occasional significant correlations were observed between questionnaire scores and training load data, as well as between questionnaire scores and neuromuscular performance. However, due to the small sample size, these findings should be treated with caution. These preliminary results highlight the feasibility of the approach in elite soccer, but also indicate that modifications are needed in further large-scale studies, particularly in relation to the length of the questionnaire.



#12 Effects of playing 1 vs 3 matches in a one-week period on physical performance in young soccer players

Reference: Biol Sport. 2022 Oct;39(4):819-823. doi: 10.5114/biolsport.2022.108700. Epub 2021 Oct 25.

Authors: Jose Luis Hernández-Davo, Víctor Moreno Pérez, Pedro Moreno Navarro

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Summary: The aim of this study was to analyse the effects of playing 1 vs 3 matches in a one-week period on physical performance in young soccer players. Twelve youth soccer players completed a battery of physical tests (countermovement jump [CMJ], 25 m sprint, 5-0-5 agility test, ankle dorsiflexion range of motion [AD ROM]) 72 h after a match. These tests were performed on two different occasions: during a week with 1 competitive match, and during a week in which 3 matches were played. Three matches in a week caused from most likely to very likely impairments in CMJ (ES = 0.81), the 5-0-5 agility test (ES = 1.03), and in AD ROM (ES = 0.46-0.63) compared with the 1 match in a week. For the 25 m sprint test, performance impairments were found in the split times for 10-15 m (ES = 0.72), 15-20 m (ES = 0.52) and 20-25 m (ES = 0.90) compared with 1 match in a week. Jumping, sprinting, change of direction (COD) performance and AD ROM are significantly affected during congested calendars in young soccer players. The monitoring of these variables is a useful tool to assess players' recovery and may help in determining players' readiness for the next matches.



#13 Movement Regularity Differentiates Specialized and Nonspecialized Athletes in a Virtual Reality Soccer Header Task

Reference: J Sport Rehabil. 2022 Oct 20;1-8. doi: 10.1123/jsr.2021-0432. Online ahead of print.

Authors: Christopher D Riehm, Scott Bonnette, Michael A Riley, Jed A Diekfuss, Christopher A DiCesare, Andrew Schille, Adam W Kiefer, Neeru A Jayanthi, Stephanie Kliethermes, Rhodri S Lloyd, Mathew W Pombo, Gregory D Myer

Summary: Young athletes who specialize early in a single sport may subsequently be at increased risk of injury. While heightened injury risk has been theorized to be related to volume or length of exposure to a single sport, the development of unhealthy, homogenous movement patterns, and rigid neuromuscular control strategies may also be indicted. Unfortunately, traditional laboratory assessments have limited capability to expose such deficits due to the simplistic and constrained nature of laboratory measurement techniques and analyses. To overcome limitations of prior studies, the authors proposed a soccer-specific virtual reality header assessment to characterize the generalized movement regularity of 44 young female athletes relative to their degree of sport specialization (high vs low). Participants also completed a traditional drop vertical jump assessment. During the virtual reality header assessment, significant differences in center of gravity sample entropy (a measure of movement regularity) were present between specialized (center of gravity sample entropy: mean = 0.08, SD = 0.02) and nonspecialized center of gravity sample entropy: mean = 0.10, SD = 0.03) groups. Specifically, specialized athletes exhibited more regular movement patterns during the soccer header than the nonspecialized athletes. However, no significant between-group differences were observed when comparing participants' center of gravity time series data from the drop vertical jump assessment. This pattern of altered movement strategy indicates that realistic, sport-specific virtual reality assessments may be uniquely beneficial in exposing overly rigid movement patterns of individuals who engage in repeated sport specialized practice.



#14 Differences in lower leg kinetics of soccer instep kicking between female and male players

Reference: Sports Biomech. 2022 Oct 20;1-12. doi: 10.1080/14763141.2022.2133738. Online ahead of print.

Authors: Tsuyoshi Iitake, Maya Hioki, Hitoshi Takahashi, Hiroyuki Nunome

Summary: We aimed to clarify the difference in lower leg segment kinetics of soccer instep kicking between female and male players. Instep kicking motions of seven female and seven male university soccer players were captured at 500 Hz. Lower leg angular velocity, knee joint moment and the interaction moment acting on the lower leg were calculated. Discrete variables were compared using two sample-t-test, and statistical parametric mapping were used to compare the time-series changes between the two groups. Although female players maintained a comparable magnitude of lower leg angular velocity, they exhibited significantly lower knee extension moment in the latter part of kicking and significantly smaller forward angular impulse due to that moment. In contrast, female players were found to have a comparable magnitude of angular impulse due to forward component of interaction moment to that of male players. Eventually, female players come to have significantly larger ratio of angular impulses (forward interaction moment/knee extension moment) than male players. It can be considered that the forward component of interaction moment acting on the lower leg of female players may compensate their reduced exertion of knee extension moment, thereby achieving a comparable lower leg angular velocity to that of male players.



#15 Influence of the COVID-19 lockdown on Spanish professional soccer teams' external demands according to their on-field ranking

Reference: Biol Sport. 2022 Oct;39(4):1081-1086. doi: 10.5114/biolsport.2022.113294. Epub 2022 Feb 18.

Authors: Javier Raya-González, Tomás García-Calvo, Ana Rubio-Morales, Roberto López Del Campo, Ricardo Resta, José Carlos Ponce-Bordón

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Summary: The main objective of this study was to analyse the changes in external demand parameters (e.g., total distance, high-speed running distance, accelerations/decelerations) in Spanish professional soccer teams after the COVID-19 lockdown considering their on-field ranking (i.e., teams whose ranking worsened after the COVID-19 lockdown [WRS] vs. teams that improved their ranking after the COVID-19 lockdown [IMP]). A total of 23,527 individual match observations were collected on players competing during the 2019/20 season in the First Spanish Professional soccer League (LaLiga). Goalkeepers and players who participated for less than 10 minutes in each match were excluded. Relative total distance (TD/min), distance covered at 21-24 km · h-1 (HIRD/min) and > 24 km · h-1 per minute (VHIRD/min), high metabolic load distance (HMLD), and the number of accelerations (3 m/s2) and decelerations (< 3 m/s2) performed were analysed by the ChryonHego video-tracking system. These variables were analysed during two differentiated periods, before the COVID-19 lockdown (i.e., 27 matches) and after the COVID-19 lockdown (i.e., 11 matches), and teams were classified into two groups according to their ranking (i.e., WRS vs. IMP). R-Studio was employed for data analysis and a mixed linear model was conducted. A decrease in external demands in all teams after the COVID-19 lockdown was observed, and this decrease was greater in WRS. These results suggest that, after an inactive period (i.e., the COVID-19 lockdown), teams that return with better physical performance, mainly related to high-intensity actions, have more possibilities of improving their final qualifying position.



#16 A novel multifactorial hamstring screening protocol: association with hamstring muscle injuries in professional football (soccer) - a prospective cohort study

Reference: Biol Sport. 2022 Oct;39(4):1021-1031. doi: 10.5114/biolsport.2022.112084. Epub 2021 Dec 30.

Authors: Johan Lahti, Jurdan Mendiguchia, Pascal Edouard, Jean-Benoit Morin

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Summary: The aim of this pilot study was to analyze the potential association of a novel multifactorial hamstring screening protocol with the occurrence of hamstring muscle injuries (HMI) in professional football. 161 professional male football players participated in this study (age: 24.6 ± 5.36 years; body-height: 180 ± 7.07 cm; body-mass: 77.2 ± 7.70 kg). During the pre- and mid-season, players performed a screening protocol consisting of 11 tests aimed to evaluate their performance in regards to four main musculoskeletal categories: posterior chain strength, sprint mechanical output, lumbopelvic control and range of motion. Univariable cox regression analysis showed no significant association between the isolated test results and new HMI occurrence during the season (n = 17) (p > 0.05). When including injuries that took place between the pre- and mid-season screenings (~90 days), maximal theoretical horizontal force (F0) was significantly associated with higher HMI risk between pre- and mid-season evaluations (n = 14, hazard ratio; 4.02 (CI95% 1.08 to 15.0, p = 0.04). This study identified that 1) no single screening test was sufficient to identify players at risk of HMI within the entire season, while 2) low F0 was associated with increased risk of HMI when occurring closer to the moment of screening. The present results support the potential relevance of additionally including frequent F0 testing for HMI risk reduction management. Replication studies are needed in larger cohorts for more accurate interpretations on "univariable and multivariable levels levels. Finally, future studies should explore whether improving F0 is relevant within a multifactorial HMI risk reduction approach.



#17 Effects of mental fatigue on the psychophysiological responses, kinematic profiles, and technical performance in different small-sided soccer games

Reference: Biol Sport. 2022 Oct;39(4):965-972. doi: 10.5114/biolsport.2022.110746. Epub 2021 Dec 30.

Authors: Yusuf Soylu, Fikret Ramazanoglu, Ersan Arslan, Filipe Manuel Clemente

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Summary: The purpose of this study was to assess the effects of mental fatigue (MF) on the psychophysiological responses, kinematic profiles, and technical performance of young soccer players in small-sided games (SSGs). Twenty-four young soccer players (age: 15.9 ± 1.0 years) played 2vs2, 3vs3, and 4vs4 SSGs consisting of four bouts (with two-minute passive rest periods between bouts) under two different playing conditions: MF+SSGs and SSGs. The heart rate, total distance covered, and technical performance of each player were monitored during all SSGs, and the rating of perceived exertion, visual analogue scale, and Rating Scale Mental Effort values were determined after each bout. The Physical Activity Enjoyment Scale (PACES) and Brunel Mood Scale (BRUMS) were also determined at the end of each SSG. The results demonstrated that all MF+SSGs induced higher psychophysiological responses (p ≤ 0.05) than SSGs, except regarding the PACES responses. By contrast, the SSGs group covered a greater total distance (p ≤ 0.05) than the MF+SSGs group. During SSGs, the players' technical performances (in terms of lost balls and unsuccessful passes) were negatively affected after MF (p ≤ 0.05). The results of this study indicate that both PACES scores and mood responses were negatively affected after the MF intervention. Coaches could use the MF intervention before SSGs to improve soccer-specific technical and decision-making performances in young soccer players.



#18 Perception and application of flywheel training by professional soccer practitioners

Reference: Biol Sport. 2022 Oct;39(4):809-817. doi: 10.5114/biolsport.2022.109457. Epub 2021 Oct 25.

Authors: Kevin L de Keijzer, Stuart A McErlain-Naylor, Thomas E Brownlee, Javier Raya-González, Marco Beato

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Summary: Growing evidence supports use of eccentric methods for strength development and injury prevention within elite soccer, yet uncertainty remains regarding practitioners' application of flywheel (isoinertial) methods. The aims of this study were to investigate how the flywheel training literature is perceived and applied by elite soccer practitioners, highlight gaps in knowledge and develop industry-relevant research questions. Fifty-one practitioners completed an electronic questionnaire. Fourteen Likert scale statements were grouped into topics: strength and performance; post-activation performance enhancement and methodological considerations; chronic strength; chronic performance; injury prevention. Three general questions followed, allowing more detail about flywheel training application. A Majority of the participants reported ≥ 2 years' experience of programming flywheel training. Nearly all participants agreed that familiarisation is needed. Practitioners agree that flywheel training can improve sport performance, strength and likelihood of non-contact injury outcomes. Most practitioners prescribe 2 weekly sessions during pre- and in-season periods. Flywheel sessions mostly consist of squats but a variety of exercises (lunge, hip hinge, and open kinetic chain) are also frequently included. Practitioners are mostly unsure about differences between flywheel and traditional resistance training equipment and outcomes, practicality of flywheel equipment, and evidence-based guidelines. The investigation provides valuable insight into the perspectives and application of flywheel training within elite soccer, highlighting its perceived efficacy for strength and injury prevention.






Physiological and locomotor demands during small‑sided games are related to match demands and physical fitness?

The purpose of the study was: (i) to analyze the relationships of physiological and locomotor demands between small-sided games (3v3 and 5v5) and official matches (11v11); (ii) to analyze the relationships between small-sided games demands and the physical fitness of youth soccer players.





Immediate effect of stabilization exercises versus conventional exercises of the trunk on dynamic balance among trained footballers

Trunk stability is key in controlling body balance and movements. Trunk Stabilization Exercises (TSE) and Conventional Trunk Exercises (CTE) are performed to improve dynamic balance. The aim was to compare the immediate effect of TSE with that of CTE on dynamic balance in trained soccer players.





Latest research in football - week 38 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Effects of osteopathic manipulative treatment of the pivots on lower limb function in young professional football players

Reference: J Bodyw Mov Ther. 2022 Oct;32:1-6. doi: 10.1016/j.jbmt.2022.05.017. Epub 2022 May 19.

Authors: Ewan Thomas, Marco Petrucci, Massimo Barretti, Giuseppe Messina, Antonio Rosario Cavallaro, Antonino Bianco

Summary: The most frequent injuries in professional soccer players are those pertinent to the lower limbs. In particular, strains of the hamstrings and ligamentous injuries of the knee. Therefore, preventive measures are aimed to reduce such events. We aimed to investigate if an osteopathic manipulative treatment (OMT) of the pivots could improve lower limb function in young professional football players. Thirty-eight young male professional football players were recruited (mean age 17.8 ± 0.44 years). These were randomly assigned to an OMT or control group (n = 20 and 18, respectively). Both groups underwent osteopathic evaluation. A sit-and-reach test, a vertical jump test, a hand-grip strength test, a cervical ROM test and a balance evaluation were also performed. A significant improvement (p < 0.01) was observed between pre and post measures in the OMT for dysfunctional assessment of the pivots. However, only L3 and C2 also differed from the control group post evaluation (p < 0.0001). No differences were present for any functional measure in the control group. Only the sit-&-reach of the OMT increased significantly (p < 0.001). Static balance with open eyes in the OMT, but not in the control group, improved during post evaluation (p < 0.01). The OMT of the pivots was able to increase the sit-and-reach measure, improve postural control with open eyes and improve dysfunctional patterns of the lumbosacral and upper cervical spine in young professional football players.



#2 Prevalence of Dehydration and The Relationship with Fluid Intake and Self-Assessment of Hydration Status in Czech First League Soccer Players

Reference: J Hum Kinet. 2022 Apr 26;82:101-110.doi: 10.2478/hukin-2022-0035. eCollection 2022 Apr.

Authors: Iva Klimesova, Jakub Krejci, Michal Botek, Andrew J McKune, Ales Jakubec, Filip Neuls, Barbora Sladeckova, Michal Valenta

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Summary: The objective of this cross-sectional study was to evaluate the hydration status of Czech First League soccer players, and to compare the reported fluid intake, perceived fluid intake and thirst sensation of euhydrated (EU) and dehydrated (DE) players. The study involved 124 Czech male professional soccer players (age 25.2±5.0 years) participating in annual winter, pre-season laboratory testing. Hydration status was assessed based on urine specific gravity (USG), euhydration was set at USG≤1.020. Fluid intake and thirst perception were evaluated by a questionnaire. The sample mean for USG was 1.021±0.008, 56% of players were dehydrated. Reported daily fluid intake was significantly (p<0.001, d=0.95, large effect) higher in EU compared to DE players. Daily fluid intake negatively correlated with USG (rS=-0.46, p<0.001, medium effect). The fluid intake perception score was significantly (p=0.005, d=0.54, medium effect) better in EU compared to DE players. Reported intake perception scores negatively correlated with USG (rS=-0.32, p<0.001, medium effect). However, there was no correlation (rS=-0.09, p=0.34, trivial effect) between thirst perception scores and USG. Thirst perception scores were not significantly different between EU and DE players (p=0.35, d=0.18, trivial effect). Our results indicated that self-assessment of both daily fluid intake and perceived fluid intake matched with objective hydration status, while self-assessment of thirst perception was not an appropriate indicator of hydration status in elite soccer players.



#3 Influence of crowd size on home advantage in the Japanese football league

Reference: Front Sports Act Living. 2022 Sep 9;4:927774. doi: 10.3389/fspor.2022.927774. eCollection 2022.

Authors: Ryota Nomura

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Summary: This study aimed to investigate the influence of crowd size on home advantage (HA). Data of the 2019 and 2020 seasons of the J1 League (Japan Professional Football's First Division League) were analyzed. Matches during the 2019 season were played under regular conditions, while there was low stadium occupancy during the 2020 season to prevent the spread of COVID-19. Regarding average points won, HA disappeared. By using multiple group structural equation modeling, it was examined the routes of influence via which a reduction in crowd size influenced HA. The results indicated that the influence from the crowd size to the referee's decisions disappeared during the 2020 season. However, the factors including the referee's decisions have lower effects on the outcome factor. Hence, no dominant route was detected in the present study.



#4 Repeat Anterior Cruciate Ligament Injury and Return to Sport in Australian Soccer Players After Anterior Cruciate Ligament Reconstruction With Hamstring Tendon Autograft

Reference: Am J Sports Med. 2022 Oct 3;3635465221125467. doi: 10.1177/03635465221125467.

Authors: Jonathan R Manara, Lucy J Salmon, Faisal M Kilani, Gerardo Zelaya de Camino, Claire Monk, Keran Sundaraj, Leo A Pinczewski, Justin P Roe

Summary: Soccer is the most commonly played team sport in the world and a high-risk sport for anterior cruciate ligament (ACL) injury and subsequent ACL reconstruction (ACLR). The aim was to assess the rate of further ACL injury in patients who have undergone ACLR with hamstring tendon autograft after soccer injuries in Australia and to determine factors associated with repeat ACL injury and return to soccer. From a prospectively collected database, a series of 1000 consecutive ACLRs using hamstring autografts performed in soccer players were identified. Patients were surveyed at a minimum 5 years after reconstruction, including details of further ACL injuries to either knee, return to soccer or other sports, and psychological readiness per the Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) scale. Of the 862 participants reviewed, ACL graft rupture occurred in 85 (10%) and contralateral ACL rupture in 68 (8%) within 5 years after the reconstruction. The 5-year ACL graft survivorship was 94% for females and 88% for males. The survivorship of the contralateral ACL was 92% for males and 90% for females. When compared with those aged >25 years, the odds of ACL graft rupture was increased by 4 to 5 times in those aged 19 to 25 years and 3 to 7 times in those ≤18 years. Further ACL injury to the graft or contralateral knee occurred in 44% of males aged ≤18 years. Risk factors for further ACL injury were younger age at time of surgery, male sex, and return to soccer. Graft diameter did not influence ACL graft rupture rates, and 70% of patients returned to soccer after ACLR. The mean ACL-RSI score was 59, and patients who reported more fear of reinjury on this scale were less likely to have returned to soccer. The prevalence of ACL graft rupture (10%) and contralateral ACL rupture (8%) was near equivalent over 5 years in this large cohort of mostly recreational Australian soccer players. ACLR with hamstring autograft is a reliable procedure, allowing 70% of patients to return to soccer in this high-risk population. Risk factors for further ACL injury are progressively younger age at time of surgery, male sex, and return to soccer. Graft diameter was not a factor in ACL graft rupture, indicating that other factors, particularly age, are of primary importance.



#5 Contextual variables affect peak running performance in elite soccer players: A brief report

Reference: Front Sports Act Living. 2022 Sep 16;4:966146. doi: 10.3389/fspor.2022.966146. eCollection 2022.

Authors: Diêgo Augusto, João Brito, Rodrigo Aquino, Dailson Paulucio, Pedro Figueiredo, Bruno Luiz Souza Bedo, Deborah Touguinhó, Fabrício Vasconcellos

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Summary: The current brief research report aimed to investigate the influence of contextual variables on peak running performance in male elite soccer players. We analyzed 29 matches of an elite soccer team during the Brazilian Serie A 2019. Twenty players were tracked using GPS units. Peak physical performance was determined using moving average running values with different time windows (1, 3, and 5-min periods). The variables analyzed were total distance covered, total distance covered in high-intensity running (≥19.8 km·h-1), and the distance in accelerations (≥2 m·s-2) and decelerations ( ≤-2 m·s-2). Four contextual variables were considered: 1) positional status; 2) match location; 3) match outcome; and 4) match status. Central defenders showed a lower 1-min peak total distance in relation to all other positions (p = 0.001-0.03). Peak physical performance was higher in away matches for high-intensity running, acceleration, and deceleration (p = 0.01-0.03). In matches that ended in losses, peak values for high-intensity running and acceleration were higher compared to draws and wins (p = 0.01-0.04). Regarding the match status, higher values were observed in draws than wins and losses (p = 0.01). Peak running performance vary according to contextual variables of the match in male elite soccer players. Positional differences were found for peak periods, and physical performance was higher in away matches.



#6 Daily and weekly external loads in the microcycle: Characterization and comparison between playing positions on amateur soccer

Reference: Front Sports Act Living. 2022 Sep 15;4:943367. doi: 10.3389/fspor.2022.943367. eCollection 2022.

Authors: Mauro Miguel, Alberto Cortez, Felix Romero, Nuno Loureiro, Javier García-Rubio, Sergio José Ibáñez

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Summary: Ensuring adequate levels of training and recovery to maximize player performance is critical; however, there are methodological challenges in designing a periodized training program for soccer teams. This study aims to describe and characterize the daily and weekly external load in an amateur soccer team and based on the weighting factors determined by the match reference, compare the external loads between playing positions. Twenty-four amateur soccer players (22.3 ± 1.7 years) were monitored using a global positioning system. Data collected comprises 19 competitive microcycles with a standard structure composed of 3 training sessions (matchday-5, matchday-3, and matchday-2) and one match. Match-reference values were calculated as the mean of the five best values recorded during official matches. The results show, on matchday-5 session, the existence of significant differences between playing positions to relative total distance covered (p = 0.050), relative sprint distance (p = 0.001), relative moderate-intensity accelerations (p < 0.001), relative high-intensity accelerations (p = 0.003), relative moderate-intensity decelerations (p < 0.001), and relative high-intensity decelerations (p = 0.017). On matchday-3 session, there are significant differences to relative very high-speed running distance (p = 0.017) and relative moderate-intensity decelerations (p = 0.014). On matchday-2 session, there are significant differences to relative high-speed running distance (p = 0.025), relative very high-speed running distance (p = 0.008), and relative moderate-intensity decelerations (p < 0.001). Weekly significant differences are observed between the playing positions to relative moderate-intensity accelerations (p = 0.002), relative high-intensity accelerations (p < 0.001), and relative moderate-intensity decelerations (p < 0.001). The weekly load is characterized by a greater weighting on accelerations and decelerations, compared to distances at very-high speed and sprint. The training loads must respect a standard training model that contemplates the individualization of the physical demands of the match, for each playing position, as for each individual.



#7 Obturator Internus Bursitis Mimicking Groin Pain in a Football Player: A Case Report

Reference: J Orthop Case Rep. 2022 Feb;12(2):106-111. doi: 10.13107/jocr.2022.v12.i02.2688.

Authors: Omkar Sadigale, Anjali Tiwari, Madhankumar Ramanathan, Himanshu Choudhury, Farokh Wadia, Vaibhav Bagaria

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Summary: Traumatic groin pain (GP) is frequently the result of acute trauma, often an indirect muscle injury. The most affected muscles in traumatic GP are the rectus abdominis, adductors, and iliopsoas. The obturator internus bursitis as a cause of GP is very rare. The present case describes a rare indirect injury of obturator internus bursitis in a 22-year-old male football player who reported GP that used to worsen with sprinting and change in directions. The pain was relieved with rest and sprinting at 80% capacity. The patient had been diagnosed clinically and on magnetic resonance imaging (MRI) as a case of obturator internus insertional tendinopathy with bursitis. His symptoms resolved after ultrasound-guided injection in the inflamed tendon sheath at its insertion point. After 2 years, the patient was followed up with a triumphant return to professional football with no recurrence and a good prognosis in a relatively short recovery time. Clinical diagnosis of obturator injuries is often tricky. GP not responding to conservative management presents a unique challenge to the physician and the rehabilitation team. MRI must follow the radiological investigations and ultrasound if the reports were inconclusive of the diagnosis. In the present case study, the usual causes of such pain (osteitis pubis, and adductor muscle strains/tendinosis) were ruled out, and a specific unique condition was diagnosed with the help of the MRI.



#8 Assessing the Sprint Force-Velocity Profile in International Football Players with Cerebral Palsy: Validity, Reliability and Sport Class' Profiles

Reference: J Hum Kinet. 2022 Apr 26;82:253-262. doi: 10.2478/hukin-2022-0065. eCollection 2022 Apr.

Authors: Iván Peña-González, Alejandro Javaloyes, José Manuel Sarabia, Manuel Moya-Ramón

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Summary: This study assessed and described the Sprint Force-velocity (SFv) profile, and its validity and reliability in international cerebral palsy (CP) football players. Twenty international male CP football players (age: 26.9±7.4) performed a 30-m sprint, a vertical jump (CMJ), a change of direction (MAT), a dribbling and an intermittent endurance (Yo-YoIR1) test. The SFv profile and physical performance variables were shown according to the players' sport class with the estimation of the effect sizes between classes. The SFv showed high reliability (ICC=0.77 to 0.99; SEM=0.89 to 8.66%). Validity for the SFv was provided by its positive correlation with the players' sport class (r=0.53 to 0.75; p=.02 to <.01) and the rest of the physical performance tests (r=0.45 to 0.99; p=.04 to <.01). The RFmax was the main SFv profile variable that explained players' performance in the rest of the tests (β=0.77 to 1.0; p<.05; R2=0.59 to 0.99). The SFv profile seems to be an efficient test to assess international CP football players' physical performance. This provides information about the players' individual sprint mechanical characteristics and their sprint strengths and weaknesses, allowing coaches and conditioning trainers to individualize their training interventions to optimize sprint performance.



#9 Service quality in football tourism: an evaluation model based on online reviews and data envelopment analysis with linguistic distribution assessments

Reference: Ann Oper Res. 2022 Sep 22;1-34. doi: 10.1007/s10479-022-04992-x. Online ahead of print.

Authors: Adjei Peter Darko, Decui Liang, Yinrunjie Zhang, Agbodah Kobina

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Summary: The emergence of sports tourism has compelled sports managers to rethink the management and improvement of sports facilities. Through service quality analysis, sports managers can identify the strengths and weaknesses of their activities for possible advancement. Hence, this study aims to develop a decision support model based on integrating online reviews and data envelopment analysis to measure the degree of tourist satisfaction and provide benchmarking goals for service improvement. The proposed model employs text mining techniques to discover service quality attributes from text reviews. According to the discovered service quality attributes, we conduct sentiment analysis to reveal the sentiment polarities of the text reviews. Then, we refine the polarities and ratings of online reviews into linguistic distribution assessments. Furthermore, we develop a linguistic distribution output-oriented non-discretionary bestpoint slack-based measure (BP-SBM) to compute the degree of tourist satisfaction and benchmarking goals. The linguistic distribution output-oriented non-discretionary BP-SBM can handle both positive and negative data values, thus overcoming the flaws of the traditional model. Meanwhile, the proposed decision support model investigates how the service-quality attributes interact to provide improvement pathways for an underperforming stadium based on association rule mining. We test the applicability of the proposed decision support model on some Elite stadia in Europe.



#10 Evidence-Based Recovery in Soccer - Low-Effort Approaches for Practitioners

Reference: J Hum Kinet. 2022 Apr 26;82:75-99. doi: 10.2478/hukin-2022-0082. eCollection 2022 Apr.

Authors: Nils Haller, Erik Hübler, Thomas Stöggl, Perikles Simon

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Summary: Strategies to improve recovery are widely used among soccer players at both amateur and professional levels. Sometimes, however, recovery strategies are ineffective, improperly timed or even harmful to players. This highlights the need to educate practitioners and athletes about the scientific evidence of recovery strategies as well as to provide practical approaches to address this issue. Therefore, recent surveys among soccer athletes and practitioners were reviewed to identify the recovery modalities currently in use. Each strategy was then outlined with its rationale, its physiological mechanisms and the scientific evidence followed by practical approaches to implement the modality. For each intervention, practical and particularly low-effort strategies are provided to ensure that practitioners at all levels are able to implement them. We identified numerous interventions regularly used in soccer, i.e., sleep, rehydration, nutrition, psychological recovery, active recovery, foam-rolling/massage, stretching, cold-water immersion, and compression garments. Nutrition and rehydration were classified with the best evidence, while cold-water immersion, compression garments, foam-rolling/massage and sleep were rated with moderate evidence to enhance recovery. The remaining strategies (active recovery, psychological recovery, stretching) should be applied on an individual basis due to weak evidence observed. Finally, a guide is provided, helping practitioners to decide which intervention to implement. Here, practitioners should rely on the evidence, but also on their own experience and preference of the players.



#11 Influence of Tactical Behaviour on Running Performance in The Three Most Successful Soccer Teams During the Competitive Season of The Spanish First Division

Reference: J Hum Kinet. 2022 Apr 26;82:135-144. doi: 10.2478/hukin-2022-0040. eCollection 2022 Apr.

Authors: Jose Asian-Clemente, Luis Suarez-Arrones, Bernardo Requena, Alfredo Santalla

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Summary: The purpose of this study was to analyze the influence of tactical behavior on physical performance of the three best Spanish soccer teams. Team 1 employed a 1-4-4-2 formation with compact defence and direct attacks, Team 2 employed an indirect style of play with a 1-4-3-3 formation and Team 3 used a 1-4-3-3 formation with elaborate attacks and strong counter-attacks. 816 individual situations of 54 professional soccer players categorized as fullbacks (FB), central defenders (CD), central midfielders (MF), wide midfielders (WM), and strikers (S) were included in the analysis. Their performance was examined with a player-tracking system. The analyzed variables included total distance covered, distance covered above 14, 21 and 24 km·h-1, as well as distance covered in possession of the ball and without possession of the ball. Team 2 covered a substantially lower distance >14 km·h-1 than Team 1 and substantially lower distances >14, >21, and >25km·h-1 than Team 3. No differences in running activity were found between Teams 1 and 3. However, there were substantial differences between the specific positions of the three teams. CD in Team 1 covered the lowest distance by a substantial margin in almost all variables analysed, whereas MF travelled substantially greater distances than did other positions. WM in Team 1 covered the greatest distance >18 and >21km·h- 1, while S in Team 2 had the lowest distance covered in almost all the variables, and FB in Team 3 showed the lowest total distance covered and distance covered >14km·h-1. WM in Team 2 had the greatest distance covered in possession, while S in Team 3 had the greatest distance covered out of possession. The results indicate that different team formations and associated tactical demands have a significant influence on running performance.



#12 Hip adduction and abduction strength in youth male soccer and basketball players with and without groin pain in the past year

Reference: PLoS One. 2022 Oct 5;17(10):e0275650. doi: 10.1371/journal.pone.0275650. eCollection 2022.

Authors: Jan Marušič, Nejc Šarabon

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Summary: The objectives of this study were to 1) assess the differences between youth soccer and basketball players with and without past year groin pain (GP) in hip adduction and abduction strength and several training characteristics (age at the start of regular training, weekly training frequency, warm-up and training duration, use of stretching and/or stabilisation exercises during warm-up, use of resistance training); 2) present strength reference values for youth soccer and basketball players. 227 players participated (age 16.9 ± 1.4 years; height 184.2 ± 8.5 cm; mass 75.5 ± 11.9 kg). Hip adduction and abduction strength was measured in supine position (hip, knee and ankle in neutral position) using a MuscleBoard dynamometer. Interlimb asymmetries and hip adduction:abduction ratios were calculated. Past year GP and training characteristics were assessed with a retrospective questionnaire. 11.9% of players reported past year GP (16.9% in soccer and 6.4% in basketball). The only significant difference between the past year GP and the control groups was found in the age of the players at the start of regular training (7.2 ± 1.8 years for the GP group vs. 8.5 ± 2.6 years for the control group). Additionally, soccer players without past year GP have significantly higher hip adduction strength (1.1 ± 0.2 Nm/kg vs. 1.0 ± 0.2 Nm/kg) and adduction:abduction strength ratio (1.10 ± 0.18 vs. 1.03 ± 0.16) compared to basketball players. Our results show that hip adduction and abduction strength, interlimb asymmetry and hip adduction:abduction ratio do not differentiate between players with and without past year GP (p = 0.29-0.90), which means that their adduction or abduction strength can be analysed regardless of the GP presence in the past year. Additionally, players with past year GP started regularly training at significantly lower age, which could indicate the problematic nature of early/premature sports specialisation.



#13 Soccer-related injuries pre- and post-COVID-19 lockdown in Saudi Arabia: an epidemiological study

Reference: J Sports Med Phys Fitness. 2022 Oct 7.  doi: 10.23736/S0022-4707.22.14073-9. Online ahead of print.

Authors: Wesam S Al Attar, Alaa A Khushhal

Summary: Soccer predisposes players to injuries because it involves running, jumping, and interactions between players; players must maintain fitness through training and matches. Coronavirus disease (COVID-19) caused a global lockdown, and the ministry of sports suspended all sports activities, forcing players to train indoors. This study aimed to determine the number and nature of soccer injuries per thousand hours of exposure pre and post the COVID-19 lockdown in Saudi Arabia. In total, 45 soccer teams (630 players) competing in the amateur leagues were followed for two seasons (pre- and post-COVID-19 lockdown). The medical staff of the participating teams was requested to report all new injuries during matches and training. Exposure during all matches and training and number of overall, initial, recurrent, severity, and types of injuries reported pre- and post-COVID lockdown were recorded. A total of 43 injuries were reported pre-COVID-19 lockdown in 50130 h of exposure (0.86 injuries/1000 exposure hours). A total of 91 injuries were reported post-COVID-19 lockdown in 47622 hours of exposure (1.91 injuries/1000 exposure hours). The injury risk ratio was 0.45 (0.31 to 0. 65; P = 0.0001), suggesting that the injuries increased by 55% post-COVID-19 lockdown. The study results indicated that the COVID-19 lockdown influenced soccer-related injuries, as the overall number of soccer injuries increased because of the COVID-19 lockdown.



#14 Comparison of external load indicators between official matches and sport-specific training in semi-professional soccer players: focus on intensity and strength

Reference: J Sports Med Phys Fitness. 2022 Oct 7. doi: 10.23736/S0022-4707.22.14189-7. Online ahead of print.

Authors: Guglielmo Pillitteri, Valerio Giustino, Giuseppe Messina, Marco Petrucci, Alessio Rossi, Marianna Bellafiore, Angelo Iovane, Ewan Thomas, Antonino Bianco, Antonio Palma, Giuseppe Battaglia

Summary: The aim of this study was to investigate any differences in External Load indicators (ELi) between Official Matches (OM) and sport-specific tasks in semi-professional soccer players. 1932 observations among 28 semi-professional soccer players (FC Palermo, Italy, age: 25±6 years, height: 183±6 cm, weight: 75.2±7 kg) were collected through GPS devices (Qstarz BT-Q1000EX, 10 Hz) and the related software (LaGalaColli V: during the season 2019-2020. Participants were monitored during OM, Friendly Matches (FM), Small Sided Games (SSG), and Match-Based Exercises (MBE), considering the percentage of intense accelerations (%int acc), percentage of intense decelerations (%int dec), and Passive Recovery time /min (PrT/m) as Eli. We detected the highest mean value for PrT/m in OM and the lowest in MBE and SSG (18.36±4.38 and 13.4±5.26 and 13.4±4.29 (s/min), respectively). The lowest mean values of %int acc and %int dec were found in OM and the highest in SSG (8.64±1.52 vs 13.02±3.14 and 9.25±1.56 vs 15.68±3.14, for %int acc and %int dec, respectively). Significant differences between the four tasks for all the ELi considered (p<0.001). The posthoc pairwise comparisons revealed significant differences for all the ELi between all tasks (p<0.001) except for the %int acc between MBE vs FM (p=0.003). No significant difference was found in PrT/m between MBE vs FM and SSG vs FM. ELi are in accordance with the performance model by achieving better values in training than OM, suggesting the fundamental role of GPS for monitoring external load in soccer.



#15 The Dose-Response Relationship Between Training-Load Measures and Changes in Force-Time Components During a Countermovement Jump in Male Academy Soccer Players

Reference: Int J Sports Physiol Perform. 2022 Oct 11;1-8. doi: 10.1123/ijspp.2022-0107. Online ahead of print.

Authors: Matthew Ellis, Tony Myers, Richard Taylor, Rhys Morris, Ibrahim Akubat

Summary: The aim was to manage physical performance in soccer, practitioners monitor the training load (TL) and the resulting fatigue. A method frequently used to assess performance is the countermovement jump (CMJ). However, the efficacy of CMJ to detect fatigue from soccer matches and training remains uncertain, as does the relationship between TL and change in CMJ performance. The aims of the present study were 2-fold. One was to observe the changes of CMJ force-time components and jump height (JH). The second was to examine dose-response relationships between TL measures and CMJ over a 6-week preseason. Twelve male academy soccer players (17 [1] y, 71.2 [5.6] kg, and 178 [5.8] cm) were recruited. Daily changes in CMJ were assessed against baseline scores established before preseason training, along with internal and external TL measures. A series of Bayesian random intercept models were fitted to determine probability of change above/below zero and greater than the coefficient of variation established at baseline. Jumps were categorized into match day minus (MD-) categories where the higher number indicated more time from a competitive match. JH was lowest on MD - 3 (28 cm) and highest on MD - 4 (34.6 cm), with the probability of change from baseline coefficient of variation highly uncertain (41% and 61%, respectively). Changes to force-time components were more likely on MD - 3 (21%-99%), which provided less uncertainty than JH. Bayes R2 ranged from .22 to .57 between TL measures and all CMJ parameters.



#16 The evaluation of playing styles integrating with contextual variables in professional soccer

Reference: Front Psychol. 2022 Sep 23;13:1002566. doi: 10.3389/fpsyg.2022.1002566. eCollection 2022.

Authors: Lingfeng Kong, Tianbo Zhang, Changjing Zhou, Miguel-Angel Gomez, Yue Hu, Shaoliang Zhang

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Summary: Playing styles play a key role in winning soccer matches, but the technical and physical styles of play between home and away match considering team quality in the Chinese Soccer Super League (CSL) remain unclear. The aim of this study was to explore the technical and physical styles of play between home and away matches integrating with team quality in the CSL. The study sample consists of 480 performance records from 240 matches during the 2019 competitive season in the CSL. These match events were collected using a semi-automatic computerized video tracking system, Amisco Pro®. A k-means cluster analysis was used to evaluate team quality and then using principal component analysis (PCA) to identify the playing styles between home and away matches according to team quality. Differences between home and away matches in terms of playing styles were analyzed using a linear mixed model. Our study found that PC1 presented a positive correlation with physical-related variables such as HIRD, HIRE, HSRD, and HSRE while PC2 was positively associated with the passing-related variables such as Pass, FPass, PassAcc, and FPAcc. Therefore, PC1 typically represents intense-play styles while PC2 represents possession-play styles at home and away matches, respectively. In addition, strong teams preferred to utilize intensity play whereas medium and weak teams utilized possession play whenever playing at home or away matches. Furthermore, the first five teams in the final overall ranking in the CSL presented a compensated technical-physical playing style whereas the last five teams showed inferior performance in terms of intensity and possession play. Intensity or possession play was associated with the final overall ranking in the CSL, and playing styles that combine these two factors could be more liable to win the competition. Our study provides a detailed explanation for the impact of playing styles on match performances whereby coaches can adjust and combine different playing styles for ultimate success.



#17 Repetitive soccer heading adversely impacts short-term learning among adult women

Reference: J Sci Med Sport. 2022 Aug 26;S1440-2440(22)00222-5. doi: 10.1016/j.jsams.2022.08.011.

Authors: Kenny Ye, Roman Fleysher, Richard B Lipton, Molly E Zimmerman, Walter F Stewart, Martin J Sliwinski, Mimi Kim, Michael L Lipton

Summary: The purpose was to determine the impact of 12-month heading exposure on short-term learning. A total of 105 active amateur soccer players, 45 women and 60 men, were administered an EMA-based test of working memory, a version of the two-back, once daily for 14 days. Heading exposure of the participants was assessed using "HeadCount", a validated structured questionnaire at the baseline visits. The short-term rate of learning of each individual is quantified by first fitting a quadratic model to the daily performance on the two-back test over a two-week period, then taking the instantaneous rate of the quadratic function at the 7th test. A linear regression model was used to test the association of heading exposure with rates of learning, including age, sex, years of education and history of concussion as covariates, as well as variables describing soccer play and heading within the two-week period. Sensitivity analyses were performed using different methods for quantifying the learning effects and different transformations on 12-month heading exposure. Greater 12-month heading was associated with lower rates of learning among women (p = 0.008) but not among men (p = 0.74). We have identified evidence for an adverse, albeit subclinical, effect of soccer heading on brain function among young adult players, which selectively affects women in our sample.



#18 The soccer season: performance variations and evolutionary trends

Reference: PeerJ. 2022 Oct 5;10:e14082. doi: 10.7717/peerj.14082. eCollection 2022.

Author: Joao Renato Silva

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Summary: The physiological demands of soccer challenge the entire spectrum of the response capacity of the biological systems and fitness requirements of the players. In this review we examined variations and evolutionary trends in body composition, neuromuscular and endurance-related parameters, as well as in game-related physical parameters of professional players. Further, we explore aspects relevant for training monitoring and we reference how different training stimulus and situational variables (e.g., competition exposure) affect the physiological and performance parameters of players. Generally, improvements of small magnitude in non- (non-CMJ) and countermovement-based jumps (CMJBased) and in the sprint acceleration (ACCPhase) and maximal velocity phase (MVPhase) are observed from start of preparation phase (PPS) to beginning of competition phase (BCP). A greater magnitude of increases is observed in physiological and endurance performance measures within this period; moderate magnitude in sub-maximal intensity exercise (velocity at fixed blood lactate concentrations; V2-4mmol/l) and large magnitude in VO2max, maximal aerobic speed (MAS) and intense intermittent exercise performance (IE). In the middle of competition phase (MCP), small (CMJBased and ACCPhase), moderate (non-CMJ; MVPhase; VO2max; sub-maximal exercise) and large (MAS and IE) improvements were observed compared to PPS. In the end of competition period (ECP), CMJBased and MVPhase improve to a small extent with non-CMJ, and ACCPhase, VO2max, MAS, sub-maximal intensity exercise and IE revealing moderate increments compared to PPS. Although less investigated, there are generally observed alterations of trivial magnitude in neuromuscular and endurance-related parameters between in-season assessments; only substantial alterations are examined for IE and sub-maximal exercise performance (decrease and increase of small magnitude, respectively) from BCP to MCP and in VO2max and IE (decrements of small magnitude) from MCP to ECP. Match performance may vary during the season. Although, the variability between studies is clear for TD, VHSR and sprint, all the studies observed substantial increments in HSR between MCP and ECP. Finally, studies examining evolutionary trends by means of exercise and competition performance measures suggests of a heightened importance of neuromuscular factors. In conclusion, during the preseason players "recover" body composition profile and neuromuscular and endurance competitive capacity. Within in-season, and more robustly towards ECP, alterations in neuromuscular performance seem to be force-velocity dependent, and in some cases, physiological determinants and endurance performance may be compromised when considering other in-season moments. Importantly, there is a substantial variability in team responses that can be observed during in-season. Consequently, this informs on the need to both provide a regular training stimulus and adequate monitorization throughout the season.






Can high-intensity interval training and small-sided games be effective for improving physical fitness after detraining?

The aim of this study was two-fold: (i) analyze the within-group physical fitness adaptations promoted by a detraining period (4 weeks) followed by an intervention period (4 weeks) using small-sided games (SSGs) or running-based high intensity interval training (HIIT); and (ii) analyze the between-group differences aiming to identify the effectiveness of each training intervention on the physical fitness of youth male soccer players.





The Influence of In-Game Changes of Tactical Formation in Professional Soccer

This study aimed to examine the effects of in-game changes in tactical formation on match performance and to analyze coach-specific differences.





Latest research in football - week 37 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 T-pattern analysis of offensive and defensive actions of youth football goalkeepers

Reference: Front Psychol. 2022 Sep 2;13:957858. doi: 10.3389/fpsyg.2022.957858. eCollection 2022.

Authors: Fernando Santos, João Santos, Mário Espada, Cátia Ferreira, Paulo Sousa, Valter Pinheiro

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Summary: Nowadays, football goalkeepers (GKs) play an important role in the team's organization, namely, considering the offensive and defensive processes. The purpose of our investigation focuses on the notational and T-pattern analysis of the offensive and defensive actions of elite young football GKs. The participating GKs (n = 3, mean age of 16.6 years) presented 8 years of experience in the specific position, were internationally selected for the national team of Portugal, and competed in the national U-17 championship of Portugal. Thirty football matches were observed. The observational sample consisted of defensive actions (n = 225) and offensive actions (n = 296). Two observational instruments were used to codify the actions: the observation system of defensive technical-tactical actions of GKs and the observation system of offensive technical-tactical actions of GKs. Both instruments underwent a validation process, and inter- and intra-observer reliability was tested. The codification of the actions was performed with the LINCE program, and later the data were exported to Microsoft Excel and THEME 5.0. The notational data were analyzed in SPSS, and T-pattern detection analysis was performed in THEME 5.0. The predominant actions of young observed GKs were fundamentally goal defense and participation in the team's offensive process construction through actions performed with the foot and hand. The analysis of T-patterns allowed to identify T-pattern actions in the defensive actions of goal defense and exit of the goal, as well as related to the defensive set pieces. In the offensive process, the analysis of T-patterns reinforced the participation of the GK in the team's first phase of construction and in the execution of goal kicks and actions that start as a result of the actions of the opponent. The GK's defensive actions are mostly focused on the objective of goal defense and offensive actions with the hands and feet are important for their participation in positional attack construction. Our study contributes to a better knowledge of the GK's actions in the competition and is relevant to be considered by the specific position coaches in the training process organization.



#2 Weekly Training Load across a Standard Microcycle in a Sub-Elite Youth Football Academy: A Comparison between Starters and Non-Starters

Reference: Int J Environ Res Public Health. 2022 Sep 15;19(18):11611. doi: 10.3390/ijerph191811611.

Authors: José E Teixeira, Luís Branquinho, Ricardo Ferraz, Miguel Leal, António J Silva, Tiago M Barbosa, António M Monteiro, Pedro Forte

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Summary: Compensatory training sessions have been highlighted as useful strategies to solve the differential weekly training load between the players' starting status. However, the influence of the players' starting status is still understudied in sub-elite youth football. Thus, the aim of this study was to compare the weekly training load on a standard microcycle in starters and non-starters of a sub-elite youth football academy. The weekly training load of 60 young sub-elite football players was monitored during a 6-week period using an 18 Hz global positioning system (GPS), 1 Hz telemetry heart rate, rating of perceived exertion (RPE), and total quality recovery (TQR). The total distance (TD) covered presented a significant difference between starters and non-starters with a moderate effect (t = -2.38, Δ = -428.03 m, p = 0.018, d = 0.26). Training volume was higher in non-starters than in starter players (TDStarters = 5105.53 ± 1684.22 vs. TDNon-starters = 5533.56 ± 1549.26 m). Significant interactive effects were found between a player's starting status, playing time, and session duration in overall training load variables for within (F = 140.46; η2 = 0.85; p &lt; 0.001) and between-subjects (F = 11.63 to 160.70; η2 = 0.05 to 0.76; p &lt; 0.001). The player's starting status seems to only influence the training volume in sub-elite youth football, unless one considers the covariance of the playing time and session duration. Consequently, coaches should prioritize complementary training to equalize training volume and emphasize similar practice opportunities for non-starters. Future studies should evaluate the gap between training and match load, measuring the impact of recovery and compensatory sessions.



#3 The Effect of Selected Polymorphisms of the ACTN3, ACE, HIF1A and PPARA Genes on the Immediate Supercompensation Training Effect of Elite Slovak Endurance Runners and Football Players

Reference: Genes (Basel). 2022 Aug 25;13(9):1525. doi: 10.3390/genes13091525.

Authors: Dávid Végh, Katarína Reichwalderová, Miroslava Slaninová, Miroslav Vavák

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Summary: We aimed to evaluate the effect of selected polymorphisms of the ACTN3, ACE, HIF1A and PPARA genes on the immediate supercompensation training effect of elite Slovak endurance runners and football players compared with a sedentary control group. Adaptation effect levels were evaluated by 10 s continuous vertical jump test parameters measured by Optojump. Genetic polymorphisms were determined by PCR and Sanger sequencing. We found significant differences in the effect of PPARA genotypes in the experimental group. C allele genotypes represented an advantage in immediate supercompensation (p &lt; 0.05). We observed a significant combined effect of multiple genes on immediate supercompensation (p &lt; 0.05): the RR genotype of the ACTN3 gene, the ID genotype of the ACE gene, the Pro/Pro genotype of HIF1A, and the GC and GG genotypes of PPARA genes. In the control group, we found a significant effect (p &lt; 0.05) on immediate supercompensation of the II genotype of the ACE gene and the Pro/Ser genotype of the HIF1A gene. We found significant differences in genotype frequency of ACE (p &lt; 0.01) and PPARA (p &lt; 0.001) genes. We confirmed that individual genetic polymorphisms of ACTN3, ACE, HIF1A and PPARA genes have a different effect on the level of immediate supercompensation of the lower limbs depending on the training adaptation of the probands and the combination of genotypes.



#4 Soccer and Risk of Cardiovascular Events

Reference: Cardiol Res. 2022 Aug;13(4):218-227. doi: 10.14740/cr1398. Epub 2022 Aug 15.

Authors: Juan Enrique Puche

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Summary: Physical and emotional stress have been associated with an increased incidence of acute coronary syndrome (ACS). Sporting events such as soccer matches can cause spectators to experience cardiovascular events. The objective of the present study was to determine whether an association of this type existed during a Spanish league competition. We recorded data from patients who were admitted with ACS during 2018 - 2020. Patients were divided into two groups: those who were admitted on the day the local team played and those who were admitted on nonmatch days. We determined various cardiovascular risk factors, including the degree of hostility and anxiety. Away wins reduced the number of admissions with ACS by 30%, whereas a local loss increased hospitalizations by more than 30%. The profile of patient admitted on match days was a > 65 years old man, smoker (current or past), obese, with worse control of his hypertension, diabetes, and dyslipidemia, poor pharmacological adherence and high anxiety and hostility scores. A loss by the local team increases the number of admissions with ACS in males with a high burden of cardiovascular risk factors. Primary prevention measures should be taken to reduce the frequency of these events.



#5 Video analysis of Achilles tendon rupture in male professional football (soccer) players: injury mechanisms, patterns and biomechanics

Reference: BMJ Open Sport Exerc Med. 2022 Sep 22;8(3):e001419. doi: 10.1136/bmjsem-2022-001419. eCollection 2022.

Authors: Francesco Della Villa, Matthew Buckthorpe, Fillippo Tosarelli, Matteo Zago, Stefano Zaffagnini, Alberto Grassi

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Summary: Achilles tendon rupture (ATR), while rare in football, is a severe career-threatening injury associated with long-layoff times. To date, no study has documented ATR's mechanism in professional football players. The aim was to describe the mechanisms, situational patterns and gross biomechanics (kinematics) of ATR injuries in professional male football players. Eighty-six (n=86) consecutive ATR injuries in professional football players during official matches were identified. Sixty (70%) injury videos were identified for mechanism and situational pattern, with biomechanical analysis feasible in 42 cases. Three independent reviewers evaluated the injury videos. Distribution of ATR during the season, the match play and on the field were also reported. Fifty (n=50, 83%) injuries were classified as non-contact and 10 (17%) as indirect contact. ATRs are injuries occurring during accelerations; three main situational patterns were identified: (1) forward acceleration from standing (n=25, 42%); (2) cross-over cutting (n=15, 25%) and (3) vertical jumping (n=11, 18%). Biomechanically, ATR injuries were consistent with a multiplanar loading at the injury frame consisting of a slightly flexed trunk (15.5°), extended hip (-19.5°), early flexed knee (22.5°) and end-range dorsiflexed (40°) ankle in the sagittal plane and foot pronation; 27 (45%) ATRs occurred in the first 30 min of effective match time. All ATRs in professional football were either non-contact (83%) or indirect contact (17%) injuries. The most common situational patterns were forward acceleration from standing, cross-over cutting and vertical jumping. Biomechanics was consistent and probably triggered by a multiplanar, although predominantly sagittal, loading of the injured Achilles tendon.



#6 Bio-banding in soccer: Past, present, and future

Reference: Ann Hum Biol. 2022 Sep 27;1-12. doi: 10.1080/03014460.2022.2129091. Online ahead of print.

Authors: Chris Towlson, Sean P Cumming

Summary: Maturity-related selection biases are engrained within professional academy soccer programmes. The process of grouping of children by biological maturity ("bio-banding"), rather than age is not new. However, practice of bio-banding is becoming increasingly popular with youth soccer development programmes where maturity-related differences in size and athleticism have been cited as key mechanisms behind the over-selection of early over late maturing players. However, the objectives of bio-banding require further clarity to avoid a disconnect between contemporary academic evidence and present and future practitioner practice. Therefore, the purpose of this commentary is to 1) provide a concise overview of the literature (to date), 2) identify possible applications of bio-banding to permit more informed decisions relating to the evaluation and management of young soccer players and (3) propose future directions for both research and applied practice.



#7 Head Impact Sensor Attachment and Data Transformation in a Youth Female Soccer Heading Drill

Reference: Conf Proc Int Res Counc Biomech Inj. 2020;2020:870-871.

Authors: Declan A Patton, Colin M Huber, Kristy B Arbogast

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#8 Physical Performance Indicators and Team Success in the German Soccer League

Reference: J Hum Kinet. 2022 Sep 8;83:257-265. doi: 10.2478/hukin-2022-0099. eCollection 2022 Aug.

Authors: Paweł Chmura, José M Oliva-Lozano, José M Muyor, Marcin Andrzejewski, Jan Chmura, Sławomir Czarniecki, Edward Kowalczuk, Andrzej Rokita, Marek Konefał

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Summary: The aims of this study were (1) to determine the match running performance required by different teams based on their final ranking position and (2) to analyze the association between match running performance variables and team success at the end of the season. A total of 1,224 match observations from professional soccer teams competing during two consecutive seasons in the German Bundesliga were analyzed. In addition, the final league ranking position and the total of points obtained by each team at the end of the season were registered for the analysis of the association between team success and match running performance. The main findings were that high ranked teams covered the greatest total distance with ball possession, sprinting distance with ball possession, and completed the greatest number of sprinting actions with ball possession and maximal velocity. Moreover, total distance covered with possession of the ball and maximal velocity were the most important variables to predict the total of points obtained at the end of the season. Specifically, the relative contribution of total distance covered with ball possession to the total of points obtained was greater than maximal velocity. Training programs for professional soccer players should be focused on improving the sprint capacity and running with possession of the ball (e.g., transitional tasks and small-sided games). Moreover, this has implications for injury prevention, physical, psychological, and technical-tactical training since today's soccer requires players to engage in repeated high-intensity actions, reach maximum speeds above 9 m/s, and develop technical-tactical coordination when running with the ball.



#9 Influence of physical and psychological stress on decision-making performance of soccer referees

Reference: J Sports Sci. 2022 Sep 29;1-10. doi: 10.1080/02640414.2022.2127516. Online ahead of print.

Authors: Alexandra Pizzera, Sylvain Laborde, Johannes Lahey, Patrick Wahl

Summary: Soccer referees have to make quick and accurate decisions while experiencing physical stress (i.e., fatigue) and psychological stress (i.e., pressure from the crowd). Researchers have examined the influence of physical and psychological stress on skilled referees' decision-making performance separately; however, referees usually experience both types of stress simultaneously. The aim of the study was to investigate the influence of both physical and psychological stress on skilled and less-skilled soccer referees' decision-making performance. To simulate the physical and psychological stress during a game, 25 referees were asked to make foul decisions while running on a treadmill and/or being exposed to auditory stress. Referees were more physically fatigued in the physical and psychologically stressed in the psychological stress condition. However, this only negatively influenced their decision-making performance in the video test during the submaximal physical stress condition, when compared to the resting condition. The results also indicate that the experienced referees learned to cope with fatigue and psychological stress regarding their cognitive processes. The effects seem to be differentially detrimental, depending on the league level of refereeing, but also whether physical and psychological stress are induced separately. The study protocol could help referees train in a simulated learning environment, besides on-field games.



#10 Predicting the in-game status in soccer with machine learning using spatiotemporal player tracking data

Reference: Sci Rep. 2022 Sep 29;12(1):16291. doi: 10.1038/s41598-022-19948-1.

Authors: Steffen Lang, Raphael Wild, Alexander Isenko, Daniel Link

Summary: An important structuring feature of a soccer match is the in-game status, whether a match is interrupted or in play. This is necessary to calculate performance indicators relative to the effective playing time or to find standard situations, ball actions, and other tactical structures in spatiotemporal data. Our study explores the extent to which the in-game status can be determined using time-continuous player positions. Therefore, to determine the in-game status we tested four established machine learning methods: logistic regression, decision trees, random forests, and AdaBoost. The models were trained and evaluated using spatiotemporal data and manually annotated in-game status of 102 matches in the German Bundesliga. Results show up to 92% accuracy in predicting the in-game status in previously unknown matches on frame level. The best performing method, AdaBoost, shows 81% precision for detecting stoppages (longer than 2 s). The absolute time shift error at the start was ≤ 2 s for 77% and 81% at the end for all correctly predicted stoppages. The mean error of the in-game total distance covered per player per match using the AdaBoost in-game status prediction was - 102 ± 273 m, which is 1.3% of the mean value of this performance indicator (7939 m). Conclusively, the prediction quality of our model is high enough to provide merit for performance diagnostics when teams have access to player positions (e.g., from GPS/LPM systems) but no human-annotated in-game status and/or ball position data, such as in amateur or youth soccer.



#11 Differences in Physical Match Performance and Injury Occurrence Before and After the COVID-19 Break in Professional European Soccer Leagues: A Systematic Review

Reference: Sports Med Open. 2022 Sep 30;8(1):121. doi: 10.1186/s40798-022-00505-z.

Authors: Maximiliane Thron, Peter Düking, Sascha Härtel, Alexander Woll, Stefan Altmann

Summary: Due to the COVID-19 pandemic, matches and soccer-specific training were suspended for several weeks, matches after resumption were congested, and substitutions per team and game increased from three to five. The aim of this review was to examine possible differences in physical match performance and injuries between before and after the COVID-19 induced break of matches and training in professional male European soccer leagues during the 2019/2020 season. A systematic search identified all scientifically peer-reviewed publications involving elite male soccer players competing in the European leagues which reported physical match performance variables such as total running distance and running distance at different speed zones and/or injury parameters pre- and post-COVID-19 induced break. In total, 11 articles were included, which were coming from German Bundesliga, Polish Ekstraklasa, Croatian HNL, Spanish La Liga, and Italian Serie A. In all studies investigating the German Bundesliga, most parameters of physical match performance remained unaffected (0.08 ≤ p ≤ 0.82; - 0.15 ≤ ES 0.15), while studies investigating the Polish Ekstraklasa (p ≤ 0.03; - 0.27 ≤ ES - 0.18), Croatian HNL (p ≤ 0.04; - 1.42 ≤ ES ≤ 1.44), Spanish La Liga (p ≤ 0.017; - 0.32 ≤ ES ≤ 5.5), and Italian Serie A (p ≤ 0.014; - 1.01 ≤ ES 0.24) showed a decrease in most parameters of physical match performance after the COVID-19 break. Injury rates were only investigated by studies targeting the German Bundesliga and Italian Serie A. In the majority of studies (3 out of 4 studies), there occurred no difference in injuries between pre- and post-COVID-19 break (p > 0.05; ES = N/A). Results indicate that Bundesliga teams maintained physical match performance during the 9-weeks break in matches and 3-weeks break in group training, whereas a longer match and group training interruption up to 15 weeks and 8 weeks, respectively, in the other leagues appeared to lead to a decreased physical match performance. Regarding injuries, we speculate that the increase in substitutions from 3 to 5 substitutions per game might prevent an increase in injury occurrence during matches. The underlying studies' results provide hints for possible upcoming unexpected interruptions with respect to optimal physical preparations for the resumption of matches and a congested schedule to maintain physical match performance, or for possible rule changes such as 5 instead of 3 substitutions to avoid physical overload during congested match schedules.



#12 External Workload Compared Between Competitive and Non-Competitive Matches for Professional Male Soccer Players

Reference: J Hum Kinet. 2022 Sep 8;83:175-184. doi: 10.2478/hukin-2022-0057. eCollection 2022 Aug.

Authors: Jose Asian-Clemente, Bermardo Requena, Adam Owen, Alfredo Santalla

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Summary: The purpose of this study was to compare the external load in competitive (official) and non-competitive matches (friendly, training and modified-sided games) in professional soccer players. Time-motion data for 10 elite male soccer players (age = 20.1 ± 2.1 years; body height = 178.8 ± 5.9; body mass = 71.4 ± 7.3; % body fat = 11.0 ± 1.1 and VO2max = 55.96 ± 3.3) from a professional Spanish first division team were recorded during official (n = 12), friendly (n = 7) and training (n = 6) matches and a 5 vs. 5 + goalkeepers modified-sided game (n = 3). GPS devices were used to monitor players' external loads: total distance covered, distance covered at different speeds (<13.9 km·h-1, >14, >18, >21 and >25 km·h-1), peak speed (km·h-1), and the number of accelerations and decelerations (1.5-2.5 m·s-2, 2.5-4 m·s-2 and 4-8 m·s-2). One-way analysis of variance of the magnitude-based inference was used to determine differences between matches. Data indicated that official matches scored statistically higher peak speeds (ES = 1.40-2.20). In modified-sided games more total distance was covered at <13.9 km·h-1 and >14 km·h-1 than in regular matches (ES = 0.72-2.21), but lower distances were covered at >21 km·h-1 and >25 km·h-1 than in official and friendly matches (ES = 0.51-2.53) and at >25 km·h-1 than in training matches (ES = 0.92). Likewise, the modified-side games showed a greater number of accelerations and decelerations than other types of matches (ES = 1.46-2.51). This work shows that friendly and training matches, in conjunction with modified-side games, are suitable tools to prepare soccer players for official matches.



#13 High metabolic load distance in professional soccer according to competitive level and playing positions

Reference: PeerJ. 2022 Sep 20;10:e13318. doi: 10.7717/peerj.13318. eCollection 2022.

Authors: Tomás García-Calvo, José Carlos Ponce-Bordón, Eduard Pons, Roberto López Del Campo, Ricardo Resta, Javier Raya-González

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Summary: High metabolic load distance provides global information about the soccer players' total high-intensity activities. Thus, this study aimed to examine the Spanish professional soccer players' high metabolic load distance profile, comparing competitive level and playing positions. A total of 18,131 individual match observations were collected from outfield players competing during the 2018/2019 and 2019/20 seasons in the First and Second Spanish Professional Soccer Leagues (LaLiga™). High Metabolic Load Distance (HMLD; distance covered with a power consumption above 25.5 W·kg-1 and accelerations or decelerations (e.g., accelerating from 2 to 4 m·s-2 for 1 s) were included), and HMLD per minute (HMLDmin) were analyzed by the ChryonHego® video-tracking system. Players were classified according to their playing position as follows: Central Backs (CB), Full Backs (FB), Center Midfields (CM), Wide Midfields (WM), and Forwards (FW). No differences between competitive levels were found in any variable when all players were analyzed conjointly except for HMLDmin overall and during the second half. However, when playing positions were considered, differences between competitive levels were observed in all positions, mainly in HMLD and HMLD during the first-half variables. In addition, several differences between playing positions were observed, with CB presenting the lowest values in all variables compared to their counterparts in both competitive levels, whereas CM in First Division and WM in Second Division showed the highest values in the HMLD variables. The findings are of interest to analyze the HMLD in professional soccer players, enabling the adaptation and individualization of training in this population according to the competitive level and specific playing position of each player.



#14 Evaluation of Water Intake in Spanish Adolescent Soccer Players during a Competition

Reference: J Hum Kinet. 2022 Sep 8;83:59-66. doi: 10.2478/hukin-2022-0051. eCollection 2022 Aug.

Authors: María Del Mar Fernández-Álvarez, Judit Cachero-Rodríguez, Claudia Leirós-Díaz, Sergio Carrasco-Santos, Rubén Martín-Payo

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Summary: An optimal state of hydration is essential to maintaining health. The objective of this cross-sectional study was to evaluate the water intake of adolescents aged 12 to 16 years and their hydration level during an official soccer match. Three hundred and six players participated in the study (N = 306). Their water intake was recorded and the level of hydration was evaluated using the density of urine as an indicator. Weight measurements were made before and after the match. Water intake control, urine collection and analysis, and the recording of minutes played were carried out after the match. The average weight loss was 746.2 g (SD: 474.07; p < 0.001), with 36.5% with less than 1% loss and 23.3% with more than 2% loss. The mean volume of water ingested was 229.35 ml (SD: 211.11) and a significant correlation was observed between minutes of activity (ρ-value = 0.206; p < 0.001), environmental humidity (ρ-value = - 0.281; p < 0.001), and temperature (ρ-value = 0.200; p < 0.001). The sweat rate was 0.69 l/h (SD: 0.56) and it was significantly associated with playing time (ρ-value = -0.276; p < 0.001). The mean urine density was 1.019 (SD: 0.007), with 64.9% of youth athletes showing dehydration (≥ 1.020). An association was observed between dehydration and activity time (U- value = 4.124; p < 0.001). Approximately 10% of the participants stated that they had not drunk any water during the match. In conclusion, it is necessary to establish individual hydration guidelines based on personal, environmental and activity-related factors, as well as establish a minimum volume of fluids to consume.



#15 Does the Self-Myofascial Release Affect the Activity of Selected Lower Limb Muscles of Soccer Players?

Reference: J Hum Kinet. 2022 Sep 8;83:49-57. doi: 10.2478/hukin-2022-0050. eCollection 2022 Aug.

Authors: Tomasz Michalski, Tomasz Król, Piotr Michalik, Magdalena Rutkowska, Magdalena Dąbrowska-Galas, Damian Ziaja, Michał Kuszewski

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Summary: Myofascial therapy has already become one of the basic forms of treatment of the locomotor system. One form of the therapy is Self-Myofascial Release, in which external force is applied to the body with the help of special rollers (foam rolling, FR). The aim of the study was to investigate the direct effect of Self-Myofascial Release of hamstring muscles using a foam roller on the bioelectric activity of selected muscles (biceps femoris and gluteus maximus) during squats. The study involved 40 male soccer players, who were randomly divided into two groups: experimental and control. The tests used did not show significant differences in the analyzed variables before the experiment (baseline measurement p > 0.05), while significant intergroup differences appeared for subsequent measurements, both for reference MVC values (p < 0.01 - for % gluteus maximus MVC, p < 0.001 - for % biceps femoris MVC) and for raw EMG values (p < 0.01 gluteus maximus and p < 0.001 - for % 0.0001 for biceps femoris). The use of self-myofascial release within the hamstring muscles leads to changes in the electrical potential of the muscles of the lower limb.



#16 External and Internal Training Loads for Intensive and Extensive Tactical-Conditioning in Soccer Small Sided Games

Reference: J Hum Kinet. 2022 Sep 8;83:165-173. doi: 10.2478/hukin-2022-0083. eCollection 2022 Aug.

Authors: Vinicius Zanetti, Marcelo Saldanha Aoki, Paul S Bradley, Alexandre Moreira

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Summary: This study aimed to investigate the external (ETLs; 15-Hz GPS unit coupled with a 100 Hz tri-axial accelerometer) and internal training loads (ITLs; session-RPE method) of 18 elite U20 soccer players (19 ± 1.0 years, 178 ± 8 cm, 71 ± 7 kg) undertaking a tactical-conditioning training program with special reference to small-sided games (SSGs). The SSGs used in this program were either extensive (SSG-extensive) or intensive (SSG-intensive) training sessions, that were alternated within the assessed weeks. Tactical principles of the game influenced the aim of the technical-tactical content. Total distance (TDR; ES: 1.17), and a very high-speed running distance (HSR; ES: 0.96) were greater in SSG-extensive vs. SSG-intensive. However, no meaningful difference was found for accelerations (ACC; ES: 0.12) and decelerations (DEC; ES: 0.08). However, a higher perceived intensity (session-RPE; ES: 0.62) and greater ITLs (ES: 0.27) were found for SSG-intensive. These findings suggest that coaches should prescribe SSG training sessions not only considering the usual variables (rules, player numbers, etc.). The current data indicate that the tactical objective of SSGs in relation to exercise bout duration and rest intervals should be considered, while implementing a multi-dimensional training monitoring program during SSG tactical-conditioning training sessions, integrating ETL and ITL variables to gain a better understanding of training responses.



#17 (Not) being granted the right to belong-Amateur football clubs in Germany

Reference: Int Rev Sociol Sport. 2022 Nov;57(7):1157-1174. doi: 10.1177/10126902211061303. Epub 2021 Dec 8.

Authors: Tina Nobis, Carlos Gomez-Gonzalez, Cornel Nesseler, Helmut Dietl

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Summary: Empirical studies show that first- and second-generation immigrants are less likely to be members of sports clubs than their non-immigrant peers. Common explanations are cultural differences and socioeconomic disadvantages. However, lower participation rates in amateur sport could be at least partly due to ethnic discrimination. Are minority ethnic groups granted the same right to belong as their non-immigrant peers? To answer this question, this paper uses publicly available data from a field experiment in which mock applications were sent out to over 1,600 football clubs in Germany. Having a foreign-sounding name significantly reduces the likelihood of being invited to participate. The paper concludes that amateur football clubs are not as permeable as they are often perceived to be. It claims that traditional explanations for lower participation rates of immigrants need to be revisited.



#18 Safety of International Professional Sports Competitions During the COVID-19 Pandemic: The Association Football Experience

Reference: Sports Med. 2022 Sep 27;1-4. doi: 10.1007/s40279-022-01763-3. Online ahead of print.

Authors: Horacio Caniza, Francisco Forriol, Osvaldo Pangrazio, Mario Gil-Conesa

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Summary: Major sporting events were suspended during the most acute phase of the COVID-19 pandemic. Competitions are resuming with enhanced hygiene protocols and altered mechanics. While risks for players and staff have been studied, the impact of large-scale tournaments on the communities that host them remains largely unstudied. CONMEBOL Copa América is one of the first wide-scale international tournaments to be conducted in its original format since the beginning of the COVID-19 pandemic. The tournament saw 10 national teams compete in four Brazilian cities during a period of heightened viral transmission. The analysis of over 28,000 compulsory PCR tests showed that positive cases did not lead to the uncontrolled spread of the disease among staff and players. More importantly, the data indicate that locally hired staff were not exposed to increased risk while working. The Copa América experience shows that international sporting competitions can be conducted safely even under unfavourable epidemiological situations.



#19 Repeated sprint ability in young football players according to the position and formation of the team: the effect of a specific training program

Reference: J Sports Med Phys Fitness. 2022 Sep 28. doi: 10.23736/S0022-4707.22.14129-0. Online ahead of print.

Authors: Vassilis Samolis, Nikolaos Koutlianos, Yiannis Michailidis, Athanasios Mandroukas, Kosmas Christoulas, Thomas Metaxas

Summary: The aim of this study was to investigate the effect of a specific training program for 12-weeks (twice a week) on the repeated sprint ability (RSA), according to the position of the football player in the formation of the team. Two groups of U-17 football players (experimental-group, n=22 and control-group, n=19) and five positions (central-defenders, wide-defenders, central-midfielders, wingers and central-attackers) according to the position in the formation (1-4-3-3) were studied. Sexual maturation was classified according to Tanner's stages. RSA and isokinetic strength were measured pre- and after the training program. The results showed that in RSA were differences in the factor time in the best (F=9.316, η2=0.383, p=0.008) and mean time (F=8.002, η2=0.348, p=0.013), but there were no differences between the groups. In strength, differences were observed in the time, mostly in the extensors at the three angular velocities (60°, 180°, 300°·sec-1) with differences in the group only in the maximum force (F=8.090, η2=0.366, p=0.013). No differences between players' positions were observed. In conclusion, a specific training program seems to affect players' performance on repeated sprint ability and the specific training in the players' position according to the team formation has a positive effect on the muscle power of football players.






Effects of small‑sided games and running‑based high‑intensity interval training on body composition and fitness in U19 female soccer players

The aim of this study was to compare the effects of small-sided games (SSGs) and running-based high-intensity interval training (HIIT) on the body composition and physical fitness of youth female soccer players.






Classified metabolic power‑based measures in professional football players: comparison between playing positions and match period

The aim of this study was (i) provide reference data of metabolic power-based measures during professional football matches; and to (ii) analyze the between-position and between-halves differences of power-based measures during professional football matches.






Latest research in football - week 36 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Genetic profiles to identify talents in elite endurance athletes and professional football players

Reference: PLoS One. 2022 Sep 16;17(9):e0274880. doi: 10.1371/journal.pone.0274880. eCollection 2022.

Authors: David Varillas-Delgado, Esther Morencos, Jorge Gutiérrez-Hellín, Millán Aguilar-Navarro, Alejandro Muñoz, Nuria Mendoza Láiz, Teresa Perucho, Antonio Maestro, Juan José Tellería-Orriols

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Summary: The genetic profile that is needed to identify talents has been studied extensively in recent years. The main objective of this investigation was to approach, for the first time, the study of genetic variants in several polygenic profiles and their role in elite endurance and professional football performance by comparing the allelic and genotypic frequencies to the non-athlete population. In this study, genotypic and allelic frequencies were determined in 452 subjects: 292 professional athletes (160 elite endurance athletes and 132 professional football players) and 160 non-athlete subjects. Genotyping of polymorphisms in liver metabolisers (CYP2D6, GSTM1, GSTP and GSTT), iron metabolism and energy efficiency (HFE, AMPD1 and PGC1a), cardiorespiratory fitness (ACE, NOS3, ADRA2A, ADRB2 and BDKRB2) and muscle injuries (ACE, ACTN3, AMPD1, CKM and MLCK) was performed by Polymerase Chain Reaction-Single Nucleotide Primer Extension (PCR-SNPE). The combination of the polymorphisms for the "optimal" polygenic profile was quantified using the genotype score (GS) and total genotype score (TGS). Statistical differences were found in the genetic distributions between professional athletes and the non-athlete population in liver metabolism, iron metabolism and energy efficiency, and muscle injuries (p<0.001). The binary logistic regression model showed a favourable OR (odds ratio) of being a professional athlete against a non-athlete in liver metabolism (OR: 1.96; 95% CI: 1.28-3.01; p = 0.002), iron metabolism and energy efficiency (OR: 2.21; 95% CI: 1.42-3.43; p < 0.001), and muscle injuries (OR: 2.70; 95% CI: 1.75-4.16; p < 0.001) in the polymorphisms studied. Genetic distribution in professional athletes as regards endurance (professional cyclists and elite runners) and professional football players shows genetic selection in these sports disciplines.



#2 The use of sand as an alternative surface for training, injury prevention and rehabilitation in English professional football and barriers to implementation: a cross-sectional survey of medical staff

Reference: Sci Med Footb. 2022 Sep 19;1-9. doi: 10.1080/24733938.2022.2125566. Online ahead of print.

Authors: Mark C Richardson, Bryan English, Paul Chesterton

Summary: The purpose of the present study was to investigate the use of sand as an alternative surface for training, injury prevention and rehabilitation interventions in English professional football. A Secondary aim was to explore the potential barriers to implementation. All 92 teams from the male English professional football pyramid during the 2021-22 season were eligible to take part. A cross-sectional survey of the medical personnel (one per club) was conducted between June 2021 and December 2021 based on the RE-AIM framework. A total of 58 respondents (63% of all clubs) completed the survey. Only 18 (31%) of the clubs surveyed used sand-based interventions across the last 3 seasons. Respondents felt sand-based interventions would be effective at improving physiological gains (median 4, interquartile range [IQR] 4-5) and as part of injury prevention and rehabilitation strategies (4, IQR 3-4) but were indifferent in relation to its potential to improve sporting performance (3, IQR 3-4). Barriers to implementation of sand-based interventions within wider football were a lack of facilities, lack of awareness of its potential benefits, lack of high-quality evidence and the surface not being specific to the sport. Medical staff also did not perceive that coaches' positively viewed sand interventions as a training or injury management strategy.



#3 Defining the attributes for specific playing positions in football match-play: A complex systems approach

Reference: J Sports Sci. 2020 Jun-Jun;38(11-12):1248-1258. doi: 10.1080/02640414.2020.1768636. Epub 2020 May 31.

Authors: Elise Berber, Scott McLean, Vanessa Beanland, Gemma J M Read, Paul M Salmon

Summary: Talent identification and development programmes that retain and develop athletes are integral to the sporting success of National Governing Bodies in football. Currently, player attributes are studied in isolation without considering the complexity of interacting components of football performance. The current study applied a systems analysis framework to describe, in a structured and systematic way, the attributes for specific playing positions in football match-play. Eight high-level football coaches were interviewed. Models of the interacting attributes were developed for each position using Work Domain Analysis (WDA). Six WDA models detail the attributes associated with each playing position. The models identified purposes of playing positions (restrict opposition actions, organise and coordinate, building up of offence, goal scoring and stretch opposition), performance-related measures and the functions required to achieve the playing position purposes (game play, psychological functions, time and space and player actions). Critically, the relationships between the purposes, measures, functions, processes, and objects are described in the models. The WDA models describe the interacting attributes of different playing positions in football match-play. The findings demonstrate football performance is complex, consisting of multiple interacting and dynamic components. Implications to support coaches in talent identification and development are discussed.



#4 Using global navigation satellite systems for modeling athletic performances in elite football players

Reference: Sci Rep. 2022 Sep 8;12(1):15229. doi: 10.1038/s41598-022-19484-y.

Authors: Frank Imbach, Waleed Ragheb, Valentin Leveau, Romain Chailan, Robin Candau, Stephane Perrey

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Summary: This study aims to predict individual Acceleration-Velocity profiles (A-V) from Global Navigation Satellite System (GNSS) measurements in real-world situations. Data were collected from professional players in the Superleague division during a 1.5 season period (2019-2021). A baseline modeling performance was provided by time-series forecasting methods and compared with two multivariate modeling approaches using ridge regularisation and long short term memory neural networks. The multivariate models considered commercial features and new features extracted from GNSS raw data as predictor variables. A control condition in which profiles were predicted from predictors of the same session outlined the predictability of A-V profiles. Multivariate models were fitted either per player or over the group of players. Predictor variables were pooled according to the mean or an exponential weighting function. As expected, the control condition provided lower error rates than other models on average (p = 0.001). Reference and multivariate models did not show significant differences in error rates (p = 0.124), regardless of the nature of predictors (commercial features or extracted from signal processing methods) or the pooling method used. In addition, models built over a larger population did not provide significantly more accurate predictions. In conclusion, GNSS features seemed to be of limited relevance for predicting individual A-V profiles. However, new signal processing features open up new perspectives in athletic performance or injury occurrence modeling, mainly if higher sampling rate tracking systems are considered.



#5 Relationships between Functional Movement Quality and Sprint and Jump Performance in Female Youth Soccer Athletes of Team China

Reference: Children (Basel). 2022 Aug 29;9(9):1312. doi: 10.3390/children9091312.

Authors: Junjie Zhang, Junlei Lin, Hongwen Wei, Haiyuan Liu

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Summary: This study aimed to determine the optimal functional movement screen (FMS) cut score for assessing the risk of sport injury, and to investigate the correlations between functional movement quality and sprint and jump performance. Twenty-four (N = 24) athletes performed all tests in one day at 10-30 min intervals, and the FMS test was performed first, without a warm-up session. After a standard warm-up, athletes then completed the Y-balance Test (YBT), sprint, counter-movement jump (CMJ), and standing long jump (SLJ), in turn. For each test, the best of three attempts was recorded for further analysis. A receiver operating characteristic (ROC) curve and area-under-the-curve (AUC) were used to determine the optimal FMS cut score for assessing the risk of sport injuries, and Spearman's rank correlation analysis was used to quantify associations between functional movement scores and athletic performance. The average FMS score was 16.2 and the optimal FMS cut score for assessing the risk of sport injuries was 14.5. There were moderate relationships between total FMS score and 10-20 m sprint time (r = -0.46, p &lt; 0.05), between In-line Lunge and 0-20 m sprint time (r = -0.47, p &lt; 0.05), between Shoulder Mobility and 0-10 m sprint time (r = -0.48, p &lt; 0.05), and between Trunk-stability Push-up and 10-20 m sprint time (r = -0.47, p &lt; 0.05). Moreover, Hurdle Step score was largely correlated with 0-10 m time (r = -0.51, p &lt; 0.05). For Y-balance, moderate correlations were observed between CMJ height and anterior asymmetry score (r = -0.47, p &lt; 0.05) and posteromedial asymmetry score (r = -0.44, p &lt; 0.05). However, there were no significant associations between YBT performance (asymmetric in three directions and composite score) and sprint performance (p &gt; 0.05). Taken together, the results indicate that a FMS score of 14 is not a gold standard for assessing the risk of injury in all populations; we recommend that the FMS cut score of 14.5 should be the optimal score for assessing risk of injury in young female elite soccer players. Moreover, the FMS and YBT were introduced to assess the quality of functional movements, and they cannot be used to assess sprint and jump performance. Practitioners can use components of the FMS that have similar characteristics to specific sports to assess athletic performance.



#6 Self-Report versus Neuropsychological Tests for Examining Executive Functions in Youth Soccer Athletes-A Cross-Sectional Study

Reference: Behav Sci (Basel). 2022 Sep 19;12(9):346. doi: 10.3390/bs12090346.

Authors: Florian Heilmann

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Summary: Cognitive diagnostics, especially the measurement of executive functions (EFs) in the context of sports and talent diagnostics, is a popular research topic. However, research is lacking on how self-reports are sufficient to examine the EFs of youth athletes for performance diagnostics. Thus, the current study aims to evaluate the relationships between neuropsychological tasks (3-back task, cued Go/NoGo task, flanker task, and number-letter task) and a self-report for examining EFs (BRIEF-SB). Furthermore, it should be investigated whether it is possible to predict the outcome of EF tasks using a self-report inventory. Therefore, 68 young professional soccer players (Mage = 14.26 ± 1.35 years) from a national youth academy were included in the study. The weak-to-moderate correlations (r = 0.000, p = 0.999 to r = -0.442, p &lt; 0.01) and the results of sensitivity analysis (0.125 to 0.538) do not support using a self-report of EFs for cognitive performance diagnostics. The inventory is only suitable for identifying executive dysfunctions in athletes recovering from head injuries or concussions.



#7 Design and Reliability of an Observational Framework to Evaluate the Individual Offensive Behavior in Youth Soccer-The INDISOC Tool

Reference: Children (Basel). 2022 Aug 29;9(9):1311. doi: 10.3390/children9091311.

Authors: Joaquín González-Rodenas, Iván Villa, Andrés Tudela-Desantes, Rodrigo Aranda-Malavés, Rafael Aranda

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Summary: Despite the great development of match analysis in professional soccer during the last decade, very few studies have assessed the individual technical and tactical behaviors of youth soccer players. The purpose of this paper was to design and assess the reliability of an observational instrument to evaluate the INDIvidual offensive behavior in competitive 7 and 11-a-side SOCcer (INDISOC). A total of eight experts in soccer training and analysis were included in the design of the tool by means of meetings and exploratory observations. This process involved design and re-design steps of the INDISOC tool to its final format which includes twelve dimensions related to the spatial, technical, and tactical constraints of individual behavior in soccer. The unit of analysis was the individual ball possession (IBP), described as the time that starts when a player can perform an action with the ball, and which ends when the IBP for another player begins. In the INDISOC tool, the IBP is analyzed taking into account three temporal moments: (1) receiving the ball, (2) processing the ball, and (3) culminating the individual action. Inter-observer and intra-observer analyses were performed and the kappa (K) coefficients were calculated to test the instrument reliability. The K values showed optimal inter (7-a-side: 0.73-0.95; 11-a-side: 0.76-0.98) and intra-observer (7-a-side: 0.84-1;11-a-side: 0.79-1) reliability levels. These results support the notion that the INDISOC observational tool could be a suitable instrument for analyzing the individual offensive behavior in competitive youth (7-a-side), junior and senior (11-a-side) soccer.



#8 Acute Obturator Externus Injury in Professional Soccer Players: A Case Series

Reference: Medicina (Kaunas). 2022 Aug 23;58(9):1145. doi: 10.3390/medicina58091145.

Authors: Hye Chang Rhim, Ashley E Gureck, Ki-Mo Jang

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Summary: When patients present with hip or groin pain, proximal quadriceps or adductor injuries are often initially suspected. In this case report, however, we present three cases of professional soccer players who were found to have obturator externus injury. A 30-year-old player and a 24-year-old player complained of pain in the left side after long distance shooting during an in-season training session and a match, respectively. Another 24-year-old player complained of pain in the right side after long distance passing during a preseason training session. On physical examination, active hip external rotation and passive hip internal rotation and extension elicited pain in all three players. All three players underwent magnetic resonance imaging (MRI) which found obturator externus grade II injuries for two players and grade I injury for one player. Rehabilitation protocols included relative rest, cryotherapy, and electrotherapy over a period of one week. All patients were able to return to play after 10 days. Correct identification of obturator externus injury afforded our players a favorable prognosis and a relatively quick return-to-sport compared with quadricep or adductor injury.



#9 Effects of Dietary Intervention and Education on Selected Biochemical Parameters and Nutritional Habits of Young Soccer Players

Reference: Nutrients. 2022 Sep 6;14(18):3681. doi: 10.3390/nu14183681.

Authors: Monika Grabia, Renata Markiewicz-Żukowska, Joanna Bielecka, Anna Puścion-Jakubik, Katarzyna Socha

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Summary: In adolescence, the body requires sufficient amounts of adequate nutrients. This is especially important in the case of young athletes, for whom a nutrition plan should be as significant as a proper training plan. The aim of the study was a 17-week follow-up of the effects of individual and group nutrition intervention on changes in eating habits and selected biochemical parameters. 46 young soccer players aged 12-17 from the Soccer Academy in Northeastern Poland completed the study. One group received only individual recommendations, while the other additionally received group nutrition education. As a result of the dietary education, teenagers from the latter group consumed less saccharose (44 g vs. 39.2 g) in favor of digestible carbohydrates (266 g vs. 273 g) and dietary fiber (19.7 g vs. 22.2 g), further emphasizing the health-promoting profile of diets. The amount of fluid consumed (33% vs. 48% above 2 L of water a day) and the habits of the peri-workout hydration routine were also improved. Many of the participants (41%) reported faster regeneration while 26% experienced an overall better well-being. The short-term intervention produced positive results, but nevertheless it is the implementation of long-term dietary improvement schemes involving parents and coaches that should be the direction of future approaches.



#10 Can the Supido Radar Be Used for Measuring Ball Speed during Soccer Kicking? A Reliability and Concurrent Validity Study of a New Low-Cost Device

Reference: Sensors (Basel). 2022 Sep 17;22(18):7046. doi: 10.3390/s22187046.

Authors: David M Díez-Fernández, David Rodríguez-Rosell, Federico Gazzo, Julián Giráldez, Rodrigo Villaseca-Vicuña, Jose A Gonzalez-Jurado

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Summary: The aim was to analyze the reliability and validity of a low-cost instrument, based on a radar system, to quantify the kicking ball speed in soccer. A group of 153 male soccer players (under-13, n = 53; under-15, n = 54; under-18, n = 46) participated in this study. Each player performed three kicks on the goal in a standardized condition while the ball speed was measured with three different devices: one Radar Stalker ATS II® (reference criterion) and two Supido Radar® (Supido-front of the goal and Supido-back of the goal). The standard error of measurement (SEM) expressed as a coefficient of variation (CV) and the intraclass correlation coefficient (ICC) were employed for assessing the reliability of each instrument. Stalker and Supido-back showed very high absolute (CV = 4.0-5.4%) and relative (ICC = 0.945-0.958) reliability, whereas Supido-front resulted in moderate to low reliability scores (CV = 7.4-15%, ICC = 0.134-0.693). In addition, Lin's concordance correlation coefficient (CCC) values revealed an 'almost perfect' agreement between Stalker and Supido-back for the average (r = 0.99) and maximal (r = 0.98) ball speed, regardless of the ball speed range analyzed. However, Supido-front resulted in a poor degree of concordance (CCC = 0.688) and a high magnitude of error (17.0-37.5 km·h-1) with the reference Stalker radar gun. The Supido Radar® placed behind the goal could be considered a reliable and valid device for measuring ball speed in soccer.



#11 The Immunological and Hormonal Responses to Competitive Match-Play in Elite Soccer Players

Reference: Int J Environ Res Public Health. 2022 Sep 18;19(18):11784. doi: 10.3390/ijerph191811784.

Authors: Ryland Morgans, Patrick Orme, Eduard Bezuglov, Rocco Di Michele, Alexandre Moreira

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Summary: This study aimed to examine the salivary immunoglobulin A (s-IgA) and salivary cortisol (s-Cort) responses to competitive matches in elite male soccer players. Data were collected for 19 players (mean ± SD, age: 26 ± 4 years; weight: 80.5 ± 8.1 kg; height: 1.83 ± 0.07 m; body-fat 10.8 ± 0.7%) from a Russian Premier League team throughout a 6-week period during the 2021-2022 season. Physical match loads were measured through an optical tracking system. s-IgA and s-Cort were assessed one day before each match (MD - 1), 60-min before kick-off, 30-min post-match, and 48-h post-match (MD + 2). At 60-min before kick-off, s-IgA values were lower than at MD - 1 (90% CI difference 15.7-71.3 μg/mL). Additionally, compared to 60-min before kick-off, s-IgA was higher at 30-min post-match (90% CI difference 1.8-57.8 μg/mL) and at MD + 2 (90% CI difference 5.4-60.5 μg/mL). At 30-min post-match, s-Cort was higher than at 60-min before kick-off (90% CI difference 4.84-7.86 ng/mL), while on MD + 2 s-Cort was higher than at 60-min before kick-off (90% CI difference 0.76-3.72 ng/mL). Mixed model regressions revealed that longer playing time and total distance covered, and higher number of high-intensity accelerations, involved smaller s-IgA differences between 30-min post-match and 60-min before kick-off, and between 60-min before kick-off and MD + 2. Additionally, greater high-intensity and sprint distances, and a higher number of high-intensity and maximal accelerations, involved smaller s-Cort differences between 60-min before kick-off and MD + 2. In conclusion, the present results demonstrate that using salivary monitoring combined with match load may be a useful tool to monitor individual mucosal immunity and hormonal responses to match-play and the subsequent recovery periods in elite soccer players.



#12 Does the Number of Substitutions Used during the Matches Affect the Recovery Status and the Physical and Technical Performance of Elite Women's Soccer?

Reference: Int J Environ Res Public Health. 2022 Sep 14;19(18):11541.  doi: 10.3390/ijerph191811541.

Authors: Ronaldo Kobal, Rodrigo Aquino, Leonardo Carvalho, Adriano Serra, Rafaela Sander, Natan Gomes, Vinicius Concon, Guilherme Passos Ramos, Renato Barroso

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Summary: The aim of this study was to compare the effect of a new rule for substitutions (four and five) with the rule before the COVID-19 pandemic (up to three) on recovery status, physical and technical performance, internal workload, and recovery process in elite women soccer players. Thirty-eight matches from 2019 to 2020 from the Brazilian Championships were analyzed. All data for the two conditions (≤3 and 4-5 substitutions) were compared using an independent t-test. The physical demands measured by a global positioning system (GPS) and the technical (obtained from Instat) and internal workload (rating of perceived exertion [RPE]) were assessed. The recovery process was measured by the total quality recovery (TQR) 24 h after each match. No differences were observed in any physical and technical parameters between 4-5 and ≤3 substitutions (p &gt; 0.05). Moreover, 4-5 substitutions demonstrated lower RPE (p &lt; 0.001) and workload-RPE (p &lt; 0.001), higher TQR (p = 0.008), and lower time played by the player (p &lt; 0.001), compared to ≤3. Thus, the new provisory rule for substitutions improved the balance between stress and recovery.



#13 Effects of Eight-Week Circuit Training with Core Exercises on Performance in Adult Male Soccer Players

Reference: Eur J Investig Health Psychol Educ. 2022 Sep 1;12(9):1244-1256. doi: 10.3390/ejihpe12090086.

Authors: Guido Belli, Sofia Marini, Mario Mauro, Pasqualino Maietta Latessa, Stefania Toselli

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Summary: Core exercises have been widely promoted in the last 25 years. However, the scientific debate about its efficacy for improving individual and team sports performance is still open. Thus, the present study aims to investigate the effects of circuit training with a core exercise program on physical performance in competitive amateur soccer players. The training was conducted during the off-season period, two times per week for 8 weeks. Pre- and post-evaluations were conducted using the following tests: Y-Balance Test (YB), standing long jump (SLJ), medicine ball chest press (MBC), curl-up (CU), and Illinois Agility Test (IAT). A total of 19 adults were divided into an experimental group (EG, n = 11, age 22 years, weight 71.2 ± 4.8 kg, height 174 ± 5.8 cm) and a control group (CG, n = 8, age 22 years, weight 73.2 ± 4.1 Kg, height 176 ± 6.3 cm). The EG showed significant improvements in lower and upper body strength, core endurance and balance, whereas the CG did not report significant changes in the pre- and post-test comparison. Despite study limitations, our positive results show that circuit training with core exercises appears to be a good strategy for performance improvement in adult soccer players.



#14 Analysis of the Association between Internal and External Training Load Indicators in Elite Soccer; Multiple Regression Study

Reference: Sports (Basel). 2022 Sep 6;10(9):135. doi: 10.3390/sports10090135.

Authors: Sime Versic, Toni Modric, Borko Katanic, Mario Jelicic, Damir Sekulic

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Summary: The aim of this study was to identify the external training load (ETL) variables that are most influential on the session rating of perceived exertion (sRPE) during elite soccer training. The participants (n = 29) were adult male soccer players from a single team that competed in Croatia's highest national soccer competition in the 2021/2022 season. Data were collected using the 10 Hz Global Positioning System from 66 training sessions, and a total of 1061 training observations were undertaken. The univariate and multivariate relationships among the predictors (ETL variables) and the criterion (sRPE) were assessed using forward stepwise multiple regressions and Pearson's correlations, respectively. ETL variables explained 63% of the variance in the sRPE (Multiple R = 0.79; p &lt; 0.01), and the model was successfully cross-validated. The significant partial regressors were total distance (β = 0.66), metres per minute (β = -0.47), high-intensity accelerations (β = 0.22) and decelerations (β = 0.18), and sprint distance (β = 0.14). All ETL variables were significantly correlated with the sRPE (all p &lt; 0.01), with the highest correlations found for total distance covered (r = 0.70) and high-intensity accelerations and decelerations (r = 0.62 and 0.65, respectively). Such results show that (i) the total distance and acceleration rates during the training sessions are the most important predictors of the sRPE, and (ii) a combination of different ETL variables predicts the sRPE better than any individual parameter alone. This study shows that both the volume and intensity of training are related to players' internal responses. The findings ultimately provide further evidence to support the use of sRPE as a global measure of training load in soccer players.



#15 Muscle injury characteristics and incidence rates in men's amateur soccer: A one season prospective study

Reference: Res Sports Med. 2022 Sep 19;1-14. doi: 10.1080/15438627.2022.2122827. Online ahead of print.

Authors: Afxentios Kekelekis, Filipe Manuel Clemente, Eleftherios Kellis

Summary: The objectives of the study were to examine the incident rate (IR), characteristics, and mechanisms of muscle injuries of 121 men amateur soccer players that voluntarily participated in this project. Sixty-five muscle injuries with an overall IR of 3.62/1000 h, 95% CI 2.7-4.5, were reported. The most frequently injured muscle groups were the hamstrings (IR 1.78/1000 h, 95% CI 1.1-2.3), followed by the adductors (IR 1.5/1000 h, 95% CI 0.93-2.06). Most muscle injuries were characterized as mild (IR 2.3/1000 h, 95% CI 1.53-2.92) or minimal (IR 1.28/1000 h, 95% CI 1.16-2.39. Higher incidence of injury sustained during matches (IR 14.09 injuries/1000 h, 95% CI 9.49-18.7), than in training (IR 1.88 injuries/1000 h, 95% CI 1.19-2.56). The most frequent injury mechanisms were high-speed running (84.4%) and change of direction (44.4%), for hamstring and adductors-related groin injuries, respectively. Players aged over 24 years had a 7-fold increased risk to sustain a hamstring injury but a lower risk to sustain an adductor-related groin injury. Injury prevention and rehabilitation management strategies may reduce muscle injury rates in amateur soccer.



#16 Postural balance asymmetry and subsequent noncontact lower extremity musculoskeletal injuries among Tunisian soccer players with groin pain: A prospective case control study

Reference: Gait Posture. 2022 Sep 9;98:134-140. doi: 10.1016/j.gaitpost.2022.09.004. Online ahead of print.

Authors: Fatma Chaari, Sébastien Boyas, Sonia Sahli, Thouraya Fendri, Mohammed A Harrabi, Haithem Rebai, Abderrahmane Rahmani

Summary: Recent studies reported postural balance disorders in patients and soccer players with groin pain (GP) compared to controls. Since postural balance asymmetry identified after an initial injury contributes for subsequent injuries, identification of this asymmetry in soccer players with GP may highlight the risk of sustaining subsequent noncontact lower extremity musculoskeletal injuries in these players. Therefore, the aims of this study were to (i) examine static and dynamic unipedal postural balance asymmetry in soccer players with GP compared to healthy ones, and (ii) quantify the risk of subsequent noncontact lower extremity injuries in these players. Do soccer players with GP exhibit higher static and dynamic unipedal postural balance asymmetry, and higher risk of sustaining subsequent injuries compared to controls? In this prospective case control study, 27 soccer players with non-time loss GP (GP group: GPG), and 27 healthy ones (control group: CG) were enrolled. Static and dynamic unipedal postural balance asymmetry were evaluated with a force platform using symmetry index (SI), and Y-balance test (Y-BT), respectively. Additionally, subsequent noncontact lower extremity musculoskeletal injuries were tracked for 10 months. The GPG revealed higher (p < 0.01) SI in eyes closed condition, higher (p < 0.001) side-to-side asymmetry in anterior, posteromedial and posterolateral reach distances and in composite Y-BT score compared to CG. They showed lower (p < 0.001) composite score for injured limb and higher (p < 0.001) side-to-side asymmetry in posteromedial reach distance compared to the cut-off values of 89.6 % and 4 cm, respectively. Moreover, GPG exhibited higher odds (OR= 7.48; 95 % CI = 2.15, 26.00; p < 0.01) of sustaining subsequent injuries compared to CG. The Y-BT should be instituted into existing pre-participation physical examinations to screen for soccer players with non-time loss GP at an elevated risk of sustaining subsequent injuries. This could help coaches and clinicians make valid return to play decisions.



#17 The British Athletics Muscle Injury Classification grading system as a predictor of return to play following hamstrings injury in professional football players

Reference: Phys Ther Sport. 2022 Sep 7;58:46-51. doi: 10.1016/j.ptsp.2022.08.002. Online ahead of print.

Authors: Craig Tears, Glen Rae, Geoff Hide, Raj Sinha, John Franklin, Peter Brand, Farah Hasan, Paul Chesterton

Summary: Investigate the British Athletics Muscle Injury Classification (BAMIC) grading system as a predictor of return to play (RTP) following primary hamstring strain injury (HSI) and its agreement with the Peetron's classification system in professional footballers. A retrospective cohort study of 39 hamstrings strains in a professional English football club were identified. Two musculoskeletal radiologists reviewed historical MRI's and classified them against the BAMIC and Peetron's grading system. Classification, oedema length and cross-sectional area were compared against RTP. Pearson's correlation coefficient demonstrated a weak but statistically significant correlation between BAMIC and RTP (r = 0.32; 95%CI 0.01 to 0.58; p = 0.05). Maximum length of intramuscular oedema demonstrated weak correlations with RTP (r = 0.3; 95%CI -0.02 to 0.56; p = 0.06). Percentage cross sectional demonstrated a weak correlation with RTP (r = 0.02; 95%CI -0.3 to 0.33; p = 0.91). Multiple regression demonstrated that 16% of the variance in RTP was explained by the model. Kappa for the agreement between BAMIC and Peetron's was 0.21 (95%CI 0 to 0.42). A significant association between the grade of HSI on the BAMIC system and RTP was found. Findings suggest BAMIC could provide valuable prognostic information on the RTP.



#18 Analysis of Injury Patterns in Men's Football between the English League and the Spanish League

Reference: Int J Environ Res Public Health. 2022 Sep 8;19(18):11296. doi: 10.3390/ijerph191811296.

Authors: Juan Carlos Argibay-González, Christopher Vázquez-Estévez, Alfonso Gutiérrez-Santiago, Adrián Paramés-González, Xoana Reguera-López-de-la-Osa, Iván Prieto-Lage

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Summary: Injuries in professional football lead to reduced team performance and large financial losses. The aim of this study was to analyse injuries in the two best team competitions in the world (LaLiga and Premier League), establishing similarities and differences, as well as determining injury causation patterns. A total of 277 on-field injuries requiring a substitution were analysed (142 in the Spanish league and 135 in the English league). The analysis was performed using traditional statistical tests (frequency analysis, chi-square test) with SPSS 25 and a T-Patterns sequence analysis with THEME 5.0. In the Spanish league, there were a similar number of injuries in the first part of the season as in the second part of the season, while in the English league, they are more frequent in the first part of the season. In the Spanish league, injuries are more frequent in the first half of the match, while in the English league, they are more frequent in the second half. The type of player most frequently injured was the defender. Most of the injuries occurred without the presence of an opponent. The accumulated minutes during the season affect injuries of the muscular type. The most common type of injury in both leagues was a strain, followed by a sprain and a contusion. Although common injury patterns can be established between the two leagues, there are notable differences. One of the factors is determined by the English league calendar (many matches at Christmas). In Spain, there were more muscular injuries that were not caused by the opponent, while in England there were more tackling injuries. Age is a risk factor in the Spanish league. In this league, there is a moderately significant relationship between the number of injuries and the points won.



#19 Association of the ACTN3 rs1815739 Polymorphism with Physical Performance and Injury Incidence in Professional Women Football Players

Reference: Genes (Basel). 2022 Sep 12;13(9):1635. doi: 10.3390/genes13091635.

Authors: Juan Del Coso, Gil Rodas, Miguel Ángel Buil, Javier Sánchez-Sánchez, Pedro López, Joaquín González-Ródenas, Pablo Gasulla-Anglés, Álvaro López-Samanes, Sergio Hernández-Sánchez, Ane Iztueta, Víctor Moreno-Pérez

Summary: The p.R577X polymorphism (rs1815739) in the ACTN3 gene causes individuals with the XX genotype to be deficient in functional α-actinin-3. Previous investigations have found that XX athletes are more prone to suffer non-contact muscle injuries, in comparison with RR and RX athletes who produce a functional α-actinin-3 in their fast-twitch fibers. This investigation aimed to determine the influence of the ACTN3 R577X polymorphism on physical performance and injury incidence of players competing in the women's Spanish first division of football (soccer). Using a cross-sectional experiment, football-specific performance and epidemiology of non-contact football-related injuries were recorded in a group of 191 professional football players. ACTN3 R577X genotype was obtained for each player using genomic DNA samples obtained through buccal swabs. A battery of physical tests, including a countermovement jump, a 20 m sprint test, the sit-and-reach test and ankle dorsiflexion, were performed during the preseason. Injury incidence and characteristics of non-contact injuries were obtained according to the International Olympic Committee (IOC) statement for one season. From the study sample, 28.3% of players had the RR genotype, 52.9% had the RX genotype, and 18.8% had the XX genotype. Differences among genotypes were identified with one-way analysis of variance (numerical variables) or chi-square tests (categorical variables). Jump height (p = 0.087), sprint time (p = 0.210), sit-and-reach distance (p = 0.361), and dorsiflexion in the right (p = 0.550) and left ankle (p = 0.992) were similar in RR, RX, and XX football players. A total of 356 non-contact injuries were recorded in 144 football players while the remaining 47 did not sustain any non-contact injuries during the season. Injury incidence was 10.4 ± 8.6, 8.2 ± 5.7, and 8.9 ± 5.3 injuries per/1000 h of football exposure, without differences among genotypes (p = 0.222). Injury rates during training (from 3.6 ± 3.7 to 4.8 ± 2.1 injuries per/1000 h of training exposure, p = 0.100) and match (from 47.8 ± 9.5 to 54.1 ± 6.3 injuries per/1000 h of match exposure, p = 0.209) were also similar in RR, RX, and XX football players. The ACTN3 genotype did not affect the mode of onset, the time needed to return to play, the type of injury, or the distribution of body locations of the injuries. In summary, women football players with different genotypes of the p.R577X ACTN3 polymorphism had similar values of football-specific performance and injury incidence. From a practical perspective, the ACTN3 genotyping may not be useful to predict performance or injury incidence in professional women football players.






Seasonal variations of the relationships between measures of training monotony and strain in professional soccer players

The purposes of this study were (a) to determine the variations in internal and external measures of training monotony (TM) and strain (TS) in professional soccer players according to periods of the season and playing positions, and (b) to analyze the relationships between internal and external measures of TM and TS.





Etiology and Recovery of Neuromuscular Function Following Academy Soccer Training

To profile the etiology and recovery time-course of neuromuscular function in response to a mixed-content, standard training week in professional academy soccer players. We concurrently examined physical performance, cognitive function, and perceptual measures of mood and wellness states to identify a range of simple tests applied practitioners could use in the field as surrogate measures of neuromuscular function.





Latest research in football - week 35 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Effects of an experimental short-time high-intensity warm-up on explosive muscle strength performance in soccer players: A pilot study

Reference: Front Physiol. 2022 Aug 25;13:984305. doi: 10.3389/fphys.2022.984305. eCollection 2022.

Authors: Antonino Patti, Valerio Giustino, Norikazu Hirose, Giuseppe Messina, Stefania Cataldi, Giuseppe Grigoli, Alida Marchese, Giuseppe Mulè, Patrik Drid, Antonio Palma, Antonino Bianco

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Summary: This study aimed to evaluate the effects of an experimental short-time warm-up consisting of a small number of intermittent high-intensity sprints on explosive muscle strength performance in soccer players and to identify recovery times after performing the sprints. Furthermore, we evaluated the reliability of a smartphone app in jumping performance.  Twenty male soccer players were given the following tests: 1) the counter-movement jump (CMJ) test with the Microgate system, 2) the counter-movement jump (CMJ) test with the MyJump smartphone app, and 3) the handgrip strength test. The experimental short-time high-intensity warm-up was carried out 1 week after test administration. The warm-up consisted of three maximum sprints over 60 m with 120 s of recovery between sprints. Then, the tests were administered again: the vertical jump height (VJH) performances (five trials) were measured 90 s after the last sprint; the handgrip strength performances (three trials) were measured 120 s after the last vertical jump test. The maximum VJH was found in the third trial of the CMJ test, 330 s after the last sprint (p < 0.01), the result closest to the baseline. The lowest VJH was found in the first trial of the CMJ test, 90 s after the last sprint (p < 0.05). Pearson's analysis between the CMJ test with the Microgate system and the CMJ test with MyJump showed a strong correlation (R = 0.96). Lin's concordance correlation coefficient showed a substantial concordance (ρc = 0.959) between measures. This experimental short-time warm-up of high-intensity intermittent sprints appears to be a simple, quick, and efficient activity to accelerate soccer players' optimal performance.



#2 Evaluation of 10-Week Neuromuscular Training Program on Body Composition of Elite Female Soccer Players

Reference: Biology (Basel). 2022 Jul 17;11(7):1062. doi: 10.3390/biology11071062.

Authors: Alberto Roso-Moliner, Elena Mainer-Pardos, José Luis Arjol-Serrano, Antonio Cartón-Llorente, Hadi Nobari, Demetrio Lozano

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Summary: This study was conducted to investigate the effects of a 10-week neuromuscular training program (NMT) on the sum of six skinfolds (Σ6S) and body composition variables in elite female soccer players. Forty-four Spanish elite female soccer players (age: 24.0 ± 4.2 years; height: 164.3 ± 5.5 cm; body mass: 60.4 ± 5.5 kg; body mass index (BMI): 22.4 ± 2.2 kg/m2) were randomly assigned to a control group (CG) or to an experimental group (EG). Participants in the EG completed a specific NMT program of 24 min, three times per week, which included exercises from six different categories (mobility, dynamic stability, anterior chain strength, lumbopelvic control, posterior chain strength, and change of direction). The CG followed their normal strength and conditioning program. Pre- and post-intervention assessments included anthropometric measurements (weight, height, limb circumferences, and bone breadths), and subsequently, body composition factors BMI, Σ6S, body mass, muscle mass, and lean body mass were calculated. Nutrition was standardized by a nutritionist and also load monitored. A two-way mixed analysis of variance (group × time) revealed that there was a significant (p ≤ 0.001) group × time interaction between body mass, fat mass, and Σ6S in favor of NMT. A significant interaction was also observed for body skeletal muscle mass and lean body mass favoring NMT. The application of an NMT program seems to be a useful strategy to improve body composition in elite female soccer players.



#3 Relative age effects and the youth-to-senior transition in Italian soccer: the underdog hypothesis versus knock-on effects of relative age

Reference: Sci Med Footb. 2022 Sep 20;1-7. doi: 10.1080/24733938.2022.2125170. Online ahead of print.

Authors: Gabriele Morganti, Adam L Kelly, Gennaro Apollaro, Laura Pantanella, Mario Esposito, Alberto Grossi, Bruno Ruscello

Summary: Relative Age Effects (RAEs) appear largely throughout youth soccer. However, little is known about how RAEs at youth levels can impact transition at senior levels. Accordingly, this study aimed to : (a) provide further test of RAEs by exploring the birth quarter (BQ) distribution of 2,030 Italian players born from 1975 to 2001 who have played in any of the Youth National Italian Soccer Teams ; and (b) investigate how RAEs influence future career outcomes, by exploring the BQ distribution of players who completed the transition from youth squads to the Senior National Team (n = 182) Chi-square statistics revealed significantly skewed BQ distributions for all Youth squads (P values <0.0001), and for the cohort of players who completed the transition (P = 0.003). In contrast, results from the Odds Ratios highlighted how BQ4s were more likely to transition from youth-to-senior compared to BQ1s . Results showed BQ1s remained overrepresented at senior level due to a residual bias effect. Whereas BQ4s who were able to overcome selection processes at youth levels recorded the highest likelihood of competing at senior levels. Involving players' career trajectories in RAEs studies is needed to understand how RAEs impacts career outcomes of early selected players.



#4 Where do you go when your periods go?: A case-study examining secondary amenorrhea in a professional internationally-capped female soccer player through the lens of the sport nutritionist

Reference: Sci Med Footb. 2022 Sep 15. doi: 10.1080/24733938.2022.2123555. Online ahead of print.

Authors: Lloyd J F Parker, Kirsty J Elliott-Sale, Marcus Hannon, James P Morton, Graeme L Close

Summary: This case study follows a professional internationally capped female soccer player's two-year journey from eumenorrhea, through injury, to amenorrhea, and the challenges faced by the player and nutritionist. The two years are split into three sections: (1) longitudinal profiling of the player, (2) nutrition to support her return from injury, and (3) investigation into the observed secondary amenorrhea. The cause of amenorrhea was investigated through the assessment of energy availability via doubly labelled water, remote food photography, blood biomarkers and resting metabolic rate. Despite having secondary amenorrhea and anovulatory cycles, the player did not have low energy availability. This study shows the importance for practitioner's, particularly nutritionists, to not assume that all menstrual irregularities are caused by low energy availability and could be caused by a combination of factors (e.g. clinical, physiological, and psychological), which requires a multi-disciplinary investigation and intervention team. This study also showed that education needs to be provided about menstrual health to elite female soccer players as the player (i) believed that not having a period was beneficial for performance and unsure of possible health implications; (ii) was convinced that a one-day bleed indicated a regular menstrual cycle; and (iii) was reluctant to waste the practitioners time discussing menstrual issues and was nervous of finding out if she had an actual health issue. It is therefore crucial that players feel comfortable in discussing their menstrual status with practitioners to support their performance and long-term health.



#5 The effects of injury, contextual match factors and training load upon psychological wellbeing in English Premier League soccer players via season-long tracking

Reference: Eur J Sport Sci. 2022 Sep 15;1-22. doi: 10.1080/17461391.2022.2125834. Online ahead of print.

Authors: Sophie Grimson, Gary Brickley, Nicholas J Smeeton, Will Abbott, Adam Brett

Summary: The study aimed to track psychological wellbeing (PWB) across two consecutive soccer seasons examining the effects of injury, illness, training load (TL) and contextual match factors (playing status, match selection and individual win-rate). Furthermore, examine PWB prior to injury or illness event. Thirty-two English Premier League (EPL) soccer players completed the 'Warwick-Edinburgh Mental Wellbeing Scale' every two weeks. No differences were found for group averaged PWB across the seasons (52.2 ± 0.3 vs. 51.8 ± 1.1) (p >0.05). Previous 7-day TL measured using GPS (session duration, total distance, explosive distance, low-intensity distance, high speed distance (HSD) and sprint distance (SD)) were not related to current PWB (p > 0.05). Yet, previous 14-day HSD (r (385) = -0.095) and 21-day SD (r (385) = 0.100) were related to current PWB (p < 0.05). Only 100% (vs. 0%) win-rate in the previous 14-days to the questionnaire revealed a higher current PWB score (52.7 ± 4.7 vs. 50.9 ± 5.6 (p < 0.05)). PWB did not differ prior to an injury or illness event, when players were injured or had low contextual match factors at time of questionnaire or previous match, and the previous 7-days (p > 0.05). In conclusion, PWB fluctuations across the season are associated with prior TL and multiple negative results. But prior PWB was not linked to injury or illness events. Implications for prioritising interventions to improve PWB during periods of chronic high intensity TLs and losing streaks, monitoring PWB, and use in injury and illness prediction are discussed.



#6 Team-Builder: Toward More Effective Lineup Selection in Soccer

Reference: IEEE Trans Vis Comput Graph. 2022 Sep 16;PP. doi: 10.1109/TVCG.2022.3207147.

Authors: Anqi Cao, Ji Lan, Xiao Xie, Hongyu Chen, Xiaolong Zhang, Hui Zhang, Yingcai Wu

Summary: Lineup selection is an essential and important task in soccer matches. To win a match, coaches must consider various factors and select appropriate players for a planned formation. Computation-based tools have been proposed to help coaches on this complex task, but they are usually based on over-simplified models on player performances, do not support interactive analysis, and overlook the inputs by coaches. In this paper, we propose a method for visual analytics of soccer lineup selection by tackling two challenges: characterizing essential factors involved in generating optimal lineup, and supporting coach-driven visual analytics of lineup selection. We develop a lineup selection model that integrates such important factors, such as spatial regions of player actions and defensive interactions with opponent players. A visualization system, Team-Builder, is developed to help coaches control the process of lineup generation, explanation, and comparison through multiple coordinated views. The usefulness and effectiveness of our system are demonstrated by two case studies on a real-world soccer event dataset.



#7 Season Match Loads of a Portuguese Under-23 Soccer Team: Differences between Different Starting Statuses throughout the Season and Specific Periods within the Season Using Global Positioning Systems

Reference: Sensors (Basel). 2022 Aug 24;22(17):6379. doi: 10.3390/s22176379.

Authors: João Barreira, Fábio Y Nakamura, Ricardo Ferreira, João Pereira, Rodrigo Aquino, Pedro Figueiredo

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Summary: This study aimed to quantify the external match loads (EMLs) of a Portuguese u-23 soccer team, competing at the highest national level for the age group, comparing players with different starting status throughout a competitive season and specific blocks. Thirty-five outfield soccer players were split into three groups for the entire season analysis and for each 3-month block, based on the percentage of games played as a starter. The three groups consisted of "starters" (≥55% of the games as a starter), "fringe" (30-54%), and "non-starters" (&lt;30%). EMLs were recorded using 10 Hz GPS technology throughout the whole season (26 matches). Differences (p &lt; 0.05) were found for total distance (TD), exposure time, and the number of accelerations and decelerations between starters and non-starters throughout the season (d = 0.73 to 1.08), and within each block (d = 0.59 to 1.68). Differences were also found between starters and fringe players for the number of accelerations in Block 2 (p = 0.03; d = 0.69), and TD (p = 0.006; d = 1) and exposure time (p = 0.006; d = 0.95) in Block 3. Differences in the EML were almost always accompanied by large differences in game time. Our results highlight the differences in the EML of starters and non-starters, emphasizing the need for compensatory training, especially with players that obtain significantly less playing time, to prepare the players for match demands (e.g., high-intensity efforts such as sprinting, accelerations, and decelerations).



#8 COVID-19 as a Potential Cause of Muscle Injuries in Professional Italian Serie A Soccer Players: A Retrospective Observational Study

Reference: Int J Environ Res Public Health. 2022 Sep 5;19(17):11117. doi: 10.3390/ijerph191711117.

Authors: Giuseppe Annino, Vincenzo Manzi, Anas Radi Alashram, Cristian Romagnoli, Mattia Coniglio, Niloofar Lamouchideli, Marco Alfonso Perrone, Dolores Limongi, Elvira Padua

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Summary: The COVID-19 pandemic has shocked the entire planet. The soccer world has also suffered major upheavals, and many professional soccer players have been infected with the virus. The aim of this study was to evaluate the incidence of injuries in Italian Serie A professional soccer players before and during the COVID-19 pandemic. Methods: We evaluated the incidence of muscle injuries between four competitive seasons of the Italian Serie A (2016-2017, 2017-2018, and 2018-2019 pre-COVID-19 vs. 2020/2021 post-COVID-19) in professional soccer players. Results: Significant differences were found in muscular injuries between the post-COVID-19 season and the previous seasons (p &lt; 0.001). The median split of the players' positivity duration was of 15 days. The players' long positivity (PLP) group showed a significant number of muscular injuries compared to the players' short positivity (PSP) group (p &lt; 0.0014, ES = 0.81, Large). The total teams' days of positivity were significantly related to the total team number of muscular injuries (r = 0.86; CI 95% 0.66 to 0.94; p &lt; 0.0001). In conclusion, this data showed that the competitive season post-COVID-19 lockdown has a higher incidence of muscle injuries in Italian Serie A soccer players compared to the pre-pandemic competitive season.



#9 Anthropometric and Physiological Profiles of Hungarian Youth Male Soccer Players of Varying Ages and Playing Positions: A Multidimensional Assessment with a Critical Approach

Reference: Int J Environ Res Public Health. 2022 Sep 3;19(17):11041. doi: 10.3390/ijerph191711041.

Authors: Imre Soós, Krzysztof Borysławski, Michał Boraczyński, Ferenc Ihasz, Robert Podstawski

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Summary: This study aimed to create preliminary anthropometric and physiological profiles of Hungarian male soccer players belonging to different age categories (14, 15, 16, and 17-18-years) and assigned to different playing positions (forward, defender, midfielder, goalkeeper). Anthropometric and physiological profiles were created for four age groups: 14- (n = 20), 15- (n = 16), 16- (n = 22) and 17-18-year-olds (n = 23) representing the Hungarian soccer academy. Additionally, the variables were analyzed across the four player positions mentioned above. The mean values of body mass, fat mass and BMI were within normal limits, although in some cases the anthropometric and body composition values were too high, particularly among the 17-18-year-olds. The mean values of HRrest were lowest among the 15-year-olds. The highest mean and maximal values of rVO2max and rVO2/AT [57.6 ± 8.12 (43.8-68.3) and 51.2 ± 7.24 (38.9-60.8) mL/kg/min, respectively] were noted in 14-year-olds. Goalkeepers performed significantly better than the remaining soccer players in terms of the most anthropometric and physiological characteristics, except for the Yo-Yo test (p &lt; 0.001). The values of anthropometric parameters increased with age. As expected, the oldest group achieved the best results in the performance tests. Goalkeepers outperformed the players representing other playing positions in the tests when assessing lower limb strength, sprint performance (5- and 10-m distance), and agility tests. From a practical point of view, the presented anthropometric and physiological profiles of players representing different age groups and playing positions can be useful for soccer coaches, strength and conditioning specialists, and athletic trainers of other soccer clubs in terms of the individualization and optimalization of soccer training.



#10 Effect of Small-Sided Games with and without the Offside Rule on Young Soccer Players: Reliability of Physiological Demands

Reference: Int J Environ Res Public Health. 2022 Aug 24;19(17):10544. doi: 10.3390/ijerph191710544.

Authors: Igor Junio Oliveira Custódio, Renan Dos Santos, Rafael de Oliveira Ildefonso, André Andrade, Rodrigo Diniz, Gustavo Peixoto, Sarah Bredt, Gibson Moreira Praça, Mauro Heleno Chagas

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Summary: This study aimed to compare the physiological demand between three vs. three small-sided games (SSGs) with (3vs.3WITH) and without (3vs.3WITHOUT) the offside rule, as well as the within- and between-session reliability of this demand. Twenty-four U-17 soccer athletes performed various three vs. three (plus goalkeepers) SSGs with and without the offside rule. The data collection was performed within an eight-week period. Athletes' heart rate was monitored during the SSG. The variables analyzed were the percentage mean heart rate (HRMEAN%) and the percentage peak heart rate (HRPEAK%). For the analysis of within-session reliability, the mean value of the first two and last two SSG bouts performed within one day were used. The between-session reliability was calculated using the mean value of the four SSG bouts of each SSG type performed on two different days. In both SSGs, the values for reliability were significant and were classified as moderate to excellent. There were no significant differences in the physiological demand among SSG types. We concluded that the offside rule does not influence the physiological demand in a three vs. three SSG and the HRMEAN% and HRPEAK% present moderate to excellent reliability in a three vs. three SSG with and without the offside rule.



#11 The Effects of a Visual Stimuli Training Program on Reaction Time, Cognitive Function, and Fitness in Young Soccer Players

Reference: Sensors (Basel). 2022 Sep 3;22(17):6680. doi: 10.3390/s22176680.

Authors: Georgia Theofilou, Ioannis Ladakis, Charikleia Mavroidi, Vasileios Kilintzis, Theodoros Mirachtsis, Ioanna Chouvarda, Evangelia Kouidi

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Summary: The purpose of the present study was to examine whether a visual stimuli program during soccer training can affect reaction time (RT), cognitive function, and physical fitness in adolescent soccer players. Thirty-eight male soccer players aged 10-15 were randomly assigned to either the intervention (Group A) or the control group (Group B). At baseline and at the end of the 6-month study FITLIGHT Trainer, the Cognitive Function Scanner Mobile Test Suite, a Virtual Reality (VR) game, and the ALPHA-Fitness and the Eurofit test batteries were used to measure participants' abilities. After the baseline assessment, Group A followed their regular soccer training combined with a visual stimuli program, while Group B continued their regular soccer training program alone for 6 months. At the end of the 6-month study, Group A showed statistically significant improvements in simple RT by 11.8% (p = 0.002), repeated sprints by 13.4% (p ≤ 0.001), and Pen-to-Point Cognitive Function by 71.62% (p &lt; 0.001) and 72.51% for dominant and non-dominant hands, respectively. However, a between-groups analysis showed that there was no statistically significant difference between the two groups in most of the measurements studied. In conclusion, a visual stimuli training program does not seem to add any value to the traditional soccer training program for adolescents. Nevertheless, this study helps to underline the potential of newly emerging technology as a tool for the assessment of RT.



#12 Perspectives of the barriers and enablers to nutritional adherence in professional male academy football players

Reference: Sci Med Footb. 2022 Sep 20;1-12. doi: 10.1080/24733938.2022.2123554. Online ahead of print.

Authors: Jennie L Carter, David J Lee, Mayur K Ranchordas, Matthew Cole

Summary: Nutritional intake is important for young football players; however, little is known about the factors that influence their nutritional adherence. The aim of this study was to investigate players', sports nutritionists',and coaches' perspectives of the barriers and enablers to adhering to nutritional recommendations within a professional football club. Individual interviews, based on the Capability, Opportunity, Motivation - Behaviour (COM-B) model and Theoretical Domains Framework (TDF), were conducted with 13 players (18 ± 1.3 years), 12 sports nutritionists, and 10 coaches from 2, 12, and 10 professional football clubs, respectively. Thematic analysis was used to interpret the data. Seven key themes were generated relating to the players' barriers and enablers to nutritional adherence: (1) Capability: (a) Nutritional Knowledge; (b) Cooking Skills; (2) Opportunity: (c) Training Venue Food Provision; (d) Nutritionist Accessibility and Approachability; (e) Living Status: (3) Motivation: (f) Performance Implications; and (g) Role Modelling. Inadequate food provision within the training and home environment, and limited time with the sports nutritionist were key barriers to nutritional adherence in youth football players. Football clubs should allocate more time for sports nutritionists to deliver nutrition support and sports nutritionists should aim to control the players environment to support optimal nutritional intake.



#13 Self-Assessment of Physical Fitness and Health versus Motivational Value of Physical Activity Goals in People Practicing Fitness, Football, Martial Arts and Wheelchair Rugby

Reference: Int J Environ Res Public Health. 2022 Sep 2;19(17):11004. doi: 10.3390/ijerph191711004.

Authors: Katarzyna Kotarska, Celina Timoszyk-Tomczak, Leonard Nowak, Katarzyna Sygit, Izabela Gąska, Maria Alicja Nowak 

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Summary: The aim of the study was to determine the relationship between self-assessment of physical fitness and health, and the motivational role of physical activity goals in people, depending on their sports discipline. The study included 470 men and 218 women, aged 18-45, from western and southern Poland. The respondents practiced sports recreationally (fitness-F), competitively (football-FB, martial arts-MA), and for rehabilitation and sports purposes (wheelchair rugby-R). The standardized questionnaire for the motivational role of physical activity goals (Inventory of Physical Activity Objectives, IPAO) by Lipowski and Zaleski and the authors' questionnaire on lifestyle were used. In the statistical analyses, non-parametric statistics were used. Individuals with very high and high self-assessment of their physical fitness and very good self-assessment of health achieved higher scores on the motivational value scale, time management, motivational conflict and multidimensionality of physical activity goals (p &lt; 0.05). Respondents who assessed their health as very good achieved lower results on the perseverance scale, compared to those who assessed their health as good or poor. Self-assessment of physical fitness had a positive, high and moderate correlation with the self-assessment of health in people practicing wheelchair rugby, fitness, football and martial arts (r = 0.61; r = 0.52; r = 0.41; r = 0.40, respectively). Correlations were found between the motivational role and time management in people practicing fitness (r = 0.81), football (r = 0.66) and martial arts (r = 0.45), and multidimensionality of goals in those practicing fitness (r = 0.65) and martial arts (r = 0.42) Wheelchair rugby players scored the highest on all KCAF scales (except for motivational conflict). Self-assessment of physical fitness of wheelchair rugby players and fitness practitioners was negatively correlated with time management (r = -0.68; r = -0.49), multidimensionality of goals (r = -0.51; r = -0.49) and motivational values (r = -0.43; r = -0.43). The demonstrated relationships indicated that there was a need to strengthen the self-esteem and motivation for physical activity, promoting perseverance, the ability to focus on the implementation of one's goals and prioritizing the goals among people practicing various sports disciplines.



#14 Association between Fitness Level and Physical Match Demands of Professional Female Football Referees

Reference: Int J Environ Res Public Health. 2022 Aug 28;19(17):10720. doi: 10.3390/ijerph191710720.

Authors: María Luisa Martín Sánchez, José M Oliva-Lozano, Jorge García-Unanue, Peter Krustrup, Jose Luis Felipe, Víctor Moreno-Pérez, Leonor Gallardo, Javier Sánchez-Sánchez

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Summary: The aim of this study was to examine the physical demands for elite female referees during competitive matches and to evaluate the relationship between match performance and fitness levels. Seventeen female elite field referees were fitness-tested (29.0 ± 5.2 (SD) years, 163.8 ± 6.7 cm, 54.0 ± 5.1 kg, Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) performance 1610 ± 319 m) and were analysed during a total of 187 football matches. Global positioning systems (GPS) were used in this research. The physical demands were significantly lower (p &lt; 0.05) in the second half of matches compared to the first half. Regarding the acceleration-related variables, the female referees revealed a higher number of high-intensity actions in the first half compared to the second half. However, higher low-intensity demands were observed for the females referees in the second half compared to the first half in the total number of accelerations (ACC) (~70.48 n; ES = 0.61; p &lt; 0.05) and decelerations (DEC) (~71.11 n; ES = 0.62; p &lt; 0.05); total number of ACC in zone 1 (~85.27 n; ES = 0.70; p &lt; 0.05) and DEC in zone 1 (Z1) (~83.98 n; ES = 0.71; p &lt; 0.05); and distance covered accelerating and decelerating in Z1. The distance covered in YYIR1 and the performance in the repeated sprint ability test correlated with the physical demands during matches for female football referees (p &lt; 0.05). In conclusion, this study described the physical performance profile of female football referees and differences between the first and second halves of matches were observed. The results of this study revealed positive correlations between intermittent exercise fitness levels, the repeated sprint ability performance and match performance in female football referees, and thus this information can be implemented in their training plan designs.



#15 Adaptation to stress in football athletes: The importance of cognitive appraisal

Reference: Front Psychol. 2022 Aug 24;13:939840. doi: 10.3389/fpsyg.2022.939840. eCollection 2022.

Authors: A Rui Gomes, Clara Simães, Catarina Morais, Ricardo Cunha

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Summary: This study analysed the adaptation of football athletes to competitive stressors regarding the upcoming match. For that, the study adopted a cross-sectional methodology using a critical incident approach. The participants were 352 young male football athletes, aged between 15 and 19 years (M = 16.91, SD = 0.99), who were competing in the national football championship. The results indicated that cognitive appraisal partially mediated the relationship between competitive stressors and emotions: athletes who perceived stressors as a challenge, tended to feel more control over the situation and more resourceful (coping perception), leading to a more positive emotional experience, while those perceiving the stressors as a threat were more prone to experience less control and more negative emotions. This mediation model was moderated by athletes' competitive level (U17 or U19), as the role of challenge perception was more pronounced in the U19 team, while the relationship between threat perception and less control was only observed for the U17 team. In sum, the data reveals the importance of cognitive appraisal in young football athletes' adaptation to competitive stressors, bolstering the theoretical models in this area and the importance of psychologists to consider these variables during intervention, particularly cognitive appraisal.



#16 The impact and experienced barriers menstruation present to football participation in amateur female footballers

Reference: J Sports Sci. 2022 Sep 13;1-14. doi: 10.1080/02640414.2022.2122328. Online ahead of print.

Authors: Cecile J J Pinel, Ritan Mehta, Katrine Okholm Kryger

Summary: This study (1) assessed the impact different stages of the menstrual cycle has on experienced football performance and exercise ability (2) identified the experienced barriers to football participation menstruation presents in amateur women footballers. An online survey was used. The inclusion criteria were non-professional, women currently experiencing regular menstrual cycles, ≥18 years, ≥60 min football/week in the UK. Descriptive statistics were performed on quantitative data and thematic analysis of the open-ended questions. 127 responses were included. Most of the respondents were aged between 18-25 (89%), Caucasian (83%) and competing in Universities Leagues (69%). Menstruation was reported to "never" limit football playing in 17%, "sometimes" in 47%, "rarely" in 25% and "always" in 10% of respondents. The majority (73%) reported one or more barriers menstruation present to football participation. Following thematic analysis, 165 meaning units, 23 themes and seven categories were identified. Confidence and aerobic capacity/endurance were identified to be the aspects most negatively impacted during the pre-menstrual and menstrual stages. Confidence is likely to be negatively impacted due to the barriers identified. Thus, recommendations on how to reduce these through education of players and involved staff, at the club and the FA level have been made.



#17 Investigating the delivery of health improvement interventions through professional football club community trusts-strengths and challenges

Reference: Public Health Pract (Oxf). 2021 Mar 19;2:100104. doi: 10.1016/j.puhip.2021.100104. eCollection 2021 Nov.

Authors: A R Pringle, S Zwolinsky, L Lozano-Sufrategui

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Summary: This study audits health improvement provision delivered in/by English professional Football Club Community Trusts and reports the strengths and challenges around the implementation of interventions. Data were collected through (i) a review of trust websites (n = 72), (ii) an online survey (n = 34/47.2%) and (iii) semi-structured interviews (n = 11/32.3%) with a sub-sample of trust managers. The review of websites confirms all trusts provided physical activity-led interventions. The online survey showed most managers were male (n = 23/67.7%) and white British (n = 30/88.2%). Two thirds held management roles, (n = 23/67.6%) and represented Championship (n = 12/35.2%), League 1 (n = 13/38.2%) and League 2 clubs (n = 9/26.5%). Trusts provided physical activity and most provided diet (n = 31/91.2%) as well as smoking (n = 20/58.8%) and alcohol (n = 19/55.9%) interventions. Weight management, (n = 25/73.5%), mental health interventions (n = 28/82.4%) were offered. Trusts provided male-specific (n = 20/58.8%), with fewer providing female-specific interventions (n = 15/44.1%). Most trusts (n = 30/88.2%) evaluated interventions. 80.8% (n = 21/26) used public health guidance for programme design, 69.2% (n = 18/26) delivery, 57.7% (n = 15/26) needs assessment and 50% (n = 13/26) evaluation. Interviews and qualitative reports identified strengths including, using football, the 'club brand', 'meeting health needs' and 'working as a strategic collaboration with partners'. Challenges included 'short-term funding staffing, mainstreaming, and evaluating interventions'. Football Community Trusts deliver interventions, but challenges were encountered when implementing these programmes.



#18 Motivational predictors of children's involvement in out-of-school activities: An application of a football program

Reference: Scand J Med Sci Sports. 2022 Sep 15. doi: 10.1111/sms.14236. Online ahead of print.

Authors: Esben Elholm Madsen, Peter Krustrup, Tina Hansen, Charlotte Sandager Aggestrup, Nikos Ntoumanis, Carsten Hvid Larsen, Kristina Pfeffer, Andreas Ivarsson, Knud Ryom, Malte Nejst Larsen, Mads Madsen, Jeppe Elholm Madsen, Anne-Marie Elbe

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Summary: The "11 for Health in Denmark" in-school educational football program has shown to have numerous positive physiological and psychological effects in 10- to 12-year-old schoolchildren. A key part of the successful application of the program, however, has not yet been examined, namely the motivational processes underlying participation and behavioral changes. This study examined such motivational processes (i.e., autonomous motivation, beliefs, and intentions) using the trans-contextual model (TCM) and investigated if the 11 for Health in Denmark program increased intentions to participate in physical activity (PA) outside of school in 10- to 12-year-old schoolchildren. Using a web-based questionnaire, Danish-speaking schoolchildren (N = 276 [boys, 50.4%]; Mage = 10.44, SD = 0.35) from three schools and seven classes completed TCM-based questionnaires at three time-points (weeks 0, 1, and 5) while participating in the 11 for Health in Denmark program. Single-indicator structural equation modeling was performed to examine goodness-of-fit and parameter estimates. A path analysis using maximum likelihood estimation was used to test the direct and indirect effects of the TCM model. The results partly supported a mediation sequence, as we found significant direct effects in eight of 13 motivational variables (β = -0.25-0.83, p < 0.05), indirect effects in one of nine variables (β = 0.15, p < 0.01), but no effects with regard to PA behavior. Findings provide evidence for a motivational link between Danish-speaking schoolchildren's autonomous and controlled motivation from in school to out of school, and may inform future interventions promoting motivation and participation in out of school PA.






The ability of energy recovery in professional soccer players is increased by individualized low-intensity exercise

The aim of this study was to investigate whether individualized low-intensity exercise (ILIE) within the recovery domain before lactate threshold 1 (LT1) improves energetic recovery and general endurance capacity in professional soccer players.





The Effects of Physiological Demands on Visual Search Behaviours During 2 vs. 1 + GK Game Situations in Football

We examined the effect of physiological workload on gaze behaviour during defensive performance in 2 vs. 1 + goalkeeper game situations in football.





Latest research in football - week 34 - 2022

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Cold Water Immersion Improves the Recovery of Both Central and Peripheral Fatigue Following Simulated Soccer Match-Play

Reference: Front Physiol. 2022 Aug 15;13:860709. doi: 10.3389/fphys.2022.860709. eCollection 2022.

Authors: Mustapha Bouchiba, Nicola Luigi Bragazzi, Slim Zarzissi, Mouna Turki, Firas Zghal, Mohamed Amine Grati, Wael Daab, Fatma Ayadi, Haithem Rebai, Hassen Ibn Hadj Amor, Thomas J Hureau, Mohamed Amine Bouzid

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Summary: The present study aimed to investigate the effect of cold water immersion (CWI) on the recovery of neuromuscular fatigue following simulated soccer match-play. In a randomized design, twelve soccer players completed a 90-min simulated soccer match followed by either CWI or thermoneutral water immersion (TWI, sham condition). Before and after match (immediately after CWI/TWI through 72 h recovery), neuromuscular and performance assessments were performed. Maximal voluntary contraction (MVC) and twitch responses, delivered through electrical femoral nerve stimulation, were used to assess peripheral fatigue (quadriceps resting twitch force, Qtw,pot) and central fatigue (voluntary activation, VA). Performance was assessed via squat jump (SJ), countermovement jump (CMJ), and 20 m sprint tests. Biomarkers of muscle damages (creatine kinase, CK; Lactate dehydrogenase, LDH) were also collected. Smaller reductions in CWI than TWI were found in MVC (-9.9 ± 3%vs-23.7 ± 14.7%), VA (-3.7 ± 4.9%vs-15.4 ± 5.6%) and Qtw,pot (-15.7 ± 5.9% vs. -24.8 ± 9.5%) following post-match intervention (p < 0.05). On the other hand, smaller reductions in CWI than TWI were found only in Qtw,pot (-0.2 ± 7.7% vs. -8.8 ± 9.6%) at 72 h post-match. Afterwards, these parameters remained lower compared to baseline up to 48-72 h in TWI while they all recovered within 24 h in CWI. The 20 m sprint performance was less impaired in CWI than TWI (+11.1 ± 3.2% vs. +18 ± 3.6%, p < 0.05) while SJ and CMJ were not affected by the recovery strategy. Plasma LDH, yet no CK, were less increased during recovery in CWI compared to TWI. This study showed that CWI reduced both central and peripheral components of fatigue, which in turn led to earlier full recovery of the neuromuscular function and performance indices. Therefore, CWI might be an interesting recovery strategy for soccer players.



#2 Analysis of the most demanding passages of play in elite youth soccer: a comparison between congested and non-congested fixture schedules

Reference: Sci Med Footb. 2022 Aug 29;1-8. doi: 10.1080/24733938.2022.2117404. Online ahead of print.

Authors: Sergio L Jiménez, Nuno Mateus, Anthony Weldon, Álvaro Bustamante-Sánchez, Adam L Kelly, Jaime Sampaio

Summary: This study aimed to examine the most demanding passages of play in elite youth soccer for congested and non-congested fixture schedules. Seventeen elite youth male soccer players (18.2 ± 1.3 years old) participated in this study across 30 competitive matches. Assessed matches included congested (n = 12, three matches within eight consecutive days or less) and non-congested matches (n = 18, at least 5 days between matches). The players' activity profiles during matches were analysed using global positioning measurement units (GPS). Players activity included: distance covered, distance covered at different velocities, high-intensity accelerations and decelerations, and player load. The most demanding passages (MDP) of match play was calculated using a moving average method within three-time windows (i.e., 1, 5, and 10 min). Data were analysed using a Bayesian ANOVA. During congested fixtures, the players' distance covered and player load declined, with the former decreasing across all the MDP time windows, whereas the latter exclusively into the long-time windows (i.e., 5 and 10 min). Conversely, statistical differences in the remaining variables were anecdotal and in favour of the null hypothesis (i.e., Bayes factor <1), suggesting a non-influence of the competition fixture schedule. These findings provide insight into the MDP of youth soccer, helping practitioners to periodize training and recovery strategies during different competitive fixture schedules.



#3 Resumption of professional football league with spectators during the COVID-19 pandemic: The implementation of Bio-secure bubble protocol

Reference: Qatar Med J. 2022 Jul 26;2022(3):31. doi: 10.5339/qmj.2022.31. eCollection 2022.

Authors: Abdul Wahab Al Musleh, Naushad Ahmad Khan, Sameer Abdurahiman, Mohammad Asim, Ayman El-Menyar, Gordon Penney, Hassan Al-Thani

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Summary: Elite professional sports events involving mass gatherings carry a high risk of viral transmission during the coronavirus disease of 2019 (COVID-19) pandemic. We describe the potential impact of resuming professional football leagues involving international participants adhering to a strict Bio-secure bubble protocol and investigate the consequences of spectators/fan attendance at such mass events during the ongoing COVID-19 pandemic in Qatar. We conducted a descriptive cohort study involving football players, referees, match officials, local organizing committee (LOC) members, hotel and security staff working in close coordination, and over 10,000 spectators from the Asian Football Confederation (AFC) Champions League (East) and the final match. The study covered almost four weeks of the event (November 19 to December 19, 2020) under a robust Bio-secure bubble protocol. It included extensive severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) RT-PCR (reverse transcription-polymerase chain reaction) every 3-6 days and clinical symptom monitoring on and off the field. Target variables included positive RT-PCR results and clinical symptom monitoring among participants, and rapid antigen testing for fan attendance to examine their safe return to the stadiums. A total of 12,250 RT-PCR tests involving 3158 individuals in the Bio-secure bubble were done over one month for all the AFC (East) matches, including the final match. Overall, 44 matches involving 16 teams were played. During the championship, only five individuals (three LOC members and two match officials) returned positive for COVID-19 infections. Four individuals (three team staff/officials and one person outside the Bio-secure bubble) had reactive results. None of the players tested positive for COVID-19 infection. All individuals testing positive were asymptomatic or had mild symptoms, with no one requiring hospitalization other than symptomatic treatment. The overall positivity rate was 0.15% for the entire duration of the AFC (East) Champions League. For the final match, a total of 10,320 rapid antigen tests were done for spectators, of which only one test was positive for COVID-19. This report shows a very low incidence rate of COVID-19 infections during mass gathering events at the international level. For the resumption of football with spectators, careful mitigation strategies should be considered to reduce the risk of transmission to a sufficiently safe level. This may require proper coordination and measures (i.e., physical distancing, testing, entry, and exit routes in the stadium, and seating arrangement inside the stadium with limited attendance). Based on this, during the ongoing COVID-19 pandemic, the supervised and controlled resumption of football matches with spectators can be done safely provided that a strict Bio-secure bubble protocol has been implemented.



#4 Influence Mechanism of the Home Advantage on Referees' Decision-Making in Modern Football Field - A Study From Sports Neuro-Decision Science

Reference: Front Psychol. 2022 Aug 11;13:873184. doi: 10.3389/fpsyg.2022.873184. eCollection 2022.

Authors: Li Zhang, Hongfei Zhang, Shaopeng Li, Jianlan Ding, Yuxiao Peng, Zeyuan Huang

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Summary: As professional football stadiums continue to grow in popularity worldwide, fans are able to watch the game in closer proximity, but the design of professional football stadiums to shorten the distance between fans and the playing field also exacerbates the impact of the home advantage on the referee's decision to call a penalty. Studies have confirmed the existence of the home advantage and found that experienced referees can reduce the impact of this interference, but the neural mechanisms behind this phenomenon have not been adequately investigated. In this study, we designed a soccer referee decision making task based on a home field effect scenario in a real soccer game, and used event-related potentials (ERPs) to compare the decision making and EEG differences between individuals with different experience levels when faced with foul actions under spectator noise interference. The experiments showed that individuals with different experience levels triggered a significant ERN EEG component when performing the penalty decision task under the home field effect factor, suggesting that the interference of the home field effect may lead referees to correct their previous decision-making behavior patterns in the penalty decision and reduce unfavorable calls against the home team. In contrast, referees with officiating experience elicited smaller ERN amplitudes compared to other subjects, suggesting that experience factors may inhibit this tendency to change behavioral patterns. This study suggests that in response to the increasing trend of professional football stadiums, policy makers should place more emphasis on enhancing the experience level of referees in the training of referees to ensure the fairness of the game.



#5 Application of Image Processing Technology in the Diagnosis of Football Injury

Reference: Appl Bionics Biomech. 2022 Aug 5;2022:5926098. doi: 10.1155/2022/5926098. eCollection 2022.

Authors: Liyun Xu, Zhubo Xu

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Summary: With the hot development of football, sports injuries caused by football have also received special attention. In football games, although there are medical staff on and off the field always on call to protect the safety of players, because of the complexity of diagnosis work, medical staff can easily lead to diagnostic errors due to factors such as fatigue, which seriously affects the condition of athletes. Image processing is a technology that uses computer to process images, which can greatly overcome the uncertain factors brought by manual diagnosis. Based on this, this paper uses image processing technology and pattern recognition as technical means to explore the specific application of image processing in football injury diagnosis. This paper firstly takes football clubs as the main research object and analyzes and explores the specific utility of image segmentation and feature recognition in sports injury image processing. Then, starting from the relevant image features, the paper analyzes and compares the sensitivity of support vector machine pattern recognition and neural network pattern recognition in football injury diagnosis. This article comprehensively summarizes the application of image processing technology in the diagnosis of football injuries and puts forward constructive suggestions for its subsequent development. Experiments show that the effect of pattern recognition is often different for different injury parts of football. Among them, the sensitivity of pattern recognition based on image processing can reach 68.9%, and the detection rate of football injuries can also be maintained at about 81.2%. This fully shows that image processing technology can play an active role in the actual football injury diagnosis, and provide very valuable information for clinical diagnosis.



#6 Rate of torque development as a discriminator of playing level in collegiate female soccer players

Reference: J Musculoskelet Neuronal Interact. 2022 Sep 1;22(3):326-335.

Authors: Ty B Palmer, Kazuma Akehi

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Summary: This study aimed to examine the efficacy of isometric knee extension and flexion peak torque and rate of torque development (RTD) variables to distinguish starters from non-starters in collegiate female soccer players. Eleven starters (20±2 years) and 13 non-starters (19±1 years) performed three isometric maximal voluntary contractions of the knee extensors and flexors. Peak torque, peak RTD, and RTD at 0-100 (RTD100) and 0-200 (RTD200) ms were obtained from each contraction. The starters produced significantly greater (P=0.002-0.015) knee extension and flexion peak RTD, RTD100, and RTD200 values than the non-starters. There were no significant differences (P>0.050) between the starters and non-starters for peak torque. Discriminant analysis revealed thresholds of 9.36, 7.98, and 6.97 Nm⋅s-1⋅kg-1 for knee extension RTD200 and knee flexion peak RTD and RTD100, respectively. These thresholds showed 81.8% sensitivity and 76.9 to 92.3% specificity for identifying playing group membership. Our findings indicate that RTD may be a better parameter than peak torque at differentiating between playing level in collegiate female soccer players. The discriminant analysis thresholds for the RTD variables demonstrated good sensitivity and specificity, and therefore, may be used as indices to identify players with a high degree of soccer playing ability.



#7 MAN v FAT Soccer: Feasibility Study and Preliminary Efficacy of a Sport-Based Weight-Loss Intervention for Overweight and Obese Men in Australia

Reference: J Sport Exerc Psychol. 2022 Aug 30;1-11. doi: 10.1123/jsep.2021-0165. Online ahead of print.

Authors: Timothy Budden, James A Dimmock, Michael Rosenberg, Mark R Beauchamp, Ian Fitzpatrick, Ben Jackson

Summary: MAN v FAT Soccer is a sport-based weight-loss program for overweight and obese men that originated in the United Kingdom (i.e., as MAN v FAT Football) and appears to successfully engage men with weight loss. We sought to explore whether the program would work in an Australian context by (a) establishing a foundation for the implementation of the program on a larger scale and (b) determining how large-scale implementation is most feasible. We conducted a nonrandomized, single intervention group feasibility trial of MAN v FAT Soccer in Australia with 418 male participants with a body mass index greater than 27.50 kg/m2. Results indicate that the program is acceptable, with participants reporting positive perceptions of the various components of the program and a high proportion reporting intentions to recommend the program to others (95.9%). Furthermore, preliminary effectiveness results indicate positive changes in weight (4.6% reduction) and physical activity (88.5% increase) and improvements in psychological outcomes such as depression (17.6% decrease), stress (19.0% decrease), and body appreciation (19.1% increase). Our findings provide general support for the feasibility of MAN v FAT Soccer and the notion that leveraging competition and masculinity may help drive men's health behavior change.



#8 Bilateral Training Improves Agility and Accuracy for Both Preferred and Non-Preferred Legs in Young Soccer Players

Reference: Percept Mot Skills. 2022 Sep 2;315125221124373. doi: 10.1177/00315125221124373.

Authors: Ahmed Ben Kahla, Yousri Elghoul, Achraf Ammar, Liwa Masmoudi, Khaled Trabelsi, Jordan M Glenn, Riadh Dahmen

Summary: As laterality of the lower limbs is regarded as a relevant influence on soccer performance, we assessed whether a bilateral training program for both the preferred leg (PL) and non-preferred leg (NPL) would improve soccer players' lateral asymmetry, agility, and accuracy. Sixty right-foot-dominant young soccer players were randomly assigned to either an experimental group (EXP) that underwent bilateral training or a control group (CONT) that performed their usual training schedule without bilateral exercise. We assessed the players' lateral asymmetries before and after training on four soccer skill tasks: a zigzag test with and without a ball, a receiving and direct volley-shooting accuracy test, and a passing accuracy test. Results showed post-test versus pre-test performance improvements for the EXP group on the index of technical skills and agility (p < .001). A post-hoc analysis further revealed a pre-test to post-test performance improvement on shooting and passing accuracy with both legs only for the EXP group (p < .001). These results support the role of bilateral practice in improving lateral asymmetries, agility, and accuracy.



#9 Melatonin supplementation alleviates cellular damage and physical performance decline induced by an intensive training period in professional soccer players

Reference: PLoS One. 2022 Sep 2;17(9):e0273719. doi: 10.1371/journal.pone.0273719. eCollection 2022.

Authors: Mohamed Amine Farjallah, Kais Ghattassi, Anis Kamoun, Ahmed Graja, Lobna Ben Mahmoud, Tarak Driss, Kamel Jamoussi, Zouheir Sahnoun, Nizar Souissi, Piotr Zmijewski, Omar Hammouda

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Summary: Melatonin has been proved to have positive effects on cellular damage and metabolic regulation. The aim of the study was to determine the effect of melatonin supplementation during an intensive training period on physical performance decline, oxidative stress and cellular damage state. The investigation was conducted on 20 soccer players who participated in an exhaustive six-day training schedule associated with daily 5 mg oral melatonin or placebo ingestion. Resting blood samples and physical performance were measured before and after the training period. The mixed 2-way ANOVA (group x training camp) showed that compared to placebo, melatonin intake prevented an increase in advanced oxidation protein products (p>0.05) and increased the antioxidant enzyme activity (i.e., superoxide dismutase; p<0.001). In addition, melatonin prevented an increase of biomarkers of renal function (e.g., creatinine; p>0.05) and biomarkers of muscle (e.g., creatine kinase; p>0.05) and liver (e.g., gamma-glutamyltransferase; p>0.05) damage. Furthermore, melatonin alleviated the deterioration in physical performance (countermovement jump, five-jump test and 20-m sprint; p>0.05). In conclusion, the obtained data showed increased oxidative stress and renal, muscle and liver damage in professional soccer players during an exhaustive training schedule. Melatonin intake during the training period exerts beneficial effects on physical performance and protects tissues against the deleterious effects of reactive oxygen species and cellular damage.



#10 Inter-limb asymmetries and kicking limb preference in English premier league soccer players

Reference: Front Sports Act Living. 2022 Aug 17;4:982796. doi: 10.3389/fspor.2022.982796. eCollection 2022.

Authors: Gareth Nicholson, Tim Bennett, Aaron Thomas, Lysander Pollitt, Mike Hopkinson, Rubén Crespo, Tom Robinson, Rob J Price

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Summary: The aims of this study were: (1) to quantify interlimb asymmetries in EPL soccer players in the context of kicking limb preference and (2) to establish the relationship between interlimb asymmetries and measures of physical performance. Twenty-two players (age: 21.8 ± 4.4 years) from an EPL club performed a running gait assessment (20 km/h) and unilateral countermovement jumps, a CoD assessment (modified 505 test), and an isokinetic knee extension/flexion protocol using each leg. Asymmetries were quantified using the percentage difference method and Pearson's correlations were used to quantify the association between variables. Players displayed the greatest level of asymmetry in isokinetic strength measures (5.9-12.7%) and lower levels of asymmetry in gait (1.6-7.7%), jump (0.9-7.0%) and CoD (1.9-3.5%) assessments. The influence of the preferred kicking limb was most evident in the isokinetic assessment with the players showing dominance in the preferred limb for knee flexor strength and in the non-preferred limb for knee extensor strength. These manifested in the asymmetry values calculated for the hamstring:quadricep (H:Q) ratios at 60°/s (8.80 ± 7.82%) and 240°/s (11.22 ± 7.04%) and in the functional H:Q ratio (12.67 ± 8.25%). The asymmetry values for peak extensor moment at 240°/s showed a significant correlation (ρ = -0.55, p = 0.034) with 10 m time in the CoD assessment. These findings provide benchmark asymmetry data for soccer practitioners and reveal that kicking limb preferences may bring about interlimb differences in the H:Q ratio which raises important considerations in the design of testing batteries and injury reduction interventions.



#11 Hip arthroscopy is a successful treatment for femoroacetabular impingement in under-16 competitive football players: a prospective study with minimum 2-year follow-up

Reference: Arch Orthop Trauma Surg. 2022 Sep 6.  doi: 10.1007/s00402-022-04584-1. Online ahead of print.

Authors: David Barastegui, Roberto Seijas, Eduard Alentorn-Geli, Alfred Ferré-Aniorte, Patricia Laiz, Ramon Cugat

Summary: Femoroacetabular impingement is considered a spectrum disease affecting multiple hip structures and it is especially prevalent in football players. Hip arthroscopy has shown good results in this population. However, little attention has been given to its efficacy in children and adolescent players. The aim of this study is to evaluate the outcomes of hip arthroscopy in under-16 football players. Between 2008 and 2019, all under-16 competitive football players who underwent hip arthroscopy for the treatment of femoroacetabular impingement were recruited for this prospective study. Hip pain and function were measured through the VAS, HOS, mHHS and WOMAC scores before the surgery, at 1-year after the surgery and at minimum 2-years after surgery. Preoperative and postoperative scores were compared to establish the evolution of hip pain and function