Latest research in football - week 17 - 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 Impact of the Menstrual Cycle Phases on the Movement Patterns of Sub-Elite Women Soccer Players during Competitive Matches

Reference: Int J Environ Res Public Health. 2022 Apr 7;19(8):4465. doi: 10.3390/ijerph19084465.

Authors: Pierre-Hugues Igonin, Isabelle Rogowski, Nathalie Boisseau, Cyril Martin

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Summary: The purpose of this study was to evaluate the influence of the menstrual cycle phases on the movement patterns of sub-elite women soccer players during competitive matches over three consecutive seasons. Individual movement data were analyzed and compared in eight players from the second French League at the early follicular (EF), late follicular (LF) and mid-luteal (ML) phases of their menstrual cycle, determined by the calendar method. The movement patterns, expressed as meters per minute, were recorded during competitive matches using devices placed on the player's ankle. Our results showed significantly lower distances covered at moderate and high velocity in the EF phase than in the LF and ML phases (Cohen's d effect size = 1.03 and 0.79, respectively). The total distance covered during matches and the number of sprints also were reduced during EF compared with LF (d = 0.78 and 0.7, respectively). Overall, the total distance and distance covered at low velocity were significantly lower during the second half-time of the matches (d = 1.51), but no menstrual cycle phase × game period interaction was noted. In conclusion, our study suggests that EF may impact the movement pattern of sub-elite women soccer players during competitive matches, without any modulation of this effect by the playing time. Despite the low sample size, these results can be useful for coaches and support staff to modulate training loads and player rotation during soccer games.



#2 In-Season Microcycle Quantification of Professional Women Soccer Players-External, Internal and Wellness Measures

Reference: Healthcare (Basel). 2022 Apr 7;10(4):695. doi: 10.3390/healthcare10040695.

Authors: Renato Fernandes, Halil İbrahim Ceylan, Filipe Manuel Clemente, João Paulo Brito, Alexandre Duarte Martins, Hadi Nobari, Victor Machado Reis, Rafael Oliveira

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Summary: Although data currently exists pertaining to the intensity in the women's football match, the knowledge about training is still scarce. Therefore, the aim of this study was to quantify external (locomotor activity) and internal (psychophysiological) intensities, as well as the wellness profile of the typical microcycle from professional female soccer players during the 2019/20 in-season. Ten players (24.6 ± 2.3 years) from an elite Portuguese women soccer team participated in this study. All variables were collected in 87 training session and 15 matches for analysis from the 2019-2020 in-season. Global positioning variables such total distance, high-speed running, acceleration, deceleration and player load were recorded as intensity while Rated Perceived Exertion (RPE) and session-RPE were recorded as internal measures. The Hooper Index (HI) was collected as a wellness parameter. The results showed that internal and external intensity measures were greater in matches compared to trainings during the week (match day minus [MD-], MD-5, MD-4, MD-2), p < 0.05 with very large effect size (ES). In the same line, higher internal and external intensity values were found in the beginning of the week while the lowest values were found in MD-2 (p < 0.05, with very large ES). Regarding wellness, there was no significant differences in the HI parameters between the training days and match days (p > 0.05). This study confirmed the highest intensity values during MD and the lowest on the training session before the MD (MD-2). Moreover, higher training intensities were found in the beginning of the training week sessions which were then reduced when the MD came close. Wellness parameters showed no variation when compared to intensity measures. This study confirmed the hypothesis regarding internal and external intensity but not regarding wellness.



#3 External Match Load in Amateur Soccer: The Influence of Match Location and Championship Phase

Reference: Healthcare (Basel). 2022 Mar 22;10(4):594. doi: 10.3390/healthcare10040594.

Authors: Mauro Miguel, Rafael Oliveira, João Paulo Brito, Nuno Loureiro, Javier García-Rubio, Sergio Jose Ibáñez

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Summary: Assessment of the physical dimension implicit in the soccer match is crucial for the improvement and individualization of training load management. This study aims to: (a) describe the external match load at the amateur level, (b) analyze the differences between playing positions, (c) verify whether the home/away matches and if (d) the phase (first or second) of the championship influence the external load. Twenty amateur soccer players (21.5 ± 1.9 years) were monitored using the global positioning system. The external load was assessed in 23 matches, where 13 were part of the first phase of the competition (seven home and six away matches) and the other 10 matches belonged to the second (and final) phase of the championship (five home and five away matches). A total of 173 individual match observations were analyzed. The results showed significant differences between playing positions for all the external load measures (p < 0.001). There were higher values observed in the total distance covered for central defenders (p = 0.037; ES = 0.70) and in high-intensity decelerations for forwards (p = 0.022; ES = 1.77) in home matches than in away matches. There were higher values observed in the total distance (p = 0.026; ES = 0.76), relative distance (p = 0.016; ES = 0.85), and moderate-intensity accelerations (p = 0.008; ES = 0.93) for central defenders, in very high-speed running distance for forwards (p = 0.011; ES = 1.97), and in high-intensity accelerations (p = 0.036; ES = 0.89) and moderate-intensity decelerations (p = 0.006; ES = 1.11) for wide midfielders in the first phase than in the second phase of the championship. Match location and championship phase do not appear to be major contributing factors to influence the external load while the playing position should be used as the major reference for planning the external training load.



#4 Understanding the Relationship between Sport Courage and Female Soccer Performance Variables

Reference: Int J Environ Res Public Health. 2022 Apr 12;19(8):4654. doi: 10.3390/ijerph19084654.

Authors: Erkut Konter, Adam Gledhill, Yee Cheng Kueh, Garry Kuan

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Summary: The purpose of this study was to examine the relationships between female soccer players' courage and key performance variables (level of participation, injury past, being selected or non-selected by a national team, being starter or substitute). The Sport Courage Scale-31, by Konter and Ng (2012) and key performance variables were collected from 210 female soccer players aged 12 to 27 (M = 17.97 ± 3.34 years old). Spearman correlations and Mann-Whitney U tests were used to analyse the collected data. The correlations between mastery (r = 0.196), determination (p = 0.239), assertiveness (r = 0.325), sacrifice behaviour (r = 0.182), total sport courage (r = 0.265) and age of female soccer players were found to be significant (p < 0.05). Female soccer players who have sustained an injury in the past scored significantly higher on the venturesome scale (p = 0.006) than those who have not sustained an injury in the past. In comparison, female soccer players who have not sustained an injury in the past or who have not been substituted had significantly more mastery than female soccer players who have sustained an injury in the past or who have been substituted (p = 0.017, p = 0.002, respectively). This study indicates that sport courage is related to key performance variables among female soccer players. Mastery and age seem to be related to courageous behaviour, whereas increasing venturesomeness might cause injuries in female soccer. Some relevant implications for practitioners can be drawn from the present findings.



#5 Analysis of Intensities Using Inertial Motion Devices in Female Soccer: Do You Train like You Compete?

Reference: Sensors (Basel). 2022 Apr 8;22(8):2870. doi: 10.3390/s22082870.

Authors: Juan M García-Ceberino, Ana Bravo, Ernesto de la Cruz-Sánchez, Sebastián Feu

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Summary: Intensity research in female soccer is limited. This study aimed to investigate whether female professional soccer players train with external and internal intensities similar to those recorded in real competition. The specific players' position, the game situation and training task type were analyzed in a total of 18 female players (26.25 ± 3.89 years). The empirical, descriptive and associative study was structured into two parts. Part 1: characterizing the training sessions (n = 13) and official matches (n = 3) using the Integral Analysis System of Training Tasks. The association between sports planning variables was evaluated using adjusted standardized residuals from contingency tables, Chi-Square and Fisher tests, as well as the Phi and Cramer's V coefficients. The main findings show that the coach and/or physical trainer predominantly planned training sessions using small-sided games, which integrate physical fitness and tactical-technical behaviors of the game and imply a medium-high subjective external intensity (20.63 ± 5.79 points). The subjective external intensity of the matches was very high (30.00 ± 0.00 points). Part 2: quantifying the external and internal intensity through the inertial motion devices and heart rate monitors. Differences in the intensities according to the type of session (training session and match), specific position of the players, game situation and type of the training task were assessed through different statistical tests. By specific position (Kruskal-Wallis H and one-factor ANOVA tests), defenders performed fewer accelerations/min and decelerations/min, while they recorded higher heart rates in training sessions and official matches. In contrast, the wingbacks performed higher accelerations/min and decelerations/min in training sessions and official matches. The wingers had the lowest heart rate in official matches. Regarding the game situation (Kruskal-Wallis H test) measured during training sessions, the unopposed tasks recorded higher accelerations/min and decelerations/min, while the small-sided games and full games recorded higher values in the rest of the intensities (both subjective and objective). With regard to the type of training task (Kruskal-Wallis H test), the simple application exercises recorded higher accelerations/min and decelerations/min. Distance in meters/min was greater in the complex application exercises. High-intensity activity/min and player load/min were higher in the simple specific game. In addition, modified sport and real game recorded higher subjective external intensity*min, sprints/min and heart rate. Furthermore, training sessions differed statistically (Mann-Whitney U test) from official matches in terms of subjective intensity and the objective external and internal intensity variables weighted by minutes. For all these reasons, female players do not train (training sessions) as they compete (official matches). The use of inertial motion devices has made it possible to quantify intensities during training sessions and real competition in soccer.



#6 Mind the gap! A survey comparing current strength training methods used in men's versus women's first team and academy soccer

Reference: Sci Med Footb. 2022 Apr 27. doi: 10.1080/24733938.2022.2070267. Online ahead of print.

Authors: Stephen J McQuilliam, David R Clark, Robert M Erskine, Thomas E Brownlee

Summary: Much less is known about strength and conditioning (S&C) practice in women's versus men's soccer. The aim of this study was to compare S&C practice between coaches working in men's or women's soccer, at first team or academy level, worldwide. A total of 170 participants, who were involved with S&C support at their soccer club (in Europe, USA and South America, within men's or women's first team or academy settings) completed a comprehensive online survey, designed to evaluate (i) their academic qualifications and S&C coaching experience; and their preferred methods for (ii) physical testing; (iii) strength and power development; (iv) plyometric training; (v) speed development; and (vi) periodization. Women's academies had fewer weekly in-season S&C sessions than men's academies (1.6±0.6 vs. 2.3±0.9, p=0.005). Relatively, fewer women's academy S&C coaches (6%) used Olympic weightlifting movements than men's academy S&C coaches (32%, p=0.030). Relatively, more women's academy coaches (47%) used the Nordic hamstring exercise (NHE) compared to men's academy coaches (15%, p=0.006), but relatively more women's vs. men's first team coaches (61% vs. 38%, p=0.028) and women's vs. men's academy (61% vs. 38% coaches, p=0.049) utilised rating of perceived exertion-based load prescriptions. Notable differences in S&C practice exist between coaches of men's and women's soccer squads, particularly at academy level. For example, fewer weekly S&C sessions in women academy players may have implications for physical development, while the greater use of subjective load prescriptions in both academy and first team women's squads may lead to sub-optimal performance gains.



#7 Maximal vs. explosive knee extensor strength in professional soccer players: inter-limb asymmetries and relationship with knee function

Reference: Eur J Sport Sci. 2022 Apr 27;1-19. doi: 10.1080/17461391.2022.2071636. Online ahead of print.

Authors: Victor R A Cossich, Ubiratã F Gavilão, Rodrigo A Goes, Jamila A Perini, Conrado T Laett, Nicola A Maffiuletti

Summary: The main aims of this study were to compare the magnitude of inter-limb asymmetry (ILA) and the relation with self-reported knee function between maximal and explosive knee extensor strength outcomes in professional soccer players. Forty-six male soccer players completed different maximal isokinetic and isometric contractions of the knee extensors for the assessment of maximal strength (peak torque and maximal voluntary contraction (MVC) torque) and explosive strength (early, intermediate, late, and peak rate of torque development (RTD)). Self-reported knee function was assessed with the International Knee Documentation Committee (IKDC) and Lysholm knee scoring scales. Peak torque and MVC torque showed comparable ILAs (8-9%), both being significantly lower than all RTD ILAs (16% on average; p < 0.001). ILAs for early RTD (21%) and peak RTD (19%) were significantly higher than all the other variables (p < 0.05). Only early and intermediate RTD were significantly correlated - though weakly - with both IKDC (rho = 0.32 for both) and Lysholm (rho = 0.36 and 0.30, respectively) scores. We conclude that explosive knee extensor strength - early RTD in particular - exhibited larger ILAs and better relations with self-reported knee function than peak torque and MVC torque in professional soccer players. These results confirm the validity and functional relevance of early RTD and the need for its inclusion in routine performance testing for soccer players.



#8 Effect of ball inclusion on jump performance in soccer players: a biomechanical approach

Reference: Sci Med Footb. 2022 May;6(2):241-247. doi: 10.1080/24733938.2021.1915495. Epub 2021 Apr 22.

Authors: Alberto Fílter, Jesús Olivares Jabalera, Alejandro Molina-Molina, Luis Suárez-Arrones, José Robles-Rodríguez, Thomas Dos'Santos, Irineu Loturco, Bernardo Requena, Alfredo Santalla

Summary: In soccer, vertical jump means jumping toward a ball. Since no vertical jump test includes the ball as a reference element, the effect that the ball would have in a vertical jump test is unknown. The aim of this study was to examine the biomechanical differences between run-up vertical jump measurements without (Run-up Vertical Jump) and with ball inclusion (Heading Test). Twelve semi- and professional soccer players were recruited. Athletes performed both jump tests in a biomechanical laboratory, where kinetic and spatiotemporal variables were collected and compared using a Student's dependent t-test for paired samples. Overall, players performed a different jumping strategy during the heading test compared to the run-up vertical jump, exhibiting: 1) higher horizontal velocity during initial contact (+45.3%, P ≤ .001), 2) shorter contact time, greater rate of force development, and total impulse during push-off (+27.5%, +53%, and +10.6%, respectively, P ≤ .008), 3) higher CoM horizontal and resultant velocity during take-off (+76.1% and 20.5%, respectively, P ≤ .001), 4) better vertical jump performance (+4.3%, P ≤ .0001), and 5) larger body angle rotation during landing (+63.3%, P = .006), compared to run-up vertical jump (effect size: 0.78 to 3.7). In general, soccer players display greater vertical jump heights in heading test, which highlights the importance of including an overhead ball during soccer-specific jump tests. Coaches and practitioners are encouraged to assess, and perhaps develop, the jumping ability of soccer players using a suspended ball as a specific target.



#9 Missing data: current practice in football research and recommendations for improvement

Reference: Sci Med Footb. 2022 May;6(2):262-267. doi: 10.1080/24733938.2021.1922739. Epub 2021 May 26.

Authors: David N Borg, Robert Nguyen, Nicholas J Tierney

Summary: A survey of 136 articles published in 2019 (sampled at random) was conducted to determine whether a statement about missing data was included. The proportion of studies reporting on missing data was low, at 11.0% (95% confidence interval = 6.3% to 17.5%). We recommend that researchers describe the number and percentage of missing values, including when there are no missing values. Exploratory analysis should be conducted to explore missing values, and visualisations describing missingness overall should be provided in the paper, or at least in supplementary materials. Missing values should almost always be imputed, and imputation methods should be explored to ensure they are appropriately representative. Researchers should consider these recommendations and pay greater attention to missing data and its influence on research results.



#10 Neuromuscular control and hop performance in youth and adult male and female football players

Reference: Phys Ther Sport. 2022 Apr 13;55:189-195. doi: 10.1016/j.ptsp.2022.04.004. Online ahead of print.

Authors: Sofi Sonesson, Martin Hägglund, Joanna Kvist, Kalle Torvaldsson, Hanna Lindblom, Anne Fältström

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Summary: The aim was to compare neuromuscular control and hop performance between youth and adult male and female football players. 119 youth players (13-16 years; 68 males) and 88 adult players (17-26 years; 44 males) participated in the investigation. Neuromuscular control assessed with drop vertical jump (DVJ) and tuck jump assessment (TJA). Hop performance assessed with single-leg hop for distance and side hop were assessed. Adult females had smaller normalized knee separation distances (NKSD) during DVJ at initial contact (77.9 ± 18.5 vs. 86.1 ± 11.0, p = 0.010) and at maximum knee flexion (59.7 ± 23.4 vs.74.1 ± 18.1, p = 0.001) compared to youth females. TJA revealed more technique errors in youths compared to adults (males 10 (8-11) vs. 8 (7-10); females 11 (9-12) vs. 9 (8-11), p < 0.05). Youths demonstrated inferior hop performance (males single-leg hop 142 ± 18 vs. 163 ± 17, side hop 41 ± 12 vs. 52 ± 12, p < 0.001; females side hop 32 ± 10 vs. 38 ± 14, p < 0.05). Youth players demonstrated reduced neuromuscular control during TJA and inferior hop performance compared to adult players. Adult female players demonstrated greater knee valgus during DVJ compared to youth female players.



#11 Hamstrings injuries in football

Reference: J Orthop. 2022 Apr 11;31:72-77. doi: 10.1016/j.jor.2022.04.003. eCollection May-Jun 2022.

Authors: André Gismonti Garcia, Renato Andrade, José Afonso, José Luíz Runco, Antonio Maestro, João Espregueira-Mendes

Summary: Hamstrings injuries are a major concern in football (soccer), affecting both recreational players and professional athletes. Although being a recognized issue within the football community, its incidence has been increasing over the last years and still poses a challenge to all practitioners involved. The goal of this narrative review is to outline hamstrings injuries epidemiology and mechanisms of injury, identify and discuss its risk factors, provide an approach to a proper early diagnosis, evaluate the efficacy of current treatment options and return to sports, and present the best strategies for hamstrings injury prevention. These guidelines will help the sports medicine staff team on how to better manage their players with or at risk of hamstrings injuries. Despite several breakthroughs in research of hamstrings injuries, there is still heterogeneity across studies and lack of consensus in regards to classification, diagnosis, treatment and prevention. Hamstrings injuries compromise the athlete's performance with time loss due to injury, shortens their highest-level career longevity with higher risk of reinjury rates, and is a defying problem for clubs to balance financial losses due to having their players off the pitch. Further research is warranted to keep moving forward with evidence on treating and preventing hamstrings injuries to mitigate its high incidence and keep the players safe.



#12 Analysis of the Football Transfer Market Network

Reference: J Stat Phys. 2022;187(3):27. doi: 10.1007/s10955-022-02919-1. Epub 2022 Apr 19.

Authors: Tobias Wand

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Summary: Using publicly available data from the football database, it is possible to construct a trade network between football clubs. This work regards the network of the flow of transfer fees between European top league clubs from eight countries between 1992 and 2020 to analyse the network of each year's transfer market. With the transfer fees as weights, the market can be represented as a weighted network in addition to the classic binary network approach. This opens up the possibility to study various topological quantities of the network, such as the degree and disparity distributions, the small-world property and different clustering measures. This article shows that these quantities stayed rather constant during the almost three decades of transfer market activity, even despite massive changes in the overall market volume.



#13 Tests of rubber granules used as artificial turf for football fields in terms of toxicity to human health and the environment

Reference: Sci Rep. 2022 Apr 23;12(1):6683. doi: 10.1038/s41598-022-10691-1.

Authors: Beata Grynkiewicz-Bylina, Bożena Rakwic, Barbara Słomka-Słupik

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Summary: Rubber waste, in the form of granules of styrene butadiene rubber and ethylene-propylene-diene-monomer with a particle size of 0.5 to 4 mm, is broadly used for the construction of synthetic surfaces of sport fields. This method of recycling may be significantly limited due to the restrictions on polycyclic aromatic hydrocarbons (PAHs) content in rubber granules in the European Union since 2022. This also applies to the recommendations of the European Chemicals Agency in relation to the identification of other hazardous chemicals in this waste, including metal elements. The scope of the research included the identification of organotin compounds, PAHs content and 18 elements leached from recycled rubber granules in terms of substances harmful to human health and to natural environment. The research covered 84 samples of rubber granules collected from the surface of football pitches or supplied by recyclers in Poland. The test results showed an over-standard content of PAHs in rubber granules. This result confirms the need to develop alternative directions of rubber granules application: construction and hydro construction, reinforcing soil and roadsides, asphalt pavements, making retaining walls, anti-shock and anti-vibration slabs, soundproofing and damping screens, paving stones and landscaping elements.



#14 Activity Level and Nature of Practice and Play in Children's Football

Reference: Int J Environ Res Public Health. 2022 Apr 11;19(8):4598. doi: 10.3390/ijerph19084598.

Authors: Tone Nybakken, Coral Falco

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Summary: This study analyzes the activity level and nature of organized football training (deliberate practice, DPR), compared with when children play football on their own (deliberate play, DPL), in a sample of selected (YT) and non-selected (BT) talents. A total of 29 observations were analyzed over 2650 min, focusing on the kind of activity, variability, and intensity of the training. In DPL, there are more finishing on goal, involvement, and challenges in 1:1 situation, and more ball touches and ball transport in games, compared with DPR. Additionally, DPL has more activity time (68% vs. 56%) and fewer breaks overall (32% vs. 44%). In DPL, children spend more time playing against each other (92% vs. 36%), and most of the time there are games or finishing on goal. In DPR, children spend more time playing together with someone (2% vs. 44%) and in passing and receiving the ball. DPR training contains more standardized exercises and protected situations. DPR-YT training differs from DPR-BT training with less activity time, ball touches, attempts on goal, and 1:1 situations. In conclusion, the results support DPL providing more football-specific activity. More DPR training at the expense of DPL might reduce practice time for skill development.



#15 Perceptions of Professional Football Players on Injury Risk Factors and Prevention Strategies

Reference: Sci Med Footb. 2022 May;6(2):148-152. doi: 10.1080/24733938.2021.1937689. Epub 2021 Jun 9.

Authors: Rogério Ferreira Liporaci, Sergio Yoshimura, Bruno Manfredini Baroni

Summary: Considering individual beliefs and preferences is a pillar of the evidence-based practice and determines compliance and outcomes of an intervention. However, little is known about the professional football (soccer) players' perceptions on injury issues. The aim of this study was to describe the professional football players' perceptions towards injury risk factors and prevention strategies. One-hundred male professional football players answered an online questionnaire. The top-five risk factors included poor muscle strength/power; poor rest/sleep; short interval between matches; high number of matches in season; and excessive training. More than ¾ of football players in our study considered the following strategies as being effective in reducing injury risk: workload monitoring; warm-up; lumbo-pelvic stability training; proprioceptive training; functional training; monitoring diet; flexibility training; and conventional strength training. Perceptions of professional male football players regarding injury risk factors and prevention strategies are only partially in line with current scientific evidence. These perceptions have been usually overlooked, and should be considered by medical/coaching staffs in order to get greater compliance to injury prevention programs.



#16 Injury incidence and prevalence in Finnish top-level football - one-season prospective cohort study

Reference: Sci Med Footb. 2022 May;6(2):141-147. doi: 10.1080/24733938.2021.1917775. Epub 2021 May 22.

Authors: Einari Kurittu, Tommi Vasankari, Tuomas Brinck, Jari Parkkari, Olli J Heinonen, Pekka Kannus, Timo Hänninen, Klaus Köhler, Mari Leppänen

Summary: The aim was to investigate the injury characteristics in Finnish male football players. One-season prospective epidemiological study. Data were collected via injury reports from the medical staff and directly from the players using the Olso Sports Trauma Research Center Health Questionnaire. The first team squads of Finnish football league (n = 12 teams, 236 players) participated in this study. Injury incidence was assessed. A total of 541 injuries occurred during the exposure of 62 878 hours. Injury incidence per 1000 exposure hours was 8.6 (30.6 in matches and 3.4 in training). A player sustained on average 2.3 (median 2, range 0-13) injuries during the study. Thigh and ankle were the most commonly injured body parts for acute injuries and hip/groin were the most commonly injured body part for overuse injuries. The median absence time for all injuries was 12 (range 0-107) days, 12 (range 0-107) for acute, and 8 (range 0-61) for overuse injuries. Thigh injuries caused the greatest consequences in terms of absence from full participation (median 5 days, range 0-88). Lower limb muscle injuries were the most prevalent injuries in the study. Collecting data directly from the players enabled to report more injuries compared to what was reported only by the medical staff.



#17 Physical and Mental Fatigue Reduce Psychomotor Vigilance in Professional Football Players

Reference: Int J Sports Physiol Perform. 2022 Apr 27;1-8. doi: 10.1123/ijspp.2021-0387. Online ahead of print.

Authors: Luca Angius, Michele Merlini, James Hopker, Mattia Bianchi, Francesco Fois, Francesco Piras, Paolo Cugia, James Russell, Samuele Maria Marcora

Summary: Professional football players experience both physical and mental fatigue (MF). The main aims of this randomized crossover study were to investigate the effect of MF on repeated-sprint ability (RSA) and the effects of both physical fatigue and MF on psychomotor vigilance. Seventeen male professional football players performed 10 maximal 20-m shuttle sprints interspaced by incomplete recovery (RSA test). Running speed, heart rate, brain oxygenation, and rating of perceived exertion were monitored during each sprint. The RSA test was preceded by either a 30-minute Stroop task to induce MF or by watching a documentary for 30 minutes (control [CON]) in a randomized counterbalanced order. Participants performed a psychomotor vigilance test at baseline, after the cognitive task (MF or CON), and after the RSA test. Heart rate and rating of perceived exertion significantly increased, while running speed and brain oxygenation significantly decreased over the repeated sprints (P < .001) with no significant differences between conditions. Response speed during the psychomotor vigilance test significantly declined after the Stroop task but not after CON (P = .001). Response speed during the psychomotor vigilance test declined after the RSA test in both conditions (P < .001) and remained lower in the MF condition compared to CON (P = .012). MF does not reduce RSA. However, the results of this study suggest that physical fatigue and MF have negative and cumulative effects on psychomotor vigilance. Therefore, strategies to reduce both physical fatigue and MF should be implemented in professional football players.



#18 Recovery During a Congested Schedule and Injury in Professional Football

Reference: Int J Sports Physiol Perform. 2022 Apr 28;1-8. doi: 10.1123/ijspp.2021-0504. Online ahead of print.

Authors: Benoit Delaval, Abd-Elbasset Abaïdia, Barthélémy Delecroix, Franck Le Gall, Alan McCall, Said Ahmaidi, Gregory Dupont

Summary: The aim was to analyze the relationships between the recovery kinetics experienced by professional football players and noncontact injury. A cohort of 46 professional football players (age 24.2 [4.7] y) from the same team (French Ligue 1) was monitored each day between matches when the team played twice a week. The recovery monitoring procedure was implemented after 38 matches and included some questionnaires: duration of sleep, Hooper scale (quality of sleep, level of stress, fatigue, and muscle soreness), perceived recovery status scale, creatine kinase concentrations, a countermovement jump, and an isometric force test. Noncontact injuries were collected during these periods. Noncontact injuries were associated with perceived fatigue and muscle soreness 2 days (relative risk [RR] = 1.89 and 1.48, respectively) and 3 days following the matches (RR = 2.08 and 2.08, respectively). An increase of sleep quantity during the 2 nights following a match was significantly associated with a lower RR (RR = 0.65), as well as a lower decrement score on the isometric force test on each of the 3 days after the matches (RR = 0.97, RR = 0.99, and RR = 0.97, respectively). No other association was reported for the variables sleep quality, stress, perceived recovery, creatine kinase concentrations, countermovement jump, and noncontact injuries. During a congested schedule, implementing a recovery monitoring protocol including questionnaires about fatigue, muscle soreness, quantity of sleep, and a physical test of isometric force could help practitioners prevent injuries.



#19 Multi-hosting UEFA European Football Championship: Fair enough between participating teams?

Reference: Sci Med Footb. 2022 Apr 29. doi: 10.1080/24733938.2022.2072944. Online ahead of print.

Authors: Franck Brocherie, Quentin De Larochelambert, Grégoire P Millet

Summary: The aim was to describe the effects of travel distance and bio-meteorological conditions on the 2020 multi-hosting UEFA European Championship's match outcomes and progress in competition. Teams' basecamps, distance from match venues, match outcomes (defeat, draw and win), bio-meteorological data (ambient air temperature, relative humidity and wet bulb globe temperature) and corresponding FIFA world ranking were extracted from the official UEFA and FIFA websites, respectively; and analyzed through Chi-squared test (impact of basecamp location on match outcomes), Kruskal-Wallis test (distribution of travel distances carried out according to match outcomes and competition phases), ordinal regressions (with match outcomes and competition phases as variables of interest and FIFA ranking and venue distance as explanatory variables) and principal component analysis with the bio-meteorological conditions and match outcomes for each match. Teams with basecamp near match venue improved their match outcomes. However, neither Kruskal-Wallis test (p > 0.05) nor ordinal regressions (odds ratio (OR) > 0.96, p > 0.403) identified any significant effect of travel distance on match outcomes. Besides, FIFA ranking improved the likelihood of a favorable match outcome (OR = 0.87, p = 0.001) and progression in competition (OR = 0.97, p = 0.003). Further, despite some matches were played in more stressful bio-meteorological conditions, this was not associated with match outcomes (r = -0.07 to 0.19, p > 0.188). These findings cannot conclusively clarify on the effects of travel and bio-meteorological conditions on match outcomes and progress in the multi-hosting UEFA European championship, but suggest to carefully consider these variables for future multi-hosting competition to avoid any discrepancies between teams.



#20 Association between SARS-COV-2 infection and muscle strain injury occurrence in elite male football players: a prospective study of 29 weeks including three teams from the Belgian professional football league

Reference: Br J Sports Med. 2022 Apr 29;bjsports-2021-104595. doi: 10.1136/bjsports-2021-104595.

Authors: Evi Wezenbeek, Sander Denolf, Tine Marieke Willems, Dries Pieters, Jan G Bourgois, Renaat M Philippaerts, Bram De Winne, Matthias Wieme, Robbe Van Hecke, Laurence Markey, Joke Schuermans, Erik Witvrouw, Steven Verstockt

Summary: The aim of this study was to investigate the association between SARS-CoV-2 infection and muscle strain injury in elite athletes. A prospective cohort study in three Belgian professional male football teams was performed during the first half of the 2020-2021 season (June 2020-January 2021). Injury data were collected using established surveillance methods. Assessment of SARS-CoV-2 infection was performed by a PCR test before each official game. Of the 84 included participants, 22 were infected with SARS-CoV-2 and 14 players developed a muscle strain during the follow-up period. Cox's proportional hazards regression analyses demonstrated a significant association between SARS-CoV-2 infection and the development of muscle strain (HR 5.1; 95% CI 1.1 to 23.1; p=0.037), indicating an increased risk of developing muscle strains following SARS-CoV-2 infection. All athletes who sustained a muscle strain after infection were injured within the first month (15.71±11.74 days) after sports resumption and completed a longer time in quarantine (14.57±6.50 days) compared with the infected players who did not develop a muscle strain (11.18±5.25 days). This study reported a five times higher risk of developing a muscle strain after a SARS-CoV-2 infection in elite male football players. Although this association should be examined further, it is possible that short-term detraining effects due to quarantine, and potentially pathological effects of the SARS-CoV-2 infection are associated with a higher risk of muscle strain injury.



#21 Modeling Players' Scanning Activity in Football

Reference: J Sport Exerc Psychol. 2022 Apr 25;1-9. doi: 10.1123/jsep.2020-0299. Online ahead of print.

Authors: Marius Pokolm, Robert Rein, Daniel Müller, Stephan Nopp, Marie Kirchhain, Karl Marius Aksum, Geir Jordet, Daniel Memmert

Summary: The purpose of this study was to develop and test models of scanning activity in football. Gibson's ecological approach of visual perception and exploratory activity provided the theoretical framework for the models. The video-based data analysis consisted of 17 selected matches and 239 players of the Union of European Football Associations (UEFA) U17 and U19 European Championship 2018 and the UEFA U17 and U21 European Championship 2019. The results showed a positive relation between scanning frequency and successful passes, as well as changes in body orientation. Scanning frequency was also related to a player's appearances in national teams and to opponent pressure. Opponent pressure had a large effect on pass result and the player's body orientation. Previous research on the relation between scanning frequency and performance was extended by several contextual predictors. Future research should focus on gaining a deeper understanding of the relation between scanning frequency and further contextual variables related to scanning.



#22 Exploring Factors Related to Goal Scoring Opportunities in Professional Football

Reference: Sci Med Footb. 2022 May;6(2):181-188. doi: 10.1080/24733938.2021.1931421. Epub 2021 Jun 8.

Authors: Emiel Schulze, Ross Julian, Tim Meyer

Summary: Outscoring opponents is the primary goal in football. To optimise goal scoring opportunities (GSOs), it is important to understand the preceding physical and tactical performance. This observational study explored whether running behaviour prior to GSOs related to the subsequent outcome (goal or no goal) or contextual factors. Tracking data was collected from one professional team during its 2016/2017 season. Physical output was differentiated for attacking styles and analysed for attackers (taking shots) and defenders (trying to prevent shots). Counter attacks were found most effective, as outcomes improved with fewer defenders behind the ball (r=-0.27; p=0.03). Offensively, running behaviour in the minute prior to GSOs explained most variance and increased activities correlated with success (r=0.26; p=0.04). Moreover, decreased high-intensity distances covered during matches significantly correlated with favourable outcomes (r=-0.21; p=0.02). Finally, increased attacking effectiveness was found to relate to greater defensive covered distances (r=0.51; p<0.01). Running behaviour prior to GSOs was found to relate to the subsequent outcome. Specifically, space ahead of attackers, forcing defenders to cover more ground, was found to relate to GSO effectiveness. The running behaviour of attackers was found unrelated to previous activity, highlighting the significance of physical capacity and well-timed substitutions.


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