Latest research in football - week 25 - 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 Can high-intensity interval training and small-sided games be effective for improving physical fitness after detraining? A parallel study design in youth male soccer players

Reference: PeerJ. 2022 Jul 1;10:e13514. doi: 10.7717/peerj.13514. eCollection 2022.

Authors: Filipe Manuel Clemente, Yusuf Soylu, Ersan Arslan, Bulent Kilit, Joel Garrett, Daniel van den Hoek, Georgian Badicu, Ana Filipa Silva

Download link:

Summary: 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. This study followed a randomized parallel study design. Forty male soccer players (age: 16.4 ± 0.5 years old) were assessed three times: (i) baseline; (ii) after 4 weeks of detraining; and (iii) after a retraining period of 4 weeks. After returning from detraining, players were randomized to an SSG-based training intervention (n = 20) or running-based HIIT (n = 20). Interventions lasted 4 weeks, with a training frequency of three sessions per week. At all timepoints, players were assessed by: (i) anthropometry (height, body mass, fat mass (FM)), countermovement jump (CMJ), standing broad jump (SBJ), triple hop jump (THJ), linear sprint test (5-, 10-, and 20-m), zig-zag test with (ZZwB) and without (ZZwoB) ball, three corner run test (3CRT), Y-balance test and the Yo-Yo intermittent recovery test level 1 (YYIRT). Mixed ANOVA (time * group) was conducted for testing interactions between the three timepoints of repeated measures and the two groups. Effect size (ES) for pairwise comparisons was calculated using Cohen's. Between-group analysis revealed significantly smaller SBJ (t = -2.424, p = 0.020, d = -0.767 small ES) and THT (t = -4.353, p < 0.001, d = -1.376 large ES) in the SSG group after the retraining period. At the same time, SSG presented significantly greater FM after retraining compared to HIIT (t = 3.736, p < 0.001, d = 1.181 large ES). Additionally, SSG had significantly smaller values than HIIT in the ZZwB (t = -3.645, p < 0.001, d = -1.153 large ES), but greater times in the ZZwoB (t = 2.679, p = 0.011, d = 0.847 large ES) and 3CRT (t = 3.126, p = 0.003, d = 0.989 large ES). Although SSG and HIIT interventions improved physical fitness outcomes after a period of detraining, they were not able to effectively restore body composition, CMJ, 20-m sprint, ZZwB, and YYIRT compared with the baseline assessments (before detraining). Only HIIT was significantly effective for restoring SBJ, short linear sprin speed, and change-of-direction compared with baseline. HIIT was also significantly better than SSG in improving SBJ and ZZwoB. Although the small sample, the non determination of maturation status and the need to be cautious regarding generalization, HIIT appears to be more beneficial than SSG after a detraining period for recovery of body composition and physical fitness qualities in this specific context of youth soccer players.



#2 Match activity profile and heart rate responses of top-level soccer referees during Brazilian National First and Second Division and regional championships

Reference: Sci Med Footb. 2022 Jul 5. doi: 10.1080/24733938.2022.2098372. Online ahead of print.

Authors: Juliano Fernandes da Silva, Anderson Santiago Teixeira, Jolmerson De Carvalho, Paulo do Nascimento Salvador, Carlo Castagna, Arthur Pereira Ventura, José Francisco de Sousa Neto Segundo, Luiz Guilherme Antonacci Guglielmo, Ricardo Dantas De Lucas

Summary: This study aimed to examine the differences in physical match activities and heart rate (HR) responses experienced by Brazilian field referees (FRs) and assistant referees (ARs) during official matches from three different championship levels (Serie A, Serie B and Regional). The sample was composed of 51 FRs (age: 36.3 ± 4.7 years) and 87 ARs (age: 35.0 ± 5.6 years). Match activities derived from Global Position System and HR response (expressed as average %HRmax) were collected during official soccer matches (91 and 146 individual observations for FRs and ARs, respectively). FRs and ARs covered higher distances at high-intensity running (HIR; d = 1.17 and 2.53, p < 0.001), sprinting (d = 0.82 and 0.48, p < 0.005) and high-intensity activities (HIA; d = 1.07 and 1.97, p < 0.001) in Serie A and Serie B than in Regional. Changes in the distances covered at HIR (0.80 < d < 3.25, p < 0.005), sprinting (d = 0.42, p = 0.050), and HIA (0.93 < d < 3.01, p < 0.005) from one half-match to the other were observed only in Serie A and Serie B for FRs and ARs. The average %HRmax was progressively increased in both half-matches for FRs (1.28 < d < 3.05, p < 0.003) and ARs (0.85 < d < 3.54, p < 0.001) during all championships. Serie A and Regional elicited higher average %HRmax (0.80 < d < 1.37, p < 0.030) than Serie B in FRs. For ARs, Serie A and Serie B elicited higher average %HRmax (2.14 < d < 3.87, p < 0.001) than Regional. In conclusion, the physical match activities and average %HRmax of Brazilian FRs and ARs differ across soccer championship levels. Thus, FRs and ARs require specific training for different championship levels. In particular, FRs and ARs acting in Regional soccer championships are likely to need specific preparation to support the higher physical demand observed at higher competition levels.



#3 What Factors Discriminate Young Soccer Players Perceived as Promising and Less Promising by Their Coaches?

Reference: Res Q Exerc Sport. 2022 Jul 8;1-9. doi: 10.1080/02701367.2022.2088675. Online ahead of print.

Authors: Chellsea Hortêncio Alcântara, João Cláudio Machado, Rodrigo Mendonça Teixeira, Mateus Rossato, Anderson Santiago Teixeira, Juliano Fernandes da Silva

Summary: This study aimed to verify whether there are differences in physical, technical, and tactical assessment outcomes derived from field-based tests and small-sided games (SSG) in addition to anthropometric and maturational characteristics between players classified as promising and less promising as per the coaches' perception. A total of 53 male U-15 youth soccer players (age: 14.8 ± 0.2 years, weight: 61.7 ± 6.9 kg, height: 171.8 ± 6.7 cm) and three experienced coaches from three distinct sports clubs were enrolled in this study. Based on the coaches' perception, players were split into three group levels for both short- and long-term success ranking: (i) promising (PL; top 5 players; n = 15), (ii) intermediate (IL; n = 23) and (iii) less promising (LPL; 5 bottom players; n = 15). The following measures were determined: anthropometry, maturity offset, vertical jump, and aerobic-anaerobic running performance, soccer- specific skills tests, GPS-based running metrics, technical and tactical actions during SSG, and minutes played throughout the season. There were no differences between groups for anthropometrical, maturational, and physical outcomes. PL players in both rankings covered more distances at sprinting and presented more offensive technical and tactical actions during SSG than their LPL peers. PL and IL presented more minutes played in competitive seasons than LPL of short-term ranking. The biggest differences between the players ranked by their coaches were apparent only during a representative game task, emphasizing the importance of SSG as a tool to assess the players' technical-tactical awareness. In addition to the SSG, the coach's eye plays a key role during the talent identification and selection process.



#4 When and How do Professional Soccer Players Experience Maximal Intensity Sprints in Laliga?

Reference: Sci Med Footb. 2022 Jul 8. doi: 10.1080/24733938.2022.2100462. Online ahead of print.

Authors: José M Oliva-Lozano, Víctor Fortes, Roberto López-Del Campo, Ricardo Resta, José M Muyor

Summary: This study aimed to 1) examine the periods in which maximal intensity sprints occurred during professional soccer matches and 2) analyze the maximal intensity sprints registered in match play considering the effect of playing position and other contextual variables. A total of 1252 match observations were collected from 277 male professional soccer players. Sprinting actions at maximal intensity were analyzed during 30 official matches, and both contextual and performance variables were collected using electronic performance and tracking systems. Maximal intensity sprints were more frequent in the first and last periods of the match (0'-15'; 75'-90'), regardless of the playing position (χ2=23.01; p=0.29; ES=0.07). These sprints were usually non-linear actions without possession of the ball and had different tactical purposes depending on the playing position. In addition, regarding the physical performance required by maximal intensity sprints, that the mean sprint duration ranged from ~4.9 s to ~9 s, the mean distance covered ranged from ~30 m to ~55 m, while the mean maximum velocity was between ~30.12 and ~32.80 km/h depending on the tactical purpose and playing position. In conclusion, professional soccer players need to be prepared during warm-ups for maximal intensity sprints in the first period of the match as well as maximal intensity sprints under high fatigue conditions given the frequency of sprints in the last period of the match. Also, training drills should be designed with a special focus on non-linear sprints without possession of the ball, based on the main tactical purpose of each position (e.g., CD: interceptions; MF: recovery runs; FB, WMF and FW: run the channel).



#5 Pelvic region bone density, soft tissue mass, and injury frequency in female professional ballet dancers and soccer athletes

Reference: Sports Med Health Sci. 2021 Aug 12;3(3):157-164. doi: 10.1016/j.smhs.2021.08.002. eCollection 2021 Sep.

Authors: Hamed Vahedi, Carter M Taft, Joshua R Daum, Sherif Dabash, Patrick C McCulloch, Bradley S Lambert

Download link:

Summary: We recently observed a high prevalence of low pelvic bone mineral density (BMD) in female professional ballet performers. Because this population is susceptible to musculoskeletal overuse injuries, we aimed to determine which regions of the pelvis may be at greatest risk compared to general population females (GENPOP) as well as professional female soccer players (SOCCER, a comparison to other elite athletes regularly subjected to high degrees of loading). Three groups of age-matched females [(GENPOP; n = 38, 27±1yrs), (BALLET; single company, n = 36, 26±3yrs), (SOCCER; single NWSL® club, n = 34, 25±1yrs)] consented to have their BMD and body composition assessed (DEXA, GE®). In addition to soft tissue and total and regional BMD analyses, a segmental analysis of the pelvis was performed to determine site-specific BMD for the iliac fossa, iliac fossa/iliac crest/ilium combined, pubic bone, ischium, and sacrum. A mixed-model ANOVA followed by a Tukey's post-hoc test was used to compare the groups (Type-I error; α = 0.05). The BALLET group had lower pelvic BMD for all measures (Avg.%Diff. = 15%-27%, p<0.001) compared to the SOCCER group and for the ischium (Avg.%Diff.= 8%; p=0.007) and sacrum (Avg.%Diff. = 7%; p = 0.028) compared to the GENPOP group. The BALLET group had lower lean mass for all measures compared to the other groups (Avg.%Diff. = 12%-18%; p < 0.01). Professional ballet performers exhibit reduced pelvic region soft tissue and site-specific BMD not previously detected using standard DEXA analyses. These findings highlight which pelvic regions may benefit from preventative strength training and/or nutritional interventions.



#6 Immediate effect of stabilization exercises versus conventional exercises of the trunk on dynamic balance among trained soccer players

Reference: Hong Kong Physiother J. 2022 Jun;42(1):23-30. doi: 10.1142/S1013702522500032. Epub 2021 Dec 31.

Authors: Cyanna Joseph D'souza, Haripriya Santhakumar, Bhaskara Bhandary, Abhishek Rokaya

Download link:

Summary: 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 authors have previously reported that dynamic balance was improved by a 12-week and 6-week TSE program. However, there is a dearth of research on its immediate effect on dynamic balance in trained soccer players. The aim was to compare the immediate effect of TSE with that of CTE on dynamic balance in trained soccer players. Forty-eight male soccer players (24.60 ± 1.38 years) participated in this crossover study, wherein each participant took part in three exercise sessions: TSE, CTE, and No Exercise control (NE), each consisting of three steps: pre-test, intervention and post-test, with an interval of one week between each exercise condition. To assess dynamic balance, the Y Balance Test-Lower Quarter (YBT-LQ) score in the anterior, posteromedial, and posterolateral directions was measured before and 5 minutes after each intervention. The YBT-LQ composite score was significantly improved after TSE (0.51) as compared to CTE (0.22) and NE (0.04) (p<0.05). Furthermore, in TSE and CTE conditions, YBT-LQ scores of the posterolateral and posteromedial directions significantly improved at the post-test (p<0.05). Both TSE and CTE are effective in immediately improving dynamic balance; however, TSE showed greater improvement as compared to the latter. Immediate improvements in the posteromedial and posterolateral directions of the YBT-LQ were demonstrated after performing the TSE and CTE.



#7 Changes in markers of body composition of professional male soccer players during pre-season

Reference: Sports Med Health Sci. 2020 Sep 6;2(3):166-171. doi: 10.1016/j.smhs.2020.08.004. eCollection 2020 Sep.

Authors: Gary Paul McEwan, Franchek Drobnic, Antonia Lizarraga, Antonio Gómez Díaz, Eduard Pons, Antonio Dello Iacon, Viswanath Unnithan

Download link:

Summary: To evaluate changes achieved in whole-body and regional (upper limbs, lower limbs, and trunk) estimates of body composition, twenty professional male soccer players (7 defenders, 7 midfielders, 6 forwards) underwent dual-energy x-ray absorptiometry (DXA) analysis at the beginning and end of pre-season. Measures included: mass, fat mass (FM), fat-free mass (FFM), and body fat per cent (BF%). Players' activity during on-field training sessions was monitored using Global Positioning System (GPS) units, with GPS data used to obtain estimations of energy expenditure (EE). Whole-body mass remained unchanged across the pre-season. Moderate significant increases and decreases were achieved in whole-body FFM (Pre: 59.58 ± 5.27 kg; Post: 60.61 ± 5.18 kg; p = 0.001; d = 0.87) and FM (Pre: 10.60 ± 1.88 kg; Post: 9.56 ± 1.81 kg; p = 0.001; d = 0.85), respectively. Moderate significant decreases were achieved in whole-body BF% (Pre: 14.4 ± 2.3%; Post: 12.9 ± 2.0%; p < 0.001; d = 0.94). No significant inter-positional differences were observed for the changes achieved in any global or regional estimate of body composition. Total EE was significantly correlated with ΔFM (r = 0.65, p = 0.002), ΔFFM (r = 0.46, p = 0.03), and ΔBF% (r = 0.67, p = 0.002). The total EE of pre-season training accounted for 42%, 21%, and 45% of the variance in ΔFM, ΔFFM, and ΔBF%, respectively. These findings suggest that the pre-season period is a suitable time for initiating favourable alterations in body composition following the off-season in elite soccer players.



#8 Identifying the best strategy for soccer penalty success: A predictive model for optimising behavioural and biomechanical trade-offs

Reference: J Biomech. 2022 Jun 23;141:111208. doi: 10.1016/j.jbiomech.2022.111208. Online ahead of print.

Authors: Andrew H Hunter, Theodore P Pavlic, Michael J Angilletta, Robbie S Wilson

Summary: Success in a soccer penalty can be the difference between winning and losing matches. The outcome is determined by a complex interaction between the shooter and goalkeeper, whose performances are constrained by biomechanical trade-offs. To overcome these performance constraints, each player has a range of available strategies. Shooters can kick at different speeds, affecting accuracy, while goalkeepers can move at various times (leave-times), affecting the time available to move and the probability they move in the correct direction. Previous models of penalty success ignore such trade-offs and how they interact to influence the outcome. Here, we present a model that accounts for shooting inaccuracy to predict the probability of success for all shooting strategies, defined as any combination of: shot speed, position where the shooter aims, shooter footedness, and kicking technique (side-foot or instep). To estimate the probability of success each shooting strategy is matched against all possible goalkeeper leave-times, considering the probability each leave-time is chosen. We test the model against an average goalkeeper and a goalkeeper who tends to move later. Against the average goalkeeper, aiming on the ground toward the centre of the goal is optimal; however, against a late moving goalkeeper, aiming on the ground to the extremities of the goal is effective, with the optimal target in the horizontal dimension dependent on shot speed, kick technique, and footedness. Coaches could use this model to identify their best penalty takers and each players' optimal shooting strategy against either the average goalkeeper or a specific goalkeeper.



#9 Deciphering the offensive process in women's elite football: a multivariate study

Reference: Scand J Med Sci Sports. 2022 Jul 8. doi: 10.1111/sms.14206. Online ahead of print.

Authors: Rubén Maneiro, I Iván-Baragaño, José L Losada, Antonio Ardá

Summary: Over the last few years there has been considerable increase in scientific knowledge about women's football. However, the tactical and tactical-strategic aspects have not yet been sufficiently covered in scientific literature. Therefore, this work proposed the following aims: to describe how the offensive phase is produced in women's football, to identify the significant statistical criteria that may be modulating success in attack, and finally to propose different predictive success models, with the ultimate aim of passing this knowledge on to the applied field. The observational methodology was used, one of the most appropriate methodologies for the analysis of motor behaviors in sport. The units of analysis collected and analysed were 6,063 attacks carried out during the FIFA Women's World Cup Canada 2015 and France 2019. The available results demonstrate that, on the one hand, offensive team actions are ineffective (almost 70% finish unsuccessfully), but criteria such as the start form of the attack, zone of ball possession, partial match result or ball possession time are statistically significant criteria that modulate attack success (goal, shot or pass into the area). Lastly, the multivariate results allow us to propose a theoretical model, passing the probability of success from 31% in the absence of a model, to a theoretical auction probability of 52.6%, based on fast attacks with the intervention of few players, and with possession zone in the opposite field. These results could be directly transferred to the practical field where trainers and technical bodies can put this information into practice in training sessions or matches.



#10 Evaluation of Football Teaching Quality Based on Big Data

Reference: Comput Math Methods Med. 2022 Jun 28;2022:7174246. doi: 10.1155/2022/7174246. eCollection 2022.

Authors: Yue Long, Wei Zhai

Download link:

Summary: The arrival of the big data era has opened up new avenues for assessing the quality of physical education instruction. Using big data to explore these systems may help improve the quality of physical education itself, in addition to assisting schools in developing quality assessment systems for physical education. More and more schools are making football a compulsory part of their physical education and wellness curriculum. Therefore, this study used the methods of literature materials, expert interviews, questionnaires, and Delphi method to determine the evaluation indicators and index weight coefficients of football teaching and borrowed the application background of big data to initially explore the construction of a football teaching quality evaluation system. To this end, this paper completes the following tasks: (1) The current state of football teaching quality evaluation studies in the United States and internationally is summarized. (2) A football teaching quality evaluation system based on the background of big data is constructed. (3) Our experiments show that the assessment approach described in this study is scientifically and rationally distributed and can accurately represent all components of physical education. As a result, evaluating football instruction using big data is a possibility.



#11 Analysis of defensive playing styles in the professional Chinese Football Super League

Reference: Sci Med Footb. 2022 Jul 7. doi: 10.1080/24733938.2022.2099964. Online ahead of print.

Authors: Lingfeng Ruan, Huanmin Ge, Miguel-Ángel Gómez, Yanfei Shen, Bingnan Gong, Yixiong Cui

Summary: Describing and measuring different team styles of play during matches is a key step towards a more predictive and prescriptive performance analysis. The current study aimed to identify and measure different defensive playing styles in professional football via Principal Component Analysis (PCA). The sample comprised all 240 matches played in the Chinese Football Super League (CSL) during the 2018 season. Seventeen key performance indicators (KPIs), 15 defense-related and 2 physical-related were identified from sixty-two defensive performance indicators. Those metrices were significantly different between when teams lost and did not lose (p<0.05, ES=0.03-0.22). The value of Kaiser-Meyer-Olkin for KPIs was 0.81. Then PCA model based on 17 KPIs outputted eight principal factors representing 7 different styles of play (factor 6 and 8 represented one style) and explaining 83.01% of the total variance. Of all styles, defense close to own goal, which included clearance, ball gain in the zone 1, deep completion and unsuccessful cross of the opponent, was the most dominant style (31.92% of the total variance). The champion of the league (Shanghai SIPG FC) showed better scores in all styles of play, while the last ranked team (Guizhou Hengfeng) got the highest score in defense close to the own goal. The study indicated that a team's defensive style could be defined by specific KPIs, and teams are suggested to attune their defending styles consciously rather than maintaining a consistent strategy so as to achieve better performance. Moreover, the categorization of defensive styles could be used during scouting and match preparation.



#12 Influence of Different Passing Methods of Physical Fitness in Football Using Deep Learning

Reference: Comput Intell Neurosci. 2022 Jun 25;2022:8242164. doi: 10.1155/2022/8242164. eCollection 2022.

Authors: Shuai Wang, Xia Zhao

Download link:

Summary: Deep learning is a new direction in the field of machine learning, which learns the inherent laws and levels of data sample representation. The information gained during learning plays an important role in interpreting data such as text, images, and speech. This paper aims to study how to analyze and study the physical energy consumption of passers and receivers in different passing methods in football based on deep learning. This paper proposes the problem of physical energy consumption, which is based on deep learning, then elaborates on the concept of deep learning and related algorithms, and designs and analyzes the case of physical energy consumption of athletes. The experimental results showed that the average heart rhythm (184.35) of the subjects in the first and third experiments was more than twenty points higher than the average heart rhythm (159.85) of the kickers in the second and fourth experiments. Different passing styles have significantly different effects on the physical energy expenditure of players and defensive receivers.



#13 Characterizing player's playing styles based on player vectors for each playing position in the Chinese Football Super League

Reference: J Sports Sci. 2022 Jul 6;1-12. doi: 10.1080/02640414.2022.2096771. Online ahead of print.

Authors: Yuesen Li, Shouxin Zong, Yanfei Shen, Zhiqiang Pu, Miguel-Ángel Gómez, Yixiong Cui

Summary: Characterizing playing style is important for football clubs on scouting, monitoring and match preparation. Previous studies considered a player's style as a combination of technical performances, failing to consider the spatial information. Therefore, this study aimed to characterize the playing styles of each playing position in the Chinese Football Super League (CSL) matches, integrating a recently adopted Player Vectors framework. Data of 960 matches from 2016-2019 CSL were used. Match ratings, and 10 types of match events with the corresponding coordinates for all the line-up players whose on-pitch time exceeded 45 minutes were extracted. Players were first clustered into eight positions. A player vector was constructed for each player in each match based on the Player Vectors using Nonnegative Matrix Factorization (NMF). Another NMF process was run on the player vectors to extract different types of playing styles. The resulting player vectors discovered 18 different playing styles in the CSL. Six performance indicators of each style were investigated to observe their contributions. In general, the playing styles of forwards and midfielders are in line with football performance evolution trends, while the styles of defenders should be reconsidered. Multifunctional playing styles were also found in high-rated CSL players.



#14 The effect of physical fatigue on the performance of soccer players: A systematic review

Reference: PLoS One. 2022 Jul 14;17(7):e0270099. doi: 10.1371/journal.pone.0270099. eCollection 2022.

Authors: Felipe Dambroz, Filipe Manuel Clemente, Israel Teoldo

Download link:

Summary: This study aimed to carry out a systematic review to analyze, describe and discuss the effect of physical fatigue on the performance of soccer players. For this systematic review, searches were performed in Pubmed, Web of Science and SPORTDiscus electronic database until October 3, 2020, following the guidelines of PRISMA. A total of 12 articles met the inclusion criteria: i) healthy soccer players from any age group, competitive level or sex; ii) exposure to physical fatigue; iii) pre and post-physical fatigue conditions; iv) players' cognitive, technical, physical and tactical performances and v) no restrictions regarding the study design. The results section was organized in four main dimensions: cognitive, technical, physical and tactical. Studies on cognitive performance have shown divergent results, varying according to the cognitive task employed and the physical protocol used. Regarding technical performance, negative effects of physical fatigue were found on the technical fundamentals of the pass, dribble and kick. With regard to physical performance, studies have shown a reduction in sprint capacity and distances covered at high velocity. Finally, the only study that analyzed the tactical performance in the field showed an increase in the team's collective tactical behavior, but did not include analysis of the players' individual tactical actions. In summary, the results of the analyzed studies show that the effect of physical fatigue on cognitive performance is inconclusive and that technical and physical performance are negatively affected. Regarding tactical performance, there is a lack of information on the topic in the current literature.



#15 Carbohydrate fear, skinfold targets and body image issues: A qualitative analysis of player and stakeholder perceptions of the nutrition culture within elite female soccer

Reference: Sci Med Footb. 2022 Jul 14. doi: 10.1080/24733938.2022.2101143. 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 the role of nutrition in supporting player development and performance in elite female soccer. Semi-structured interviews (36 ± 18 mins in length) 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 provided an insight into the nutrition culture within elite women's soccer. Data demonstrate that considerable confusion and misconceptions exist amongst players and stakeholders regarding the theoretical underpinning and practical application of meeting energy requirements, colloquially referred to as "fuelling". As such, it is perceived that players "under-fuel", which is likely caused by misunderstandings about the impact of carbohydrate intake on body composition, a fear of weight gain and the associated impacts upon body image. The "carbohydrate fear" that is experienced by players is exacerbated by external pressures arising from social media, key stakeholders (e.g., coaches) and the skinfold culture surrounding measurement of body composition. Such cultural issues are amplified by the lack of full-time professionally accredited nutritionists overseeing the provision of nutrition support. Indeed, the infrastructure supporting the women's game (e.g. staffing resource, on-site food provision, player education programmes etc.) was considered incomparable to the men's game. When taken together, our data provide a platform for which to develop organisational, stakeholder and player centred education and behaviour change interventions that strive to promote a positive performance nutrition culture within the women's game.



#16 Aerobic capacity of professional soccer players before and after COVID-19 infection

Reference: Sci Rep. 2022 Jul 13;12(1):11850. doi: 10.1038/s41598-022-16031-7.

Authors: Koulla Parpa, Marcos Michaelides

Download link:

Summary: This investigation aimed to assess the aerobic capacity of professional soccer players pre-and post-COVID-19 infection. Twenty-one division-1 elite soccer players (age 24.24 ± 5.75 years, height 178.21 ± 5.44 cm, weight 74.12 ± 5.21 kg) participated in this study. This observational study compared the same players' aerobic capacity pre-, and 60-days post COVID-19 recovery. The statistical analysis demonstrated that the infected players had significantly lower VO2max values [t(20) = 5.17, p < 0.01, d = 0.613 (medium effect)], and significantly lower VO2 values at respiratory compensation point (RC) [t(20) = 2.97, p < 0.05, d = 0.39 (small effect)] after recovery. Furthermore, results indicated a significantly lower running time (RT) on the treadmill [t(20) = 4.84, p < 0.01, d = 0.46 (small effect)] when compared to the results that were obtained before they got infected. In addition, velocity at VO2max (VVO2max) was significantly lower [t(20) = 2.34, p < 0.05, d = 0.41 (small effect)] and the heart rate values at ventilatory threshold (VT) [t(20) = -2.79, p < 0.01, d = 0.55 (medium effect)] and RC [t(20) = -3.72, p < 0.01, d = 0.52 (medium effect)] were significantly higher post-recovery. The aforementioned findings indicate that post COVID-19 soccer players may not reach full recovery at two months. Therefore, our results highlight that further adaptations and improvements are needed with regard to aerobic capacity before soccer players return to



#17 Incidence, burden, and pattern of injuries in Spanish male youth soccer players: A prospective cohort study

Reference: Phys Ther Sport. 2022 Jun 30;56:48-59. doi: 10.1016/j.ptsp.2022.06.005. Online ahead of print.

Authors: Francisco Javier Robles-Palazón, Iñaki Ruiz-Pérez, Alba Aparicio-Sarmiento, Antonio Cejudo, Francisco Ayala, Pilar Sainz de Baranda

Download link:

Summary: The objective was to explore the incidence, burden, and pattern of injuries in Spanish male youth soccer players during a 9-month competitive season (from September to May-June). 314 young (10-19 years) soccer players participated in the study. Incidence, burden, location, type, severity, mechanism, and circumstance of injuries, as well as potential differences by tactical position, month of the year, age group, and maturity status were used as variables. A total of 146 time-loss injuries were sustained by 101 different players. This resulted in an overall injury incidence of 3.1 injuries per 1000 h, a training injury incidence of 1.8 injuries per 1000 h, and a match injury incidence of 11.2 injuries per 1000 h. The probability of injury over the season was 34%. Most of the injuries affected the lower extremity and were classified as muscle/tendon injuries, with hamstring muscle injuries representing the most burdensome diagnosis. The incidence of injuries increased with age and maturation, but a heightened risk of overuse injuries during periods around peak height velocity was also identified. These findings suggest a need for implementing specific injury prevention measures. Due to the high burden shown, these measures should mainly focus on reducing the number and severity of hamstring muscle injuries.



#18 Isokinetic Muscle Strength in Elite Soccer Players 3 and 6 months After Anterior Cruciate Ligament Reconstruction

Reference: J Strength Cond Res. 2022 Jul 8. doi: 10.1519/JSC.0000000000004331. Online ahead of print.

Authors: Andreja Milutinović, Vladimir Jakovljević, Milinko Dabović, Oliver Faude, Dragan Radovanović, Emilija Stojanović

Summary: The aim of this study was to evaluate interlimb symmetry in quadriceps and hamstring peak torque of elite soccer players at 3 months (stage 1) and 6 months (stage 2) after anterior cruciate ligament (ACL) reconstruction. Eight male professional soccer players competing at the highest level across different European countries, who had undergone ACL reconstruction, participated in this study. All patients underwent a supervised physiotherapy program after surgery. Data analyses included the use of separate two-way repeated-measures analyses of variance and effect sizes. Although knee extensor and flexor strength of the non-injured limb was found to be relatively unaltered (g = -0.10 to 0.00) between stage 1 and stage 2, comparisons across time points revealed moderate improvements in quadriceps peak torque (p = 0.01, g = 0.52), hamstring peak torque (p = 0.07, g = 0.51), and hamstring:quadriceps (H/Q) ratio (p = 0.03, g = -0.68) of the injured leg, as well as small-large improvements in the quadriceps (p = 0.004, g = 1.24) and hamstring limb symmetry index (LSI) (p = 0.056, g = 0.41). A time-dependent moderate-large asymmetry observed at stage 1 between the injured and noninjured leg in quadriceps peak torque (p < 0.001, g = -1.83), hamstring peak torque (p = 0.157, g = -0.67), and the H:Q ratio (p = 0.06, g = 1.01), as well as between the hamstring and quadriceps LSI (p = 0.03, g = -0.74) was eliminated at stage 2 (g = -0.31 to 0.42). Our findings indicate the importance of supervised and comprehensive therapy, as well as strength screening to assist in recovery aimed at optimizing identified strength deficits following ACL reconstruction.


The Training Manager -