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 specific reconditioning training program implemented 12 months after ACL surgery improves lower-limb jump variables in amateur soccer players

Reference: Front Physiol. 2025 Aug 5:16:1630156. doi: 10.3389/fphys.2025.1630156. eCollection 2025.
Authors: Sergio Jiménez-Rubio, Tomás García-Calvo, Luis Manuel Martínez-Aranda, Javier Raya-González
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12392115/pdf/fphys-16-1630156.pdf
Summary: Introduction Soccer players are frequently exposed to high physical demands, which increase their risk of injury, especially anterior cruciate ligament (ACL) ruptures. Despite completing standard rehabilitation protocols, many athletes show persistent functional deficits one year after surgery. This study aimed to assess the impact of a 12-week reconditioning training program, focusing on adjacent joint mobility, neuromuscular control, plyometrics, stability-landing exercises, and strength production, of amateur soccer players 12 months after undergoing anterior cruciate ligament (ACL) surgery. Twenty-five Spanish male amateur soccer players (age = 21.2 ± 2.4 years) participated voluntarily. All participants followed similar return-to-play guidelines and were randomly assigned to either the control group (CG, n = 13) or the experimental group (EG, n = 12). Soccer players in the EG underwent the 12-week training program (ACLrPRO), and both groups completed jump battery tests before and after the intervention period. The results showed improvements in all analyzed variables for the EG, except for the time to stabilization during the single-leg land and hold test for their non-injured leg, where the CG showed better results. Moreover, players in the CG exhibited a decline in performance related to their non-injured leg across all performed tests. The EG also demonstrated lower absence days during the experimental period compared to the CG. These findings underscore the significance of implementing a targeted neuromuscular training program for soccer players recovering from an ACL rupture, especially in enhancing performance and reducing absence days after their return to competition.

2 Female high school soccer injuries presenting to US emergency departments: A 10-year analysis of national injury data

Reference: J Orthop. 2025 Aug 12:69:324-328. doi: 10.1016/j.jor.2025.08.017. eCollection 2025 Nov.
Authors: Jennifer Yu, Avanish Yendluri, Julian V Javier, Sohan S Shah, Jeffrey Yu, Dennis M Bienstock, et al.
Summary: Female athletes are underrepresented in sports injury research, especially regarding soccer-related injury patterns in adolescent females. This study analyzes injury trends among high school-aged female soccer players to address injury risks in this population. We hypothesize that soccer-related injuries in high school-aged females most commonly involve the head or lower extremities, with incidence decreasing over time due to improved prevention measures. The National Electronic Injury Surveillance System (NEISS) was queried for soccer-related injuries in females aged 14-18 from 2014 to 2023. Demographics, injury sites, and diagnoses were analyzed. National estimates (NEs) were calculated using NEISS statistical weights. Linear regression evaluated trends over time. From 2014 to 2023, an estimated 227,217 soccer-related injuries occurred in high school-aged females (7248 NEISS cases). Strains/sprains were the most common diagnosis (NE = 96,619, 33.2 %), followed by head injuries and concussions (NE = 57,311, 19.7 %). The head was the most frequently injured body part (21.1 %), followed by the ankle (20.6 %) and knee (15.7 %). Injuries significantly declined over time (p < 0.05). Notably, injuries decreased by 53.4 % from 2019 to 2020 but rose by 57.7 % from 2020 to 2021. There was a significant decline in female high school soccer injuries from 2014 to 2023, with head and lower extremity injuries being most common. The high frequency of head injuries emphasizes the importance of concussion baseline testing and treatment protocols. The decline in injuries, particularly head injuries, may reflect the effectiveness of prevention strategies implemented during the study period. This study highlights the need for targeted prevention strategies, including baseline concussion testing, protective gear, and improved training practices. The decline in injury rates suggests the positive impact of safety measures while identifying areas for further improvement to ensure player safety.

3 Exploration of the path of digital technology empowering the sustainable development of alumni football-a study based on ordinal logistic regression analysis

Reference: Front Sports Act Living. 2025 Aug 20:7:1613339. doi: 10.3389/fspor.2025.1613339. eCollection 2025.
Authors: Jiao Wang
Download link: https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2025.1613339/full
Summary: In the digital era, professional sports have rapidly embraced technologies such as big data, AI, and the Internet of Things to optimize performance, strategy, and fan engagement. However, the digital transformation of grassroots and amateur level sports remains significantly underdeveloped, posing a major obstacle to the inclusive and sustainable growth of national sports ecosystems. Alumni football, participated in by a vast and growing population of college graduates in China, emerges as a strategic gateway to bridging this digital divide. This study explores how digital technologies can empower the sustainable development of alumni football from the perspectives of data acquisition, processing, and application, with a focus on seven practical digital implementation scenarios. Using a questionnaire survey of 100 university football alumni and ordinal logistic regression analysis, ten digital factors were examined for their influence on alumni football development. The results show that factors such as digital business models and digital team culture significantly contribute to sustainable development, whereas elements like virtual coaching and match data management have relatively limited impact. This study not only addresses an urgent gap in digital grassroots sports integration but also provides replicable insights for policy makers, educators, and industry stakeholders aiming to promote large scale participation, cultural cohesion, and digital inclusion across broader segments of the sports domain.

4 No major changes in injury incidence in European club football during the 2022/23 FIFA World Cup season: a subanalysis of the UEFA Elite Club Injury Study

Reference: BMJ Open Sport Exerc Med. 2025 Sep 1;11(3):e002772. doi: 10.1136/bmjsem-2025-002772. eCollection 2025.
Authors: Håkan Bengtsson, Martin Hägglund, Jan Ekstrand, Anna Hallén, Markus Waldén
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12406901/pdf/bmjsem-11-3.pdf
Summary: The aim was to compare injury incidences between the 2022/23 season and the preceding five seasons, and between World Cup players and non-World Cup players during the 2022/23 season. During the 2022/23 season, 29 teams participated in the Union of European Football Associations Elite Club Injury Study and reported football exposures and injuries prospectively. Injury incidence was compared with that of the five preceding seasons for the full season and for periods before and after the Fédération Internationale de Football Association World Cup 2022. In addition, World Cup players were compared with non-World Cup players. Incidences were compared using rate ratio (RR) with 95% CI. Injury incidences during the 2022/23 season were similar to previous seasons except for training incidence which, due to a significantly lower incidence in the 2017/18 season compared with all other seasons, was higher during the full season (RR 1.10, 95% CI 1.00 to 1.21) and in the period before the World Cup (RR 1.17, 95% CI 1.02 to 1.35). World Cup players had similar injury incidences before and after the tournament (training incidence; RR 0.95, 95% CI 0.65 to 1.38, match incidence; RR 1.15, 95% CI 0.87 to 1.52) but a significantly lower match incidence than non-World Cup players before the tournament (RR 0.84, 95% CI 0.71 to 1.00). No major changes in injury incidences were observed during the 2022/23 season compared with previous seasons. World Cup players experienced similar injury incidences before and after the tournament, and had a lower match injury incidence before the tournament compared with non-World Cup players.

5 No differences in executive functions between female and male young talented football players

Reference: Front Psychol. 2025 Aug 19:16:1635329. doi: 10.3389/fpsyg.2025.1635329. eCollection 2025.
Authors: Jennifer Lehmann, Stefanie Pietsch
Download link: https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2025.1635329/full
Summary: Research regarding the relationship between cognitive performance and sport performance in young talented football players has mainly been investigated in male athletes. Only few studies have addressed these aspects in female athletes. Thus, this quasi-experimental cross-sectional study aims to contribute to research addressing possible sex differences in the relationship of cognitive aspects in young talented football players during a selection assessment for a representative team and possible adjustments in this process or training processes in consideration of potential sex differences. Therefore, the participants were assessed using a general questionnaire, the Number Connection Test (ZVT), and a resilience questionnaire (1st session), as well as the 2-back test, the Flanker test, and the Switching task (computer-based, 2nd session). In total 59 male and 47 female athletes aged between 12 and 13 years were included. The results of this study did not show any differences in executive function performance between female and male talented football players. Additionally, when examining potential differences between players selected for a representative team and those, who were not, no such differences were detected. Neither in general, nor sex-specific. The results suggest that further research is necessary to clarify whether there are sex differences among talented young football players and whether these differences play a role in the selection for a representative team.

6 Hip internal rotation restriction and heel raise mechanics as risk factors for Jones fractures in youth football players

Reference: Asia Pac J Sports Med Arthrosc Rehabil Technol. 2025 Aug 21:42:15-20.
 doi: 10.1016/j.asmart.2025.08.007. eCollection 2025 Oct.
Authors: Tomoki Koyama, Yoshitomo Saita, Tomohiko Tateishi, Tomokazu Tanita, Hiroki Ukita, Toshiro Shima, Nobuyuki Itaya, Haruki Yaguchi, Nanako Yamamoto, Yu Mori, Toshimi Aizawa, Masashi Nagao
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12396469/pdf/main.pdf
Summary: Jones fractures, stress fractures at the proximal metaphyseal-diaphyseal junction of the fifth metatarsal, are common in sports that involve repetitive jumping and turning, particularly football (i.e., soccer). The incidence among Japanese football players is higher than in Europe, with a high refracture rate, particularly in conservatively managed cases. Although surgical treatment is preferred for athletes, limited data exist on risk factors in youth players. This study aimed to investigate the prevalence and risk factors for Jones fractures among high-level Japanese high school football players through medical examinations. Medical examinations were conducted during the 2024 tournament involving 20 top-level high school teams (567 players). Ultrasound and X-ray imaging identified fractures, and players underwent various physical tests, including hip internal rotation (HIR) and weight-bearing position during a single heel raise (SHR). A questionnaire collected demographic data and fracture histories. Statistical analyses, including the Wilcoxon signed-rank test and Mann-Whitney U test, were conducted to determine associations with fracture risk. Of 232 male players (40.9 % of all), 18 (7.8 %) tested positive on ultrasound, seven (3.0 %) had confirmed fractures on radiography, and 11 reported a history of Jones fractures. Players with restricted HIR <30° and lateral weight-bearing during SHR showed a significantly higher fracture risk (Crude Odds Ratio: 3.74, p = 0.01). Additional lateral weight bearing during SHR increased the risk (Crude Odds Ratio, 4.02; p = 0.007). Restricted HIR and lateral weight-bearing during SHR were identified as risk factors for Jones fractures in youth football players. Recognizing these factors may enable targeted preventive measures to reduce injury risk in high-level athletes.

7 Sex differences in association football: a scoping review

Reference: PeerJ. 2025 Aug 27:13:e19976. doi: 10.7717/peerj.19976. eCollection 2025.
Authors: Wangyang Xu, Diyan Zhang, Xinbi Zhang
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12398286/pdf/peerj-13-19976.pdf
Summary: Despite some reviews examining sex differences in football within specific themes, a comprehensive, integrated overview of sex differences in football is lacking. This scoping review aimed to: (1) synthesize existing evidence regarding sex differences in elite football players; (2) identify research gaps to provide direction for future studies. The protocol adhered to the PRISMA Extension for Scoping Reviews guidelines. The searches were conducted on October 17, 2024, in Scopus, PubMed, ScienceDirect, and Web of Science (Core Collection). The risk of bias was assessed using the Revised Risk of Bias Assessment Tool for Nonrandomized Studies of Interventions (RoBANS 2). A narrative synthesis was performed to summarize the main findings. A total of 80 studies met the eligibility criteria and were included in the review, encompassing 4,896 players (2,226 female, 2,670 male) and 234 matches (99 female, 135 male). Seventy-two studies (90%) did not report female participants‘ menstrual cycles or contraceptive medication use. Only six studies exclusively used „sex“-related terminology, with not a single study using „gender“-related terminology alone. Seventy-four studies (93%) presented various degrees of mixed usage of the terms „sex“ and „gender“. All included studies were categorized into eight themes according to their research focus: Anthropometrics, Muscle and Joint Movements, Physiological Response, Physical Performance, Technical Performance, Match Performance, Psychological and Behavioral Performance, and Nutrition/Recovery/Sleep. Perhaps due to a combination of innate biological factors and acquired dietary habits, female players, who typically have a higher body fat percentage and lower lean body mass, exhibit performance gaps compared to male players in terms of speed, strength, and endurance. These differences further affect their technical skills and match performance. However, while these absolute differences exist, they often diminish or even disappear when data are standardized against certain anthropometric or physiological metrics. This underscores the importance of developing individualized analytical methods and evaluation criteria tailored to female players. Future studies should carefully define sex-specific inclusion/exclusion criteria and select appropriate sex and gender terminology to minimize bias and enhance study quality.

8 Benchmarking the Physical Performance Qualities in Women’s Football: A Systematic Review and Meta-analysis Across the Performance Scale

Reference: Sports Med. 2025 Sep 1. doi: 10.1007/s40279-025-02251-0. Online ahead of print.
Authors: Heidi R Compton, Ric Lovell, Dawn Scott, Jo Clubb, Tzlil Shushan
Download link: https://link.springer.com/content/pdf/10.1007/s40279-025-02251-0.pdf
Summary: There is a lack of data and its systematic organisation relating to the physical performance qualities of women’s football players across the performance scale (i.e. level of competition categorised into unique tiers). The aim was to 1) establish meta-analytic estimates for select assessment protocols across seven physical qualities (cardiorespiratory fitness, sprint time, acceleration time, change of direction, lower limb power, lower limb strength, and maximal velocity), and 2) to investigate the moderating effect of participant tier; collectively providing normative benchmarking data. A systematic literature search of four databases (Pubmed, SportDiscuss, Scopus, and Web of Science) for studies published between 2003 and 2023 was conducted, with a secondary search for studies published until August 2024. Studies were considered for inclusion if they were published in English, the population was female football players with a minimum mean age of 16 years and the studies reported descriptive data from selected testing protocols. All study designs were eligible, excluding acute interventions such as training or supplementation. Performance scale (i.e. participant tier) of the study participants was categorised into four distinct levels (Tier 2 to Tier 5) using a modified version of the Participant Classification Framework, with Tier 5 representing world-class athletes. Study risk of bias assessment was conducted using an adapted version of the Downs and Black tool. Means and standard deviations were analysed using mixed-effects, multilevel hierarchical models to obtain pooled estimates, 90% confidence intervals (CIs) and prediction intervals (PIs). Meta-regression of modifying effects for participant tier was conducted, and comparisons were expressed as standardised mean differences. The final dataset included 1855 estimates from 982 groups across 288 studies. The moderating effect of participant tier was assessed where adequate data permitted. Yo-Yo Intermittent Recovery Test Level 1 (YYIRL1) demonstrated moderate-to-large improvements when progressing from Tier 2 to Tiers 4 and 5 (combined; [b = 170 to 354 m]); similar improvements were observed for velocity attained during the 30-15 Intermittent Fitness Test when directly comparing Tier 2 to Tiers 4 and 5 (b = 2.5 km·h-1). Sprint time decreased when progressing between tiers, with a moderate-to-large reduction for both 20 m (b = – 0.17 to – 0.22 s) and 30 m (b = – 0.32 to – 0.47 s) time when comparing Tier 2 with Tier 3 and Tiers 4 and 5, respectively. Moderate-to-large improvements in jump height were observed for squat jump (SJ; restricted arm movement) between participant tiers (b = 3.6 to 6.2 cm) and similarly for countermovement jump (CMJ) when comparing Tier 3 with Tiers 4 and 5 for restricted (b = 3.3 cm) and unrestricted arm movement (b = 8.8 cm). Normative benchmarks that are useful for athlete profiling and development, talent identification, and training program design have been established from a very large sample of studies and athletes. These findings highlight the role of sprinting ability, lower limb power and intermittent aerobic capacity in differentiating athletes across the performance scale. Field-based tests, particularly those assessing intermittent fitness, demonstrated the greatest difference in performance between each of the participant tiers, suggesting that these pragmatic tests are effective at capturing the physical performance of women’s football players. A limitation of this study is the variability introduced by the heterogeneity across studies in testing protocols, sample sizes and competition levels, which may have influenced the results.

9 Physical and psychological demands of walking football in tournaments: Implications for older adults

Reference: J Sports Sci. 2025 Sep 1:1-13. doi: 10.1080/02640414.2025.2550055. Online ahead of print.
Authors: Maite Lejonagoitia-Garmendia, Susana M Gil, Xabier Monasterio, Izaro Esain, Iratxe Duñabeitia, Jone Torre-Sainz, Rakel Berriozabalgoitia, Iraia Bidaurrazaga-Letona 
Summary: This study investigated physical and psychological demands, performance, wellness perceptions, enjoyment and injury incidence among Over-50s and Over-60s walking football (WF) players during an international tournament. It involved 54 male players from the Basque, English, French and Italian squads. It collected data over two consecutive days, with each team playing one 40-minute match per day. Internal load was measured via heart rate (HR), lactate concentration and ratings of perceived exertion (RPE). External load was measured via minutes played, distance covered, accelerations, decelerations and speed. Game performance (passes, fouls and shots), wellness and injuries were recorded. Both age groups spent 85% of their playing time above 81% of their maximal HR, with elevated post-match lactate concentrations indicating significant exertion (p < 0.05), although RPE remained moderate. The Over-50s covered more distance and exhibited greater acceleration and deceleration rates than the Over-60s (p < 0.05), who showed a shift to slower movements on day two (p < 0.05). The Over-50s had higher pass success but committed more fouls (p < 0.05), while the Over-60s had more running-related fouls (p < 0.05). Both groups reported similar wellness and enjoyment levels, with minimal injuries. This study highlights the physical demands of WF tournaments and suggests that the benefits outweigh the risks for older adults.

10 Positional relative age effect in europe’s top ten football leagues

Reference: BMC Sports Sci Med Rehabil. 2025 Aug 30;17(1):258. doi: 10.1186/s13102-025-01312-1.
Authors: Mücahit Işık, Mehmet Yavuz, Osman Dişçeken, Halil İbrahim Ceylan, Tugay Öksüz, Kadir Demir
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12398170/pdf/13102_2025_Article_1312.pdf
Summary: A previous study confirmed the existence of the relative age effect (RAE) in the top ten leagues of the Union of European Football Associations (UEFA) during the 2016-2017 season, reporting that the effect was particularly pronounced among defenders and midfielders. The present study investigates whether this effect persists. Specifically, it aims to examine the RAE among professional male footballers in UEFA’s top ten leagues during the 2023-2024 season, and to explore how the effect varies by playing position and league. The study analysed the birthdates and playing positions of 5,238 professional footballers. Birthdates were categorised into four quartiles: Q1 (January 1 to March 31), Q2 (April 1 to June 30), Q3 (July 1 to September 30), and Q4 (October 1 to December 31), and were examined in detail by league and position. Players born in Q1 (30.3%) were overrepresented compared to those born in Q4 (20.5%) (χ² = 132.470, p < .05). This difference was statistically significant in most leagues, particularly in Serie A (χ² = 33.535, V = 0.14), Ligue 1 (χ² = 23.741, V = 0.11), LaLiga (χ² = 22.491, V = 0.12), and Bundesliga (χ² = 21.681, V = 0.12), but not in Premier League (χ² = 1.665, p = .645). In terms of playing position, the RAE was present across all groups (p < .05), with the most pronounced effect observed among goalkeepers (χ² = 40.006, V = 0.15). Positional RAE patterns varied across leagues: significant differences were found for goalkeepers in Serie A, Süper Lig, and LaLiga; for defenders in LaLiga and Jupiler Pro League; for midfielders in Serie A, Ligue 1, Süper Lig, and Eredivisie; and for forwards in Ligue 1, Bundesliga, and Scottish Premiership (p < .05). The findings indicate that the RAE persists in professional football within UEFA’s top leagues. The effect is evident across all playing positions and varies by league context.

11 How do college coaches in the United States identify youth female and male soccer players?

Reference: PLoS One. 2025 Sep 12;20(9):e0331134. doi: 10.1371/journal.pone.0331134. eCollection 2025.
Authors: Matthew Andrew, Sam Barraclough, Andrew O Triggs, James H Dugdale, Adam Kelly, Matthew J Reeves
Download link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0331134#:~:text=Results%20showed%20coaches%20across%20female,the%20most%20preferred%20scouting%20method.
Summary: Talent identification (TI) in soccer is a complex and multifactorial process within the context of collegiate sport in the United States, where coaches must assess performance-ready athletes often under strict regulatory and resource constraints. Despite the critical role college coaches play in bridging youth to professional soccer, little is known about their evaluative priorities during recruitment. This study examined how soccer coaches from female and male NCAA Division I and II programs perceived the importance of various player attributes and scouting methods in the TI process. A total of 178 college soccer coaches completed a survey assessing perceptions across seven attribute categories (technical, physical, psychological, game intelligence, social, other, and coach-specific) and common scouting methods. Bootstrapped trimmed means, effect sizes, and inter-rater agreement (rwg) were used to analyse the coaches‘ ratings of importance across attributes and to assess for differences in coach perceptions within the female and male programs. Results showed coaches across female and male programs rated technical proficiency, coachability, decision-making, and work rate as critically important. College-specific soccer knowledge was the most highly valued coach attribute, while live match observation was the most preferred scouting method. Sex-based differences were generally minimal, although emerged in perceptions of physical and social attributes, with coaches of female players placing greater emphasis on communication and agility. Results highlighted a shared prioritisation of technical and psychological qualities in college TI, with contextual differences influenced by sex and program structure. These insights support the development of more aligned and evidence-informed TI strategies in collegiate soccer environments.

12 Exploring Eccentric Hamstring Strength: Peak Force, Torque, and Impulse Metrics in Elite Academy Soccer Players

Reference: Res Q Exerc Sport. 2025 Sep 11:1-9. doi: 10.1080/02701367.2025.2544836. Online ahead of print.
Authors: Eduardo Tondelli, Luciano Tomaghelli, Franco Tedesco, Alejo Feroldi, Juan Herbella, Agustín Baldjian, Nicol Van Dyk
Summary: This study aimed to characterize eccentric strength metrics and the bilateral asymmetry index of the knee flexor muscles across different categories in elite academy soccer players. Also, explore correlations between the metrics with demographic characteristics. With a cross-sectional design, data were collected over two weeks during the mid-year break of the 2023 season. Eccentric muscle strength was assessed with the Nordic Hamstring Exercise (NHE) with the NordBord®. One hundred thirty-two male elite academy soccer players between 13 and 20 years old (16.3 ± 2.2 years; body mass (BM): 68.8 ± 6.5 kg; height: 174 ± 7 cm) competing in the Argentinian Football League participated. Metrics included were relative and absolute peak force (PF), peak torque (PT), and eccentric impulse (EI). Bilateral asymmetry index (BAI) was calculated for each metric. Eccentric PF, PT, and EI significantly increased with age. BAI decreased from the U17 category onward. Moderate correlations were observed between PF and PT with BM (r = 0.45, p < .001, 95% CI: 0.31-0.58; and r = 0.54, p < .001, 95% CI: 0.41-0.65, respectively), and PF with body mass index (BMI) (r = 0.37, p < .001, 95% CI: 0.22-0.51). EI had weaker correlations with BM (r = 0.12, p < .1665, 95% CI: -0.061-0.3). PF and PT peaked at the U17 and declined in older categories. To conclude, this study found higher eccentric hamstring strength values in elite youth soccer players than previously reported. PF showed moderate correlation with BMI, while EI had weak correlations with BM. Significant age-related variations in BAI were observed, particularly in younger players.

13 Effects of Small-Sided Games and High-Intensity Interval Training on The Rating of Perceived Exertion in Soccer Players Across Competitive Levels: Controlling for Percentage of Heart Rate Reserve

Reference: J Sports Sci Med. 2025 Sep 1;24(3):603-612. doi: 10.52082/jssm.2025.603. eCollection 2025 Sep.
Authors: Weiqiang Xu, Robert Trybulski, Le Luo, Grzegorz Trybek, Waldemar Moska, Yufei Liu, Filipe Manuel Clemente
Summary: This study investigated perceived exertion (RPE) differences among soccer players at two competitive levels – Tier 2 (trained) and Tier 3 (highly trained) – during small-sided games (SSGs) and high-intensity interval training (HIIT), while controlling for internal physiological load using percentage of heart rate reserve (%HRreserve). Seventy-seven male university players from the China University Football Association participated (Tier 2: n = 37; Tier 3: n = 40). Each player underwent a fitness assessment to determine HRmax and HRrest, followed by four randomized training sessions: 5v5 SSGs, 1v1 SSGs, long HIIT, and short HIIT. Heart rate was continuously monitored, and players reported RPE using the Borg CR10 scale immediately post-session. A linear mixed-effects model was used, with competitive level and training format as fixed effects, and %HRreserve included as a statistical covariate. The analysis revealed a significant interaction between training format and competitive level (F(3, 224.761) = 3.20, p = .024), indicating that the influence of training format on RPE varied by competitive level. A significant main effect of training format was also found (F(3, 234.484) = 11.24, p < .001). Specifically, Tier 3 players reported higher RPE during short HIIT than Tier 2 players (p = .002). Both groups reported lower RPE during 5v5 SSGs compared to 1v1 SSGs and HIIT formats (all p ≤ .003). These findings show that training format influences RPE in a format- and tier-specific manner, even when accounting for internal physiological load. For coaches and sports scientists, larger-sided SSGs may be useful to reduce perceived exertion while maintaining cardiovascular demand. Future research should include elite players and assess psychological and physiological mediators to better understand the complex drivers of perceived effort.

14 Effects of Different Training Load Parameters on Physical Performance Adaptation in Soccer Players: How Complex Intensities Influence The Magnitude of Adaptations

Reference: J Sports Sci Med. 2025 Sep 1;24(3):475-484. doi: 10.52082/jssm.2025.475. eCollection 2025 Sep.
Authors: ZhiFeng Xiong
Summary: The aim of this study was to examine how physiological, locomotor, and mechanical load parameters contribute to variations in aerobic, anaerobic, and neuromuscular adaptations in male soccer players. A 12-week cohort study was conducted involving 41 male under-17 soccer players (16.4 ± 0.5 years old). All training sessions and matches were monitored using heart rate (HR) monitors, ratings of perceived exertion (RPE), and a global positioning system (GPS). The following variables were recorded daily: training impulse (TRIMP), session-RPE, total distance, high speed running (14.0 to 19.9 km/h, HSR), and very high speed running (>20 km/h, VHSR), and the number of accelerations and decelerations. Physical fitness was assessed twice – at baseline and after the 12-week intervention. The assessments included aerobic capacity via the Yo-Yo Intermittent Recovery Test (YYIRT), anaerobic capacity via the mean sprint time at Running-Based Anaerobic Sprint Test (RSAmean), muscle power using the Countermovement Jump (CMJ), and sprint performance measured in a 30-meter sprint. Simple linear regressions showed that both accumulated session-RPE (R2 = 0.446, β = 0.668, p < 0.001) and accumulated TRIMP (R2 = 0.417, β = 0.646, p < 0.001) were significant positive predictors of YYIRT delta, although explain less than half of variance. A multiple regression analysis revealed that accumulated VHSR significantly predicted RSAmean delta, indicating that higher VHSR values are associated with smaller and improved RSAmean (B = -0.003, p = 0.002), while HSR was not a significant predictor (p = 0.291). These findings suggest that internal load measures (session-RPE, TRIMP) are more strongly associated with aerobic adaptations, while specific external load metrics (e.g., VHSR) better explain RSA changes, highlighting the importance of modifying load monitoring strategies to the specific physiological adaptations targeted. Incorporating individualized load management based on these measures may help maximize performance improvements in practical contexts.

15 Impact of The Menstrual Cycle on Physical Recovery after Small-Sided Games: A Crossover Study in Women’s Soccer Players

Reference: J Sports Sci Med. 2025 Sep 1;24(3):532-542. doi: 10.52082/jssm.2025.532. eCollection 2025 Sep.
Authors: Ana Filipa Silva, Robert Trybulski, Grzegorz Trybek, Waldemar Moska, Felipe J Aidar, Francisco Tomás González-Fernández
Summary: The aim of this study was twofold: (i) to compare potential variations in reactive strength index (RSI), interleukin-6 (IL-6), and delayed onset muscle soreness (DOMS) between the early follicular and mid-luteal phases in response to small-sided games (SSGs); and (ii) to analyze potential interactions in the magnitude of responses to different SSG formats, specifically 1v1 and 5v5. A crossover study design was employed, involving 20 amateur female soccer players (age: 21.4 ± 1.8 years) who were randomly assigned to two groups. With a 15-day interval between sessions, participants underwent repeated assessments following 1v1 and 5v5 formats across two menstrual cycle phases (based on calendar estimates). Participants completed 1v1 and 5v5 sessions and were evaluated at four time points: at rest, immediately post-session, 24 hours post, and 48 hours post. A three-way repeated measures ANOVA was used to assess the effects of play format (1v1, 5v5), hormonal phase (early follicular, mid-luteal), and time (rest, post-exercise, 24h, 48h). RSI was assessed using a drop jump test, IL-6 was measured via salivary analysis, and DOMS was rated using a Likert scale. To control for potential confounders like nutrition, sleep, and training load, participants maintained their regular diet and training during the study, though individual variation in these factors could still affect the results. Significant interactions were found between menstrual cycle phase, format, and time for RSI (p = 0.040; ηp2 = 0.154) and IL-6 (p < 0.001; ηp2 = 0.773), but not DOMS (p = 0.121; ηp2 = 0.283). RSI was significantly lower and IL-6 significantly higher in the mid-luteal phase, especially in 1v1 sessions (RSI: p < 0.001; IL-6: p < 0.001). These findings suggest that neuromuscular fatigue and inflammatory responses to SSGs are modulated by menstrual cycle phase, with potential implications for optimizing training and recovery strategies in female athletes.

16 Comparing Individualized vs. Non-Individualized Locomotor Profiling on High-Intensity Interval Training Adaptations in Soccer Players: A Randomized Parallel Study

Reference: J Sports Sci Med. 2025 Sep 1;24(3):503-512. doi: 10.52082/jssm.2025.503. eCollection 2025 Sep.
Authors: DongMing Zhu, DongMei Song, ZhiDa Huang
Summary: This study aimed to compare the effects of individualized versus non-individualized HIIT programming, based on players‘ locomotor profiles, on the magnitude of adaptations in aerobic, anaerobic, and neuromuscular capacities. A randomized, controlled, parallel-group design was conducted with 46 male youth soccer players (age: 16.5 ± 0.5 years), who were allocated into four groups: individualized HIIT (HIITind), long-interval HIIT only (HIITlong), repeated sprint training only (RST), and a control group that maintained regular training without any HIIT intervention. In the HIITind group, players were assigned to either HIITlong or RST based on their locomotor profile – endurance or speed-oriented – determined by the difference between maximal sprint speed (MSS) and maximal aerobic speed (MAS), respectively. In contrast, players in the HIITlong and RST groups followed the same protocol regardless of their profile. The training intervention lasted six weeks, with sessions conducted twice per week. Players were assessed at baseline and post-intervention for countermovement jump (CMJ), MSS over 30 meters (km/h), repeated sprint ability (RSA), and MAS, using the 5-minute running test. Significant improvements were found in all training groups compared to the control. RST showed greater improvements in CMJ (p < 0.001), MSS (p < 0.001), anaerobic speed reserve (ASR) (p < 0.001), and RSAmean (p < 0.001) compared to HIITind and HIITlong. No significant differences were observed between HIITind and HIITlong. Locomotor profiles influenced MSS (p < 0.001) and ASR (p < 0.001). These findings suggest that while both individualized and non-individualized HIIT protocols improve physical capacities, RST offers superior benefits for anaerobic and neuromuscular adaptations, whereas both HIITind and long are more effective than RST for enhancing aerobic capacity, with no significant differences observed between them.

17 Using Game-Based Compensatory Strategies in Non-Starter Soccer Players: Analyzing The Impact on Physical Fitness Development

Reference: J Sports Sci Med. 2025 Sep 1;24(3):495-502. doi: 10.52082/jssm.2025.495. eCollection 2025 Sep.
Authors: TongZheng Liu, Mingbang Li, XiaoYan Pu
Summary: The purpose of this study was to compare the effects of small-sided game-based compensatory strategies (CS) versus non-compensatory (NCS) strategies on the aerobic and repeated sprint ability development of non-starter soccer players. A controlled crossover experimental design was used, consisting of two 4-week phases separated by a 2-week washout period. Nineteen male non-starter soccer players (age: 18.1 ± 0.7 years) participated in the study. Each player experienced both an NCS and a specific CS, the latter involving six 3-minute bouts of 2v2 small-sided games performed the day after the match. CS indicates that additional training was introduced to compensate for the lack of playing time. This intervention was applied to players who either did not participate in the match or played less than 15 minutes. Physical fitness was assessed using the Yo-Yo Intermittent Recovery Test Level 1 (YYIRT) and the Running-Based Anaerobic Sprint Test (RSAmean). Significant interactions were found for YYIRT (p < 0.001, ηp2 = 0.587, large effects) and RSAmean (p < 0.001, ηp2 = 0.739, large effects). CS presented better results than NCS in YYIRT at both mid (mean difference: 84.4m, p = 0.040) and post-assessment (mean difference: 64.7m, p = 0.042). RSAmean was smaller under CS at mid (mean difference: -0.078 s, p = 0.012) and post-assessment (mean difference: -0.058s, p = 0.045). In conclusion, the results suggest that the CS condition leads to better YYIRT performance and reduced RSAmean compared to NCS. Practically, incorporating CS into training protocols for players who do not regularly participate in matches – such as unselected players or non-starters with limited playing time – may help maintain physical capacities, particularly endurance and repeated sprint ability, as these players are often exposed to lower physical demands during matches.

18 The Effects of Small Vs. Large-Sided Games on Physical Fitness Adaptations: A Randomized Controlled Design in Female Soccer Players

Reference: J Sports Sci Med. 2025 Sep 1;24(3):513-521. doi: 10.52082/jssm.2025.513. eCollection 2025 Sep.
Authors: Di Yang, Yun Feng, XuBin Guo, Pei Hu
Summary: Research comparing the effects of different small-sided soccer game (SSG) training formats on physical adaptations remains scarce. This study aimed to compare small-format SSGs (SSGSF: 1v1 to 3v3) with large-format SSGs (SSGLF: 6v6 to 8v8) on vertical jump, change-of-direction (COD), linear speed and aerobic capacity adaptations in youth female soccer players over a six-week training period. Using a simple randomized, parallel, controlled design, players were assigned to one of two experimental groups (SSGSF or SSGLF) or a control group. Forty-five female youth players (15.7 ± 0.5 years old) competing at a developmental level participated in the study. All participants had a minimum of two years of playing experience and adhered to at least 90% of the intervention protocol. The experimental groups received two additional SSG sessions per week, while the control group maintained their regular training routines. Baseline and post-intervention assessments included countermovement jump height (CMJ), change of direction deficit in the 5-0-5 test (COD deficit), 30-meter linear speed, and final velocity in the 30-15 intermittent fitness test (VIFT). The SSGSF group exhibited a significantly smaller CODdeficit compared to the control group (p = 0.026; d = 1.032, moderate) after the intervention. The SSGLF group exhibited a significantly smaller 30-m sprint time compared to the control group (p = 0.044; d = 0.303, small). Both the SSGSF (p = 0.039; d = 0.880, moderate) and SSGLF (p = 0.026; d = 1.043, moderate) groups exhibited a significantly greater VIFT compared to the control group. In conclusion, the findings suggest that SSGSF may be more beneficial for improving COD ability, while SSGLF could potentially be more effective for enhancing linear sprint performance. Both formats appear to have a positive impact on aerobic performance, though the extent of their effects might be similar. Coaches might consider these differences when selecting SSG formats, as each format could contribute differently to physical performance adaptations.

19 Can Maturation Level Influence Long-Term Physiological and Physical Adaptations in Youth Female Soccer Players Exposed to Combined Sided Games and HIIT? A Comparison Across Maturation Statuses

Reference: J Sports Sci Med. 2025 Sep 1;24(3):634-644. doi: 10.52082/jssm.2025.634. eCollection 2025 Sep.
Authors: Ying Zhou, Jing Liu, Liuxi Yang, Bosong Zheng
Summary: The aim of this study was to assess the effects of a 6-week high-intensity interval training combined with small-sided games (HIIT&SSG) program on maximal strength, sprint performance, and aerobic capacity in female athletes and to examine how these effects vary across different stages of maturity (pre-, mid-, and post-peak height velocity [PHV]). Specifically, we sought to determine whether the improvements in performance outcomes were consistent across maturity groups or if the training effects differed based on the athletes‘ maturity status. Fifty-four female soccer players (aged 9-16 years) were categorized into pre-PHV, mid-PHV, and post-PHV maturity groups. Participants were randomly assigned to either an HIIT&SSG group (n = 27) or a control group (n = 27). The HIIT&SSG group performed two additional training sessions per week, focusing on 2v2 small-sided games and individualized high-intensity runs at 85% of their final velocity during the 30-15 Intermittent Fitness Test (VIFT). Control continued their regular training routines. Pre- and post-intervention assessments included isometric mid-thigh pull (IMTP) for maximal strength, 30-meter sprint time, and VIFT for aerobic capacity. Pre- and post-intervention assessments included isometric mid-thigh pull (IMTP) for maximal strength, 30-meter sprint time, and VIFT for aerobic capacity. The HIIT&SSG group demonstrated large effect sizes for IMTP (ηp2 = 0.996), 30-m sprint time (ηp2 = 0.991), and VIFT (ηp2 = 0.878), with substantial improvements in strength and aerobic capacity in mid- and post-PHV athletes. For IMTP, significant group differences were observed in mid-PHV (p = 0.021) and post-PHV athletes (p < 0.001). Post-PHV athletes also showed significantly faster 30-meter sprint times post-intervention (p < 0.001). VIFT improvements were significant across all maturity stages (Pre-PHV: p = 0.045; Mid-PHV: p < 0.001; Post-PHV: p < 0.001). Effect sizes for group differences ranged from moderate to large (ηp2 = 0.540 to ηp2 = 0.928). HIIT&SSG program is effective in enhancing maximal strength, sprint performance, and aerobic capacity, with particularly benefits for mid- and post-PHV athletes. However, the improvements in sprint performance were primarily observed in post-PHV athletes, which may limit the generalizability of these effects to all maturity stages.

20 Beyond Playing Positions: Categorizing Soccer Players Based on Match-Specific Running Performance Using Machine Learning

Reference: J Sports Sci Med. 2025 Sep 1;24(3):565-577. doi: 10.52082/jssm.2025.565. eCollection 2025 Sep.
Authors: Michel de Haan, Stephan van der Zwaard, Jurrit Sanders, Peter J Beek, Richard T Jaspers
Summary: Soccer players are frequently categorized by playing positions, both in the scientific literature and in practice. However, the utility of this approach in evaluating physical match performance and optimizing physical training programs remains unclear. This study compares the effectiveness of categorizing soccer players by their playing position versus using unsupervised machine learning based on match-specific running performance. Match-specific running data were collected from 40 young elite male soccer players over two seasons. Thirty-one of these players completed a 20-meter sprint test and a maximal incremental treadmill test to measure maximal oxygen uptake. Players were categorized both by playing position and by subgroups derived through k-means clustering based on match-specific running performance. Differences in sprint capacity, endurance capacity, and match-specific running performance were compared between and within playing positions, as well as between and within clusters. The two categorization methods were further compared for variance within subgroups and standardized differences between subgroups for total distance (TD), low-intensity running (LIR), moderate-intensity running (MIR), high-intensity running (HIR), and sprint distance during matches. Match-specific running performance differed between playing positions, despite notable inter-individual differences in running intensities within playing positions. Clustering based on match-specific running performance revealed less variance within groups (TD: P = 0.049, LIR: P = 0.032, HIR: P = 0.033) and larger standardized differences between groups (LIR: P = 0.037, MIR: P = 0.041, HIR: P = 0.035, Sprint: P = 0.018) compared to grouping by playing position. Moreover, 20-meter sprint speed differed between the sprint and high intensity endurance clusters (25.22 vs 23.75 km/h, P = 0.012), but not between playing positions. Using unsupervised machine learning to categorize soccer players improves the identification of player groups with similar match-specific running performance, thereby supporting performance evaluation and contributing to the optimization of physical training.

21 Age-Related Differences in Jumping and Sprinting Performance and Force Production Capacities in Young Soccer Players

Reference: Eur J Sport Sci. 2025 Oct;25(10):e12301. doi: 10.1002/ejsc.12301.
Authors: Firas Zghal, Haitham Rebai, Serge S Colson, Pierre Samozino, Abderrahmane Rahmani, Nicolas Peyrot, Jean-Benoît Morin
Download link: https://onlinelibrary.wiley.com/doi/epdf/10.1002/ejsc.12301
Summary: The purpose of this study was to evaluate the evolution of jump and sprint force-production capacities with maturation in young soccer players. One hundred sixteen young elite male soccer players aged 11-17 years were assigned to six different groups according to their maturity status. The force-velocity (F-V) profiles in jumping and sprinting performances were compared among groups. The results show a significant, progressive, and linear improvement in the majority of F-V profile determinants of jumping and sprinting performances in parallel with maturation. When comparisons were carried out between consecutive groups, significant differences between PHV-1 and PHV groups in Hmax (p < 0.05), H60 (p < 0.05), VT-F0 (p < 0.05), and VT-Pmax (p < 0.05) were observed but disappeared when these variables were expressed relative to body mass. Regarding the F-V profile determinants of sprinting performance, we observed significantly shorter sprint times in PHV compared to PHV-1 and in PHV+2 in comparison with the PHV+1 group. These between-group differences were associated with significant greater HZT-F0 kg-1 (p < 0.05) and HZT-Pmax kg-1 (p < 0.001). However, significantly more negative value of HZT-Sfv kg-1 was observed in PHV-1 compared to PHV-2 (p < 0.05), in PHV+1 in comparison with PHV (p < 0.05) and in PHV+3 when compared to the PHV+2 group (p < 0.05). Thus, these findings revealed an alternation of accelerated periods of development in force and velocity qualities, expressing sprinting performance, with maturation during the physical development process of young soccer players. Trainers and coaches should be aware of the distinct mechanical characteristics related to each maturity stage and design specific programs accordingly.