FOOTBALLSCIENCE.NET

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 Within-player associations between GPS-derived external training load and heart rate-based internal training load in elite youth male soccer training

Reference: PLoS One. 2026 Sep 11;21(9):e0357176. doi: 10.1371/journal.pone.0357176. eCollection 2026.
Authors: Krisztián Havanecz, Tímea Téglás, Leonidas Petridis
Download link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0357176
Summary: This study examined within-player associations between GPS-derived external training load variables and heart rate-based internal training load during in-season training in elite youth soccer players. A secondary aim was to identify which intensity-based external load variables are independently associated with heart rate (HR) exertion per minute. Eleven under-17 male soccer players were monitored across a nine-week in-season period. 266 player-session observations were included. External training load was assessed using GPS units with integrated inertial sensors, including total distance covered, high-speed running distance, explosive efforts, player load, and their time-normalized derivatives. Internal training load was quantified using heart rate exertion derived from individualized HR zones. Within-player associations were examined using repeated-measures correlations. A linear mixed-effects model was used to examine predictors of heart rate exertion per minute. HR exertion showed nearly perfect within-player associations with total distance covered (r = 0.921, p < 0.001) and PlayerLoadTM (r = 0.924, p < 0.001), while large associations were observed for high-speed running distance (r = 0.662, p < 0.001) and explosive efforts (r = 0.621, p < 0.001). Intensity-based variables, including total distance covered per minute and explosive efforts per minute, were significant positive predictors of HR exertion·min – ¹. In elite under-17 youth soccer training, cumulative HR exertion primarily reflects accumulated external training volume, whereas HR exertion·min – ¹ is more closely related to locomotor and explosive action intensity. These findings highlight the need to interpret cumulative and intensity-based internal training load metrics separately in within-player training monitoring.

#2 Effects of different training modalities on lower-limb explosive power, acceleration, 20-m sprint performance, and change-of-direction ability in youth soccer players: a systematic review and network meta-analysis

Reference: BMC Sports Sci Med Rehabil. 2026 Sep 5;18(1):410. doi: 10.1186/s13102-026-02041-9.
Authors: Kaiqi Wang, Junhao He, Anjing Zhu, Xuecui Bi
Download link: https://link.springer.com/content/pdf/10.1186/s13102-026-02041-9.pdf
Summary: Youth soccer players repeatedly perform explosive actions, short accelerations, linear sprints, decelerations, and multidirectional movements. However, the comparative effects of different structured physical-conditioning programmes remain uncertain. Seven databases were searched from inception to 3 July 2026 using a final expanded search strategy encompassing plyometric, strength or resistance, sprint, acceleration, speed, change-of-direction, neuromuscular, multicomponent, and combined training. Randomised controlled trials involving healthy youth soccer players were eligible. Intervention arms were classified using operational, content-based node definitions. Construct-restricted primary networks and expanded sensitivity networks were analysed using frequentist random-effects network meta-analysis. Hedges‘ adjusted g was preferentially calculated from post-intervention or final-follow-up means, standard deviations, and sample sizes. Estimates were presented so that positive values indicated better performance. P-scores were treated as descriptive ranking summaries. Risk of bias was assessed using an adapted study-level application of the five-domain RoB 2 framework, and confidence in the evidence was assessed using CINeMA. A post hoc strict-age sensitivity analysis excluded two age-boundary studies. Eighty-nine studies were included in the expanded quantitative analysis, of which 74 contributed to at least one construct-restricted primary network. The primary lower-limb explosive-power, acceleration, 20-m sprint, and planned change-of-direction networks included 55, 20, 25, and 38 studies, respectively. Compared with usual soccer training, plyometric training combined with sprint and/or change-of-direction training showed favourable estimates for lower-limb explosive power (SMD 0.79, 95% CI 0.55 to 1.03), acceleration (1.19, 0.90 to 1.49), 20-m sprint performance (0.80, 0.33 to 1.28), and planned change-of-direction ability (1.46, 1.13 to 1.80). Corresponding I² values were 34.6%, 21.8%, 65.0%, and 41.0%. Between-design inconsistency was detected in the 20-m sprint (P = 0.0036) and change-of-direction (P = 0.0007) networks. CINeMA confidence for these four comparisons was low, low, very low, and low, respectively. Expanded sensitivity networks showed substantially greater heterogeneity. The highest-ranked intervention differed across outcome domains but remained consistent within each outcome across the three analysis sets. Excluding the two age-boundary studies did not materially alter the principal estimates. Plyometric training combined with sprint and/or planned change-of-direction training produced favourable comparative estimates across the four performance outcomes. However, evidence for several nodes and active-versus-active comparisons was sparse, heterogeneity in programmes and outcomes was present, inconsistency was detected in some networks, and confidence in the evidence was low or very low. These limitations do not support a conclusion that any training category is universally superior. The findings should be interpreted as provisional category-level signals rather than definitive training prescriptions.

#3 Elite Youth Soccer Players Outperform Subelite Peers in Fitness Measures When Matched for Age and Biological Maturity: A Cross-Sectional Study

Reference: Pediatr Exerc Sci. 2026 Sep 9:1-10. doi: 10.1123/pes.2026-0012. Online ahead of print.
Authors: Eduard Bezuglov, Anton Emanov, Georgiy Malyakin, Timur Vakhidov, Tamara Dolmatova, Elizaveta Kapralova, Vyacheslav Kolesnichenko, Mikhail Vinogradov, Matvey Irinin, Ryland Morgans
Summary: Eighty-nine players from a leading soccer academy and 93 players from subelite level sports schools aged 11-12 years with comparable chronological and skeletal age and training experience completed the following tests: 30-m sprint with 5-, 10-, and 20-m split times; standing horizontal jump; countermovement jump; change of direction running test; and speed dribbling test. The multivariate analysis of variance revealed a significant multivariate effect across all analyzed variables (Wilks λ = 0.4978, F8,179 = 22.57, P < .001), indicating that elite players outperformed subelite players across all performance tests. The training experience of elite young soccer players was marginally higher compared with subelite players (6.56 [1.27] y and 6.17 [1.02] y, respectively, P = .023, Cohen d = 0.34). Adjusted multivariate analysis of covariance confirmed that the group effect remained significant after controlling for chronological age, skeletal age, and sports experience (Wilks λ = 0.479, F8,170 = 23.10, P < .001). Linear regression demonstrated that training experience was a weak predictor, explaining only a small proportion of the variance in all measured performance metrics (R2 < .04). Elite young soccer players demonstrate superior speed, strength, and skill compared with subelite peers of similar biological maturity. These differences remained evident after adjustment for chronological age, skeletal age, and sports experience.

#4 Prioritizing next-day readiness decline in elite female soccer using readiness, workload, and wellness data: A temporally validated and calibrated monitoring framework

Reference: PLoS One. 2026 Sep 10;21(9):e0358036. doi: 10.1371/journal.pone.0358036. eCollection 2026.
Authors: Haojie Long,Longji Li,Lifeng Zhang
Download link: https://journals.plos.org/plosone/article?d=10.1371/journal.pone.0358036
Summary: Daily athlete monitoring is widely used in elite soccer, but its value depends on whether routine data can help identify athlete-days more likely to be followed by self-reported next-day readiness decline. This retrospective study evaluated a temporally validated and calibrated model for prioritizing staff-review attention in elite female soccer. Using SoccerMon data, we analyzed 14,428 eligible athlete-days from 50 players. The outcome was same-athlete next-calendar-day self-reported readiness decline ≥0.5 athlete-specific SD calculated from at least five observed readiness values strictly before the index date. Models were trained in 2020 and evaluated in a held-out 2021 test set. Adding workload and wellness to readiness improved discrimination (Model 4 vs Model 0: AUC 0.7645 vs 0.7043; PR-AUC 0.5135 vs 0.3808); paired athlete-level bootstrap ΔAUC was 0.0592 (95% CI 0.0288-0.0891). Platt recalibration reduced Brier score from 0.1924 to 0.1460 without changing ranking. Reviewing the top 20% (1,672 athlete-days) captured 881 events (46.1%) versus 36.4% for Model 0. These retrospective results support cautious staff-review prioritization rather than demonstrated improvement in athlete management or performance, and prospective implementation testing and independent external validation are required before real-world use.

#5 Creatine formulations and repeated sprint training: effects on physical and physiological adaptations in soccer players during the short-term preparation phase

Reference: J Int Soc Sports Nutr. 2026 Dec 31;23(sup1):2721147. doi: 10.1080/15502783.2026.2721147. Epub 2026 Sep 10.
Authors: Changyuan Duan, Zaitao Wang, Qianjin Wang
Download link: https://www.tandfonline.com/doi/epdf/10.1080/15502783.2026.2721147?needAccess=true
Summary: This research examined the impact of various creatine (Cr) supplementation formulations during a 4-week preparatory phase on the efficacy of repeated sprint training (RST) and on improvements in physical and physiological performance in male soccer athletes. A total of forty collegiate young soccer players volunteered for the study. They were randomly divided into four groups: creatine monohydrate (Cr-Mon, n = 10), creatine ethyl ester (Cr-Ee, n = 10), creatine hydrochloride (Cr-Hcl, n = 10), and placebo (PL, n = 10). All athletes engaged in a 4-week training intervention, three times a week (i.e. 12 sessions), and physical (countermovement vertical jump [CMVJ], 20-m sprint, and L-run) and physiological (Wingate anaerobic power and incremental exercise tests) performance were assessed both before and after the training period. All training groups improved physical and physiological performance following the 4-week intervention period (p < 0.05). Additionally, the groups receiving the Cr supplement exhibited significantly greater changes (p = 0.001) in physical performance, peak power output, and fatigue index compared to the PL group. However, no significant differences were found among the groups regarding mean power output and VO2max. Notably, the Ee and Hcl forms of Cr showed superior gains (p < 0.05) in physical performance and peak power compared to the Mon form after the 4-week intervention. The results underscore the importance of Cr ingestion in enhancing adaptations for short-term physical performance tasks, highlighting the effectiveness of the Ee and Hcl forms in further improving the CMVJ, 20-m sprint, L-run, and peak power among soccer players during the short-term preparation phase.

#6 High-Speed Running and Recovery Dynamics in Professional Soccer Match Play: A Comparison Between Starters and Substitutes

Reference: Int J Sports Physiol Perform. 2026 Sep 9:1-6. doi: 10.1123/ijspp.2026-0001. Online ahead of print.
Authors: Hugo Silva, João Ribeiro,Adriano Lima-Alves, Olivier Girard
Summary: This study compared the temporal structure of high-speed running (HSR) efforts and subsequent recovery profiles between starters and substitutes, and across playing positions, in professional soccer. Sixty-one male professional players (26.9 [5.2] y) from 2 teams were monitored across 24 official matches, resulting in 215 match observations (148 starters and 67 substitutes). Match running performance was monitored using 10-Hz global navigation satellite system units. Episode-level variables included HSR duration, recovery duration, HSR-recovery intervals, and intervals between consecutive HSR efforts. Linear mixed-effects models were used to compare playing roles, while recovery durations were categorized into <60 s, 60-120 s, and >120 s bands and analyzed using χ2 tests. Mean HSR duration did not differ between starters and substitutes (2.37 [1.64] vs 2.40 [1.75] s), nor were differences for HSR-recovery intervals (3.86 [3.59] vs 3.75 [3.55] s), HSR-HSR intervals (3.51 [3.48] vs 3.57 [3.16] s), or the HSR/recovery ratio (1.05 [1.53] vs 1.00 [1.66]) (all P > .05). However, starters displayed significantly shorter recovery durations than substitutes (13.34 [33.51] vs 16.72 [39.50] s; P = .017). Recovery-band distributions differed by playing role (P < .001), with starters completing a greater proportion (97% vs 93%) of short recoveries (<60 s), whereas substitutes exhibited relatively higher proportions of moderate (6%) and long (1%) recoveries. Playing position influenced temporal intervals and the HSR/recovery ratio, but not HSR or recovery duration. Despite longer recovery durations in substitutes, the overall temporal structure of HSR efforts was largely consistent between playing roles, with HSR and recovery periods predominantly occurring within short-time windows.

#7 Time-Frequency Analysis of Muscle Activation Patterns during the Instep Kick in Elite and Amateur Soccer Players

Reference: J Sports Sci Med. 2026 Sep 1;25(3):807-821. doi: 10.52082/jssm.2026.807. eCollection 2026 Sep.
Authors: Jiazhong Zhu, Diwei Chen, Dongxu Wang, Zhanyi Zhou, Yang Song, Xuanzhen Cen, Gusztáv Fekete, Monèm Jemni, Huw Wiltshire, Julien Steven Baker, Yaodong Gu, Dong Sun
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13552881/pdf/jssm-25-807.pdf
Summary: The instep kick is a frequently performed, high-load soccer skill that requires precise intermuscular coordination around ball contact. This study compared time-frequency activation patterns between elite and amateur male soccer players across two kicking phases and identified the key time windows and dominant muscle contributions. Surface electromyography was recorded from seven muscles of the kicking leg in 15 elite and 15 amateur players: rectus femoris, vastus medialis, vastus lateralis, biceps femoris, tibialis anterior, medial gastrocnemius, and lateral gastrocnemius. The instep kick was divided into Phase 1, from maximum hip extension to ball contact, and Phase 2, from post-contact follow-through to maximum hip flexion. Morlet wavelet analysis was used to generate time-frequency intensity maps. Global principal component analysis was then performed to extract PC1 to PC6, and between-group differences in PC score trajectories were assessed using SPM1D independent-samples t tests, with significance evaluated under a Bonferroni adjusted threshold for the 12 PC phase comparisons. In Phase 1, PC3 showed a significant between-group difference at 54-75% of the normalized time (peak t = 7.62, p < 0.001, Hedges‘ g = 2.96), with higher scores in the elite group. In Phase 2, PC1 differed significantly between groups at 60-70% of the normalized time (peak t = -9.88, p < 0.001, Hedges‘ g = -2.03), with higher scores in the amateur group. Elite players showed a more temporally focused pre-contact activation pattern centered on mid-frequency components of the biceps femoris, whereas amateur players showed greater reliance on higher-frequency components of the medial gastrocnemius during the post-contact follow-through. These findings suggest that skill-level differences are expressed as phase-specific redistribution of muscle and frequency-band activity within critical time windows, rather than as a simple global difference in activation magnitude.

#8 Game Density Modulates External Load During Small-Sided Games in Elite U17 Soccer Players

Reference: J Sports Sci Med. 2026 Sep 1;25(3):761-771. doi: 10.52082/jssm.2026.761. eCollection 2026 Sep.
Authors: Martin Bejbl, Jakub Kokstejn, Miroslav Grobar, Jindrich Vampola
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13552850/pdf/jssm-25-761.pdf
Summary: Evidence regarding the influence of relative area per player (ApP), and playing position, on locomotor- and mechanical- external load during small-sided games in elite youth soccer players remains limited. This study aimed to examine associations between continuous ApP and external load during training-based small-sided games in elite U17 soccer players, and to explore whether playing position modified these responses. Twenty-two elite U17 soccer players (16.6 ± 0.47 years) were monitored during small-sided games, using mostly formats such as 4v4, 5v5, and 8v8-using observations derived from individual player responses across SSG bouts under three-game-density conditions. External load variables included total distance (TD); high-speed running distance (HSR); sprint distance (SPRINT); number of sprints (NSPRINTS); accelerations (ACC); decelerations (DEC); high metabolic load distance (HMLD); and, maximal-speed exposure (%MSPEED). Linear mixed-effects models were used to examine associations between continuous ApP and each external load variable, while accounting for repeated observations, including players and session-level clustering. Larger ApP values were positively associated with HSR, SPRINT, NSPRINTS, HMLD, and %MSPEED. In contrast, no significant associations were observed between ApP and TD; ACC; or DEC. No significant main effects of playing position or ApP × position interactions were identified. Supplementary player-level effect-size analyses indicated recurring exploratory positional patterns, particularly for high-speed and sprint-related variables. These findings suggest that ApP is a practical programming variable for scaling high-intensity locomotor and metabolically-demanding external load in elite youth soccer, whereas additional task constraints may be required to specifically target acceleration- and deceleration-based demands.

#9 Effects of Blood Flow Restriction Training at Different Levels of Arterial Occlusion Pressure on Body Composition and Athletic Performance in Youth Soccer Players: A Randomized Controlled Trial

Reference: J Sports Sci Med. 2026 Sep 1;25(3):606-616. doi: 10.52082/jssm.2026.606. eCollection 2026 Sep.
Authors: Liang Qing, Tianyu Zhao, Linjie Wang, Li Zhu, Chao Dong, Jiancheng Liu, Xiaoming Hu, Sheng He, Tingting Zhou, Wenjing Shan, Xiang Gou, Rizhao Pang
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13552859/pdf/jssm-25-606.pdf
Summary: This study aimed to investigate the effects of low-load blood flow restriction training (BFRT) performed at different levels of arterial occlusion pressure (AOP) on body composition, maximal strength, and athletic performance in youth soccer players. Twenty-four male youth soccer players were randomly assigned to 40% AOP group, 60% AOP group, or control group. Participants in the BFRT groups performed lower-limb resistance training at 30% of one-repetition maximum (1RM) under the corresponding pressure conditions, whereas the control group trained without BFR. Training was conducted three times per week for six weeks. Body composition, back squat 1RM, countermovement jump (CMJ), T-test, and 30-m sprint performance were assessed before and after the intervention. Results showed that lower-limb muscle mass increased significantly in both the 40% AOP group (mean change = 0.55 kg, 95% CI: 0.13 to 0.97 kg, P = 0.010) and the 60% AOP group (mean change = 0.83 kg, 95% CI: 0.37 to 1.29 kg, P < 0.001), with the 60% AOP group showing significantly greater gains than the control group (between-group difference = 1.48 kg, 95% CI: 0.40 to 2.56 kg, P = 0.008). Back squat 1RM improved significantly in both the 40% AOP group (mean change = 6.50 kg, 95% CI: 3.90 to 9.10 kg, P < 0.001) and the 60% AOP group (mean change = 9.25 kg, 95% CI: 6.75 to 11.75 kg, P < 0.001), with the 60% AOP group demonstrating superior strength gains compared with the 40% AOP group (between-group difference = 2.94 kg, 95% CI: 0.20 to 5.68 kg, P = 0.048). CMJ height and T-test performance improved significantly in both the 40% AOP group (CMJ: mean change = 2.07 cm, 95% CI: 0.80 to 3.34 cm, P = 0.002; T-test: mean change = -0.23 s, 95% CI: -0.35 to -0.11 s, P = 0.001) and the 60% AOP group (CMJ: mean change = 2.65 cm, 95% CI: 1.00 to 4.30 cm, P = 0.003; T-test: mean change = -0.26 s, 95% CI: -0.38 to -0.14 s, P < 0.001), with no significant differences between the two BFRT groups (all P > 0.05). No significant changes were observed in 30-m sprint performance across groups (all P > 0.05). This study showed that six weeks of low-load (30% 1RM) blood flow restriction training performed at both 40% and 60% AOP was associated with improvements in lower-limb muscle mass, squat strength, and selected aspects of athletic performance in youth soccer players, compared with low-load training without BFR. While both pressure levels elicited comparable improvements in CMJ and agility performance, training at 60% AOP was associated with greater adaptations in lower-limb muscle mass and squat strength, with no additional benefits observed for 30-m sprint performance.

#10 Comparative Effects of Training Modalities on Countermovement Jump Performance in Soccer Players: A Systematic Review and Network Meta-Analysis

Reference: 2026 Sep 1;25(3):701-713. doi: 10.52082/jssm.2026.701. eCollection 2026 Sep.
Authors: Xusong Dong, Tao Li, Weihuan Xing, Zezhao Chen
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13552851/pdf/jssm-25-701.pdf
Summary: The aim of this study was to provide a comprehensive comparison of training modalities for countermovement jump (CMJ) performance in soccer players using a network meta-analysis (NMA). PubMed, Web of Science, Embase, EBSCO, and the Cochrane Library were searched up to November 2025. Randomized controlled trials (RCTs) involving healthy soccer players, evaluating structured training interventions against comparator training or control conditions, and reporting CMJ height outcomes were included. A random-effects NMA was performed to estimate mean differences (MDs) with 95% confidence intervals (CIs), and interventions were ranked using P-scores, integrating both direct and indirect evidence. Subgroup analyses were conducted according to age, sex, and competitive level. Twenty-nine RCTs (n = 450) were included. The network showed moderate heterogeneity and no evidence of significant inconsistency. Combined training (CBT) was ranked highest in effect estimates in CMJ performance compared with traditional soccer training (TST) (MD = 4.92, 95% CI: 3.02-6.83, P-score = 0.98), followed by flywheel resistance training (FT) and plyometric training (PT), whereas other interventions did not demonstrate significant improvements. Subgroup analyses indicated that CBT ranked highest in males, youth, and Tier 2 players; PT ranked highest in females and adults; and FT ranked highest in highly trained players. Given the limited sample sizes, limited statistical power, and the fragmented nature of some subgroup comparisons, these findings should be interpreted cautiously. The network showed moderate heterogeneity (I2 = 32.4%) and no evidence of significant inconsistency. The certainty of evidence was generally low to moderate according to the CINeMA assessment. Directness of evidence was generally high across comparisons, although several key contrasts (e.g., CBT vs FT and FT vs PT) relied partly on indirect evidence within the network. Although the highest-ranked interventions (CBT, FT, and PT) were supported primarily by direct comparisons with TST, several active-active contrasts relied partly on indirect estimates. The reliability of the intervention rankings depends on similarity in participant characteristics, intervention dose, outcome measurement, and control conditions.

#11 The Effectiveness of Passive Half-Time Interventions on Simulated Second-Half Performance in Elite Youth Soccer Players

Reference: 2026 Sep 1;25(3):617-626. doi: 10.52082/jssm.2026.617. eCollection 2026 Sep.
Authors: Brendon Skinner, Emily E Munn, Tim Roberts, Rachelle A Reed, Robin T Thorpe
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13552870/pdf/jssm-25-617.pdf
Summary: The half-time period in soccer provides a potentially important window to implement short-duration interventions aimed at maintaining second-half performance. However, passive rest has been associated with a decline in subsequent physical and technical performance. While re-warm-up strategies are well studied, little is known about the efficacy of technology-based, passive recovery modalities, device-supported interventions that require minimal active movement or physical exertion from the athlete, during half-time intervals. This study examined whether percussive therapy, electrical muscle stimulation, and pneumatic compression can mitigate second-half performance decline in male adolescent soccer players. Forty-three academy-level players (17.5 ± 0.6 years) completed a simulated soccer protocol including the Loughborough Soccer Pass Test (LSPT), repeated 20-meter sprints, and completed Total Quality of Recovery (TQR) assessments before and after half-time. Participants were randomized into one of four intervention groups during the 15-minute half-time interval: Passive Rest (CON), Percussive Therapy (Theragun Pro; TG), EMS (PowerDot; PD), and Pneumatic Compression (RecoveryAir; COMP). Linear mixed-effects models assessed Time × Condition interactions for performance and recovery outcomes. Passive half-time rest led to significant deterioration in technical skill, sprint performance, and perceived recovery (p < .05) for the control group. TG and PD significantly improved technical performance (LSPT scores) compared to the control group (d = 0.65 and 0.72, respectively; p < .01). Furthermore, TG and COMP were effective at maintaining 20-meter sprint times (d = 0.58 and 0.49; p < .01), whereas the control group experienced significant slowing. Perceived recovery (TQR) scores significantly declined in the CON group from First Half to Second Half (16.5 ± 2.2 to 11.1 ± 2.3. However, this decline was significantly attenuated in all intervention groups: TG (17.5 ± 1.9 to 14.2 ± 1.9), PD (17.3 ± 1.9 to 15.1 ± 1.9), and COMP (17.6 ± 1.9 to 15.9 ± 2.0). Short-duration passive interventions during half-time can mitigate performance decline in adolescent soccer players. TG and EMS appear most effective for preserving technical skills, while COMP may support perceived recovery. These findings highlight practical strategies for optimizing in-game performance and inform evidence-based half-time protocols.

#12 Effects of Soccer Boot Insoles on Muscle Activity and Ankle Inversion Proprioception in Drop Landing Tasks in Patients with and without Chronic Ankle Instability

Reference: J Hum Kinet. 2025 Oct 24:103:27-41. doi: 10.5114/jhk/205685. eCollection 2026 Jul.
Authors: Ratakorn Aimkosa, Oren Tirosh, Charlotte Genderton, Doa El-Ansary, Roger Adams, Jia Han
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13551330/pdf/JHK-103-205685.pdf
Summary: Chronic ankle instability (CAI) poses challenges in sports. Textured insoles are a promising intervention for optimizing ankle muscle activity and enhancing ankle proprioceptive ability in individuals with CAI. This study investigated the effects of different types of insoles on ankle muscle activity and ankle inversion proprioception during drop-landing tasks. Thirty-two soccer players (16 CAI, 16 non-CAI) participated in the study. Electromyographic (EMG) activity of the tibialis anterior (TA), medial gastrocnemius (MG), and peroneus longus (PL) muscles was recorded during drop-landing tasks using the ankle inversion discrimination apparatus for landing (AIDAL) with textured insoles (TI) and standard flat insoles (SI). Ankle inversion proprioception was assessed using the AIDAL. Muscle activity was analyzed for pre- and initial contact phases. CAI players showed significantly reduced TA activity compared to non-CAI players during both pre-initial (2.62 ± 1.86 vs. 5.53 ± 5.15; p = 0.04) and initial contact phases (18.7 ± 13.6 vs. 29.9 ± 20.6; p = 0.01). CAI players also exhibited greater MG activity during pre-initial (16 ± 6.15 vs. 12.5 ± 6.38; p = 0.03) and initial contact phases (60.8 ± 32.5 vs. 41.5 ± 14.8; p = 0.004), and higher PL activity during the pre-initial contact phase (7.39 ± 4.75 vs. 4.28 ± 2.83; p = 0.003). No significant CAI/insole main effects or interactions (p > 0.05) were observed in AIDAL proprioceptive scores. Overall, CAI players showed significant alterations in ankle muscle activity during drop-landing tasks. Increased PL activity during the pre-initial contact phase may serve as a compensatory strategy to enhance ankle stability, while reduced TA and increased MG activation during pre-initial and initial contact phases may contribute to the high incidence of recurrent ankle sprains in CAI individuals. Additionally, the lack of immediate effects from insoles on muscle activity suggests that their influence on sensory input and foot positioning may require prolonged use to induce measurable neuromuscular adaptations.

#13 The Acceleration-Speed Profile in Professional Soccer Players: A Comparative Study According to Sex, the Sports Level and the Playing Position

Reference: J Hum Kinet. 2026 Jul 19:103:149-160. doi: 10.5114/jhk/220252. eCollection 2026 Jul.
Authors: Andrés López-Sagarra, Manuel A Rodríguez-Pérez, Alexis Padrón-Cabo, Andrés Baena-Raya
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13551336/pdf/JHK-103-220252.pdf
Summary: This study aimed to compare maximum acceleration and speed capabilities in professional soccer players, both derived from the acceleration-speed (AS) profile (theoretical maximum acceleration [A0] and speed [S0]) and direct assessment (maximum acceleration [MaxAcc] and speed [MaxSpeed]), according to both (i) sex and the sports level, and (ii) the playing position. A total of 737 professional women and men soccer players were monitored during 5-10 official matches. Data were collected using 18-Hz GPS devices to derive AS profiles and directly measure acceleration and speed output. Across all playing levels, professional men soccer players demonstrated significantly (p < 0.01) higher values than female players for A0 (d = 1.14-1.87), S0 (d = 3.88-4.82), MaxAcc (d = 0.57-1.22), and MaxSpeed (d = 2.46-2.81). Likewise, players of higher sports levels showed superior output than their lower counterparts (First Men’s Division > Second Men’s Division > Under 20 Men’s Division; p < 0.05). Position-specific analysis revealed that midfielders had significantly (p < 0.05) lower MaxSpeed values than other positions such as full-backs (d = 0.63-1.17), wide midfielders (d = 0.82), and forwards (d = 0.67-1.06) in both the First and Second Divisions. Conversely, wide midfielders in the Under 20 Men’s Division exhibited significantly (p < 0.05) higher A0 values than central defenders (d = 0.78). These findings highlight the importance of conducting sex- and position-specific analyses of the AS profile to effectively monitor acceleration and speed capacities across different sports levels in professional soccer.

#14 The Impact of Anthropometric Characteristics and Motor Abilities on Match Running Performance (MRP) in Elite Soccer Players: A Multiple Regression Approach

Reference: J Hum Kinet. 2025 Nov 19:103:227-244. doi: 10.5114/jhk/207525. eCollection 2026 Jul.
Authors: Radivoje Radaković, Borko Katanić, Mima Stanković, Igor Jelaska, Goran Jelaska
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13551338/pdf/JHK-103-207525.pdf
Summary: The aim of the study was to examine the impact of anthropometric characteristics and motor abilities on match running performance (MRP) in elite soccer players. For this purpose, a sample of 41 professional soccer players was evaluated considering five anthropometric characteristics, 11 motor abilities (including sprint and acceleration performance, agility, power, and endurance) as regressors, and six variables describing MRP (time spent in running at < 8 km/h, 8-15 km/h, 15.1-19 km/h, 19.1-23 km/h, > 23 km/h and total time spent in running) as criteria. Regression analysis identified significant regression models (p < 0.05) predicting 8.1-15 km/h, 19.1-23 km/h, and total time spent in running variables for both sets of regressors, with morphology explaining 29.6%, 29.8%, and 37.4%, and motor abilities explaining 59.6%, 65.9% and 68.7% of criterion variables, respectively. It can be concluded that body composition variables such as muscle and fat percentages are associated with jogging, high-speed running, and total distance covered, whilst sprinting variables at 10, 20, and 30 m, the 10/20 index, and the CMJ are associated with jogging and total distance covered. Also, the squat jump is associated with jogging, while shuttle run test performance is associated with high-speed running only. Results provide deep insight into the structure of relationships between MRP and both morphological and motor variables, which are essential to structure advanced training systems focused on optimization of MRP in elite soccer players.

#15 Effects of Dribbling constraints on Sprint Acceleration Performance and the Force-Velocity Profile according to Playing Positions in Professional Soccer Players

Reference: J Hum Kinet. 2025 Nov 20:103:43-56. doi: 10.5114/jhk/204820. eCollection 2026 Jul.
Authors: Dhia Benhassen, Abderrahmane Rahmani, Firas Zghal, Pierre Samozino, Haithem Rebai, Nicolas Peyrot
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13551331/pdf/JHK-103-204820.pdf
Summary: This study aimed to investigate the impact of dribbling on sprint acceleration performance (sprint time) and the associated force-velocity (F-V) profile among professional soccer players across playing positions. Participants (N = 52) were categorized as central defenders (cDs), wide defenders (WDs), central midfielders (cMs), wide midfielders (WMs), and forwards (Fs). A field method based on split times measurements during 30-m sprint acceleration was used to calculate maximal theoretical force (F0) and velocity (V0), maximal power (Pmax) and the F-V slope during sprinting without the ball and while dribbling. Our study revealed a significant decline in sprint performance during dribbling. cDs and WDs exhibited higher losses in 5-m split time (T5; 19%) compared to Fs (13%) and WMs (14%). cMs displayed higher losses in 20-m split time (T20; 11%) compared to Fs (8%). Pmax and F0 significantly decreased when dribbling, with a higher decrease in Pmax experienced by cMs (33%) compared to Fs (24%) and WMs (25%). Similarly, a higher decrease was observed in F0 for cMs (29%) compared to Fs (20%) and WMs (20%). The determination coefficients between the loss in T5 and Pmax (r2 = 0.54), F0 (r2 = 0.62), and the loss in T20 and Pmax (r2 = 0.75), F0 (r2 = 0.23), and V0 (r2 = 0.22) indicated substantial relationships between sprint performance decline and losses in the F-V profile. In conclusion, this study highlights how dribbling affects sprint performance and the F-V profile differently across soccer playing positions. coaches can tailor training programs considering the constraints imposed by dribbling for effective players‘ development.

#16 Vertical Stiffness, Pelvic Tilt Range and Jump Height during Vertical Jumping in Youth Soccer: Influence of Age, Sex and the Playing Position

Reference: J Hum Kinet. 2025 Nov 19:103:69-80. doi: 10.5114/jhk/204868. eCollection 2026 Jul.
Authors: Rafael Martínez, Alejandro Sanz, Florentino Huertas, Paul J Byrne, Javier Martínez-Gramage
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13551353/pdf/JHK-103-204868.pdf
Summary: This study aimed to examine the influence of sex, age, and the playing position on vertical stiffness, pelvic tilt range, and jump height during vertical jumping in young soccer players. A total of 542 players (129 females, 413 males) aged 12 to 19 years from elite soccer academies participated. Players were divided into U14, U16, and U19 categories, and jump height, vertical stiffness, and pelvic tilt range were evaluated using the countermovement jump (CMJ) with an inertial sensor. Results revealed that vertical stiffness and jump height were significantly higher in males than females (p < 0.001) and significantly increased with age in males only from U14 to U16, U16 to U19 and U14 to U19 (p < 0.01 to p = 0.015). Pelvic tilt range was significantly greater in females only (p < 0.001), with forwards showing larger pelvic tilt range than midfielders (p = 0.023), though no differences were found by age. The analysis of the playing position showed no significant differences in vertical stiffness or jump height, suggesting that these variables were more influenced by biological and sex-related factors rather than positional roles during developmental stages. These findings provide normative data that can aid in the design of individualized training programs aimed at optimizing performance and reducing injury risk in youth soccer players.

#17 The Impact of Field Size on Positional and Possession Games: Variations in Physical Demands across Player Positions in Soccer Training

Reference: J Hum Kinet. 2026 Jul 19:103:261-275. doi: 10.5114/jhk/222302. eCollection 2026 Jul.
Authors: Jose Antonio Asian-Clemente, Bernardo Requena, Jose Vicente Beltran-Garrido, Piotr Żmijewski
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13551327/pdf/JHK-103-222302.pdf
Summary: This study investigated how pitch size and a task type (position vs. possession games) influence running demands and external load across player positions in soccer training. Twenty-five young professional soccer players (21.9 ± 1.9 years) participated in 36 training sessions during the 2021-2022 season. Position and possession games were conducted on three pitch sizes (small, medium, large). Players wore GPS devices to measure total distance covered (DC), peak speed, and acceleration/deceleration metrics (low-intensity < ±3 m•s⁻2 and high-intensity > ±3 m•s⁻2). Mixed models assessed the effects of pitch size and a task type on these metrics and positional differences. Possession games elicited higher total DC than position games across all sizes studied (p < 0.005). In the large format, the peak speed was higher in possession than in position games (p < 0.001). On small pitches, possession games resulted in greater low-intensity accelerations/decelerations (ACC<3/DEC<3), but fewer high-intensity accelerations/decelerations (ACC>3/DEC>3) and maximal deceleration compared to position games (p < 0.05). Positional analysis revealed that central defenders and fullbacks reached greater total DC across all three formats of possession games (p < 0.05). Central-midfielders and forwards recorded higher peak speeds in the large possession game (p ≤ 0.01). Wide-midfielders achieved fewer ACC<3 and DEC<3 events in position games during the small format, while fullbacks performed fewer ACC<3 but more ACC>3 in the same format during position games (p ≤ 0.05). Field size and the game format significantly affect external load in soccer. Possession games require greater total DC regardless of size and higher peak speeds on larger fields, while position games involve more high-intensity actions, reflecting players‘ tactical roles.

#18 Comparison of the Most Demanding Periods in Three Categories of Female’s Soccer: A Double View from the Player and the Team

Reference: J Hum Kinet. 2025 Nov 19:103:201-214. doi: 10.5114/jhk/207258. eCollection 2026 Jul.
Authors: Beñat Erkizia, David Casamichana, Fabio Yuzo Nakamura, Eider Barba, Julen Castellano
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13551343/pdf/JHK-103-207258.pdf
Summary: This study is the first to quantify most demanding periods (MDPs) at both the individual (player) and the team level across three teams. It provides reference values for three external load variables across four time windows (of 1, 3, 5 and 10 min). The findings revealed that Professional (PRO) and Reserve (RES) teams covered more distance than the Academy (ACA) team in a 1-min window (w1), with the PRO team also covering greater distances at >18 km•h-1 in the w1. Additionally, PRO and RES teams experienced more accelerations in 1- and 3-min windows, with the PRO team showing higher values than the RES team in the 5-min window (w5). Players in PRO and RES teams ran longer distances and performed more accelerations than those in the ACA team, especially in 1-, 3-, and 5-min windows. No significant differences in MDPs were observed between the first and second halves for any team, but significant differences in distance covered were noted for PRO and ACA players in specific time windows. The main findings highlight superior locomotor and mechanical responses in PRO and RES players compared to ACA players, particularly in shorter time windows (w1, w3, and w5).

#19 High-Dose Caffeine Mouth Rinse Is an Effective Strategy for Isokinetic Strength Generation in Soccer Players

Reference: J Hum Kinet. 2025 Nov 19:103:107-120. doi: 10.5114/jhk/208389. eCollection 2026 Jul.
Authors: Mehmet Vural, Mustafa Ozdal, Cemre Didem Eyipınar, Mete Berk Demiryol
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13551335/pdf/JHK-103-208389.pdf
Summary: Caffeine supplementation is one of the most commonly used ergogenic aids among soccer players. However, research shows conflicting results regarding the effects of different caffeine forms on muscle strength and power. This study investigated the impact of a high-dose caffeine mouth rinse on isokinetic knee extensor and flexor strength of the dominant leg at high (180°/s-1) and low (60°/s-1) angular velocities. Eight young male soccer players were randomly assigned to three conditions. Ten seconds before the isokinetic strength tests, participants either rinsed with an aspartame solution containing 750 mg of caffeine (Experimental), a calorie-free aspartame solution (Placebo) or did not use any solution (Control). Participants continued the mouth rinse for 10 s. Isokinetic strength measurements were performed at angular velocities of 60°/s-1 (5 repetitions) and 180°/s-1 (15 repetitions) in all interventions. Peak torque (Nm), the H/Q ratio, time to peak torque (ms), and average peak torque (Nm) in extension and flexion were analyzed. Data were tested for normality using the Shapiro-Wilk test, followed by one-way ANOVA and LSD post hoc tests (significance set at p < 0.05). According to the results, a significant difference was found in the H/Q ratio and time to peak torque at the angular velocity of 60°/s-1 (p < 0.05, η2 = 0.290; 0.306). At the angular velocity of 180°/s-1, no significant differences were found among the interventions (p > 0.05). These findings suggest that a high dose of the caffeine mouth rinse was effective at the lower angular velocity (60°/s-1), but had no effect on peak torque at the higher angular velocity (180°/s-1).

#20 Collegiate Male Soccer Players Reporting Their Perceived Exertion: Differences in Internal and External Intensity between Different RPE Values and Zones

Reference: J Hum Kinet. 2025 Nov 19:103:133-148. doi: 10.5114/jhk/209543. eCollection 2026 Jul.
Authors: Zheng Li, Shenglei Qin, Xiaotian Li, Dingmeng Ren
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13551355/pdf/JHK-103-209543.pdf
Summary: This study aimed to investigate the association between subjective perception (RPE, sRPE) and objective metrics (TRIMP, average HR and peak HR both expressed as %HRmax, total distance, PlayerLoadTM, acceleration distance > 1 m/s2, and running distance ≥14 km/h) in training monitoring using a repeated-measure design, and to assess the utility of RPE levels (values and zones) in differentiating among particular training intensities. This study used a longitudinal study design. Fifteen collegiate male soccer players (age 19.6 ± 0.8 years, body height 179.1 ± 5.4 cm, body mass 70.8 ± 4.9 kg, BMI 22.1 ± 1.7 kg/m2, body fat rate 10.9 ± 2.3%, HRrest 56.6 ± 8.0, HRmax 194.9 ± 7.3) participated in the study. GPS-based wearable devices and the RPE scale were used to training monitoring. Based on 676 observations from 69 training sessions, a moderate to large correlation was found between the SRPE and internal/external loads (r ranges from 0.34 to 0.60, p < 0.001), while a small to moderate correlation was observed between the RPE and internal/external intensity (r ranges from 0.11 to 0.35, p < 0.001). When distributing training intensity, significant effects were found between RPE values and RPE zones (p < 0.05). Our study provides evidence for understanding the relationship between the subjective load assessment method (RPE and sRPE) and objective methods. Specific ranges of internal and external intensity variables can be divided between RPE value (1-9 AU) and the RPE zone (low, moderate, high).

#21 Sex-related biological variation and mental toughness in soccer: a 2D:4D digit-ratio study of Type a, Type B and Type C classification across playing positions

Reference: Front Behav Neurosci. 2026 Aug 25:20:1934922. doi: 10.3389/fnbeh.2026.1934922. eCollection 2026.
Authors: Hamza Kaya Besler, Gulferi M Yildirim, Sinan Canan, Sinan Seyhan, Görkem Açar, Muhammed Fatih Bilici, Uğur Sönmezoğlu
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13550127/pdf/fnbeh-20-1934922.pdf
Summary: Sex-related variation in psychological traits is usually studied as a categorical male-female contrast, which conflates a grouping variable with the continuous biology underlying it. The second-to-fourth digit ratio (2D:4D) provides a non-invasive marker of the prenatal androgen environment, but its relationship with mental toughness and playing position in soccer remains poorly understood. This study examined the associations between 2D:4D-derived classification, playing position, sex and mental toughness, testing whether mental toughness tracks a continuous sex-related biological index rather than sex category alone. In a cross-sectional design, 270 licensed amateur soccer players (241 men, 29 women; aged 13-35 years) from Denizli, Türkiye, were assessed. Mental toughness was measured with the Sports Mental Toughness Questionnaire (SMTQ). Digit lengths were measured directly on both hands with a calibrated digital caliper, and the two-hand mean ratio assigned each player to one of three operational categories at a cut-off of unity (Type A < 1.00, Type C = 1.00, Type B > 1.00). Data were analysed with one-way and two-way ANOVA with Bonferroni post-hoc comparisons. Type B players reported higher mental toughness (M = 47.36) than Type A (43.85) and Type C (44.24) players, F (2, 267) = 6.70, p = 0.002, η2 = 0.048. Defenders (45.34) scored higher than goalkeepers (41.13; p = 0.021), F (3, 266) = 3.00, p = 0.031, η2 = 0.033. In the two-way model classification remained significant, F (2, 258) = 6.10, p = 0.003, whereas position, F (3, 258) = 2.22, p = 0.086, and the interaction, F (6, 258) = 0.81, p = 0.560, did not. Male players scored higher than female players, t(268) = 1.99, p = 0.047. Mental toughness varied with 2D:4D-derived classification and playing position, and the classification effect ran counter to a simple masculinization account, since the less androgenized Type B profile scored highest. A sex difference was also present, but classification and sex operated in opposing directions and neither was reducible to the other. Types A, B and C are operational classifications, not literal brain categories, and should be interpreted with caution.

#22 When is transformational leadership associated with team commitment? The moderated mediation of intrateam communication and intrinsic motivation among collegiate soccer players

Reference: Front Psychol. 2026 Aug 24:17:1852751. doi: 10.3389/fpsyg.2026.1852751. eCollection 2026.
Authors: Sujin Kim, Inwoo Kim
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13547090/pdf/fpsyg-17-1852751.pdf
Summary: Given the critical role of interpersonal dynamics in competitive collegiate team sports, understanding the psychological mechanisms that foster athlete loyalty is essential for long-term team success. This study investigated the structural relationship between coaches‘ transformational leadership and collegiate athletes‘ affective team commitment, focusing on the mediating role of intrateam communication and the moderating effect of intrinsic motivation. Data were collected from 362 male university soccer players in South Korea. Hayes‘ PROCESS macro (Model 7) was employed to test the proposed moderated mediation model, utilizing 5,000 bootstrap resamples for significance testing. The results indicated that transformational leadership was positively associated with team commitment both directly and indirectly through intrateam communication. Furthermore, the association between transformational leadership and communication was significantly contingent upon the athlete’s level of intrinsic motivation. Simple slope analysis revealed that while the positive association between transformational leadership and communicative dynamics remained positive across all motivation levels, its magnitude was significantly weaker at lower levels (-1 SD) and reached its strongest level at higher levels (+1 SD) of intrinsic motivation. Finally, the integrated moderated mediation model was confirmed, as the strength of the indirect pathway via communication strengthened as motivation rose. Discussion: These findings suggest that intrinsic motivation functions as a psychological catalyst that is linked to a stronger relationship between transformational leadership and a robust communicative environment, ultimately strengthening the emotional bond between athletes and their teams. The results emphasize the importance of considering individual motivational profiles when evaluating transformational leadership strategies relation to team commitment.

#23 The Associations of Wet Bulb Globe Temperature With Match Injury and Concussion Incidence in American Youth Soccer

Reference: Sports Health. 2026 Sep 7:19417381261479669. doi: 10.1177/19417381261479669. Online ahead of print.
Authors: Brandon Merfeld, Kristin Haraldsdottir, John Kohler, Jennifer Sanfilippo, Scott Anderson, Gabriella Lues, Andrew Watson
Summary: The relationship between heat stress and injury risk in youth athletes is unknown. The purpose of the study was to identify the association between wet bulb globe temperature (WBGT) and injury risk in youth soccer athletes. Overall injury incidence would increase, and concussion incidence would decrease with higher WBGT. Prospective cohort study. Level 2. Injury characteristics were recorded by athletic trainers at Elite Clubs National League youth soccer events throughout the United States over 2 years, and WBGT was calculated for each day of each event. The associations of nontime-loss and time-loss injury and concussion incidence with WBGT were assessed through separate negative binomial regression models, adjusted for age and sex. A total of 1584 injuries and 306 concussions were reported from 42 events representing 315,113 player-hours. Injury incidence was 5.0 per 1000 player-hours overall and higher for girls than boys (5.6 vs 4.4 per 1000 player-hours respectively, incidence rate ratio [IRR], 1.38; 95% CI, 1.1-1.7; P ≤ 0.001). Concussion incidence was 0.97 per 1000 player-hours, and girls had a higher concussion incidence than boys (1.20 vs 0.78 per 1000 player hours; IRR, 1.39; 95% CI. 1.0-1.9; P = 0.03). Higher WBGT was associated with a lower incidence of injuries overall (IRR, 0.986; 95% CI, 0.98-0.99; P < 0.01), time-loss injuries (IRR, 0.983; 95% CI, 0.97-0.99; P < 0.01), and concussions (IRR, 0.981; 95% CI, 0.97-0.99; P = 0.01), but not nontime-loss injuries (IRR, 1.00; 95% CI, 0.99-0.99; P = 0.86). In this study of match injuries in youth soccer, we found that a higher WBGT was associated with a decreased incidence in overall injuries, as well as a lower incidence of concussions and time-loss injuries. Further research is warranted to understand the mechanisms behind these relationships, and whether they exist similarly in other athletic populations. Clinical relevance: These results help advance our understanding of environmental injury risk factors in youth soccer to inform decision making by support staff.

#24 Characteristics of EEG activity in soccer players‘ alerting effects under different cues

Reference: Front Psychol. 2026 Aug 21:17:1918092. doi: 10.3389/fpsyg.2026.1918092. eCollection 2026.
Authors: Chuikun Li, Cuilan Wei, Shuai Wu, Yeting Zhang, Qiongjia Yuan
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13541504/pdf/fpsyg-17-1918092.pdf
Summary: Previous studies have found a positive correlation between athletic expertise and the alerting effect; however, few studies have investigated these associations among soccer players. This study employed an alerting task to compare the alerting effect between elite soccer players and novices. We report an ERP study involving 68 participants, which allows us to reexamine the mechanisms underlying alerting. We observed that elite athletes had significantly shorter reaction times on both dual-cue and no-cue trials compared to novices, and found that elite athletes‘ alerting network test scores were significantly higher. Elite soccer players generally exhibited faster reactions, and athletic expertise was positively correlated with cognitive performance. Further analysis revealed that, for elite athletes, the N1 peak amplitude evoked by dual-cue conditions in the central, parietal, parieto-occipital, and occipital regions was larger than that of novices; a similar pattern was observed in the central region for no-cue conditions. For dual-cue conditions, the parietal, parieto-occipital, and occipital regions exhibited smaller N1 peak amplitudes; no between-group differences were found in N1 latency. It was also found that, for the dual-cue condition, elite athletes exhibited smaller P2 peak amplitudes in the frontal, fronto-central, and central regions compared to novices. For the dual-cue condition, the prefrontal, frontal, fronto-central, and central regions exhibited larger P2 peak amplitudes. Additionally, the P2 latency for the dual-cue condition was earlier than for the no-cue condition, though no intergroup differences were observed. The results indicate that elite soccer players exhibit significant behavioral and neurophysiological advantages, further demonstrating that the enhancement of N1 and the attenuation of P2 are associated with soccer skill level. Elite soccer players exhibited larger N1 amplitudes and smaller P2 amplitudes in response to both dual-cue and no-cue stimuli. In summary, this study confirms that elite soccer players possess dual advantages in alerting function, providing new empirical evidence for understanding the neuroplasticity mechanisms by which long-term athletic training shapes cognitive function.

#25 Hormonal status, maturation, anthropometry and motor performance in young football players: the advantage of early maturation

Reference: Res Sports Med. 2026 Sep 10:1-20. doi: 10.1080/15438627.2026.2729037. Online ahead of print.
Authors: Sasa Markovic, Tatjana Trivic, Dejan Javorac, Slavko Molnar, Zeljko Sekulic, Nemanja Zlojutro, Patrik Drid
Summary: This study investigates differences in hormonal status, anthropometric measurements, technical skills, and motor performance among young football players across different stages of biological maturation. A total of 261 male players aged 11 to 14 from Bosnia and Herzegovina were divided into two competitive age groups: younger (11-12 years, 12.20 ± 0.57 years) and older (13-14 years, 14.23 ± 0.52 years). Skeletal age was determined using the Greulich-Pyle method. The players were evaluated for chronological age, skeletal age, age peak height velocity, body composition, hormonal levels (DHEA-S and IGF-1), sprint performance, agility, jumping ability, soccer-specific technical skills, and endurance capacity. Data were analysed using IBM SPSS Statistics, including descriptive statistics, ANOVA, t-tests, and effect size (η2), with p < 0.05. In the younger group (11-12 years), significant differences were found in skeletal age, APHV, height, weight, body mass index (BMI), body fat percentage, and hormonal levels (DHEA-S, IGF-1). However, no significant differences were observed in motor performance. In contrast, the older group (13-14 years) demonstrated significant maturation-related differences, including sprint performance, agility, and jump tests. Early maturation provides a significant advantage in anthropometric and motor performance, particularly among older players, and should be considered in talent identification and selection processes.

#26 Association between knee morphometric parameters and non-contact anterior cruciate ligament rupture in professional male football players: a case-control MRI study

Reference: Res Sports Med. 2026 Sep 10:1-16. doi: 10.1080/15438627.2026.2730383. Online ahead of print.
Authors: Yener İnce, Muhammed Yusuf Afacan, Goker Utku Deger, Tolgahan Korkmaz
Download link: https://www.tandfonline.com/doi/epdf/10.1080/15438627.2026.2730383?needAccess=true
Summary: Morphological characteristics of the knee have been widely investigated as potential risk factors for anterior cruciate ligament (ACL) injury; however, the findings remain controversial. Most previous studies have evaluated heterogeneous populations with varying levels of physical activity. The aim of this study was to investigate the association between knee morphometric parameters and non-contact ACL rupture in a sport-specific population of professional male football players. Clinical and radiological data of professional football players evaluated between 2020 and 2025 were retrospectively analysed. Athletes with non-contact ACL rupture confirmed by clinical examination and magnetic resonance imaging (MRI) were included in the ACL rupture group, whereas athletes with normal clinical and MRI findings were included in the control group. Lateral tibial slope (LTS), medial tibial slope (MTS), global tibiofemoral rotation angle (TFRA), notch outlet length (NOL), tibial spine width (TSW), and notch width index (NWI) were measured on MRI. A total of 81 professional male football players were included, consisting of 40 athletes with ACL rupture and 41 controls. The mean ages of the patient and control groups were 23.65 ± 5.41 and 23.68 ± 4.95 years, respectively (p = 0.857). No statistically significant differences were observed between groups in terms of tibial slope measurements, tibiofemoral rotation angle, notch outlet length, or tibial spine width (p > 0.05). However, the NWI was significantly lower in the ACL rupture group, with a mean between-group difference of 1.38 percentage points (95% CI, 0.57-2.18; p = 0.001), and was approximately equal to the estimated minimal detectable change (MDC95 = 1.48). In multivariable analysis, a lower NWI remained associated with ACL rupture (adjusted OR = 0.677; 95% CI, 0.519-0.883; p = 0.004), and ROC analysis showed moderate discrimination (AUC = 0.700, 95% CI, 0.584-0.810). A relatively smaller intercondylar NWI was associated with non-contact ACL rupture in professional male football players. However, this finding should be interpreted as a population-level association rather than evidence of causality or individual predictive value. The other evaluated knee morphometric parameters were not significantly associated with ACL rupture in this sport-specific population.

#27 Rectus femoris scarring as a marker of greater muscle injury risk in young football players: a prospective observational study

Reference: Sci Med Footb. 2026 Sep 10:1-12. doi: 10.1080/24733938.2026.2726162. Online ahead of print.
Authors: Massimo Magistrali, Nicola A Maffiuletti, Carles Pedret, Luca Stefanini, Andrea Marchini, Francesco Mariani, Marco A Minetto
Summary: The objective of the present study was to assess whether the presence and characteristics of ultrasound-detected rectus femoris (RF) scars were associated with a greater risk of subsequent muscle injuries. In this prospective cohort study conducted over two consecutive competitive seasons in a professional football Club, all available players from the male Under-15 to Under-19 and Second Team underwent standardized ultrasound screening at the beginning of each competitive season. Scar presence, laterality, number, size and involvement of tendons or aponeuroses (MT scars) were recorded, along with a detailed injury history. Players were prospectively followed and time-loss muscle injuries were systematically recorded. A total of 176 players were included, accounting for 262 player-seasons; in 62 (24%) at least 1 RF scar was present. Players with scars showed higher muscle injury incidence compared with scar-free players (p < 0.01). Among players with RF scars, those with MT involvement showed a higher injury incidence (p = 0.047). When adjusting for age and previous injury, the association between the presence of RF scars and increased injury incidence was substantially reduced (p = 0.35). This association was also attenuated for MT scars (p = 0.08), which conversely showed an association with a shorter time to first injury (p = 0.02). In conclusion, the presence of RF scars was associated with a higher overall incidence of muscle injuries, but not after adjustment for age and previous injury. The presence of MT scars identified a subgroup of players in which this association was particularly marked. This finding should be considered exploratory and warrants further investigation in future studies.

#28 Trends in Semiprofessional Scottish Football Players‘ Acceleration and Deceleration Loads Across Playing Positions During Competitive Play and Training

Reference: Transl Sports Med. 2026 Sep 9:2026:6295249. doi: 10.1155/tsm2/6295249. eCollection 2026.
Authors: Mark Farrell, Judith V Lane, Prateek Rangra
Download link: https://onlinelibrary.wiley.com/doi/epdf/10.1155/tsm2/6295249
Summary: High-intensity accelerations (HIAccs) and high-intensity decelerations (HIDecs) are critical to football performance, yet little is known about their demands in semiprofessional contexts where training frequency and resources differ from the professional game. This study quantified HIAcc and HIDec loads during competitive match play and training across playing positions in semiprofessional Scottish football. Thirty-three players were monitored over two competitive seasons (2021-2023) using 10-Hz Global Positioning System (GPS) devices, generating 1333 individual observations. Linear mixed models assessed total distance, frequency and peak magnitude of HIAcc and HIDec at two intensity thresholds (3-4 m/s2 and > 4 m/s2) across playing positions and session types (MD-4, MD-2 and match day). Position (p < 0.001) and session type (p < 0.001) significantly influenced HIAcc and HIDec demands. Full-backs recorded the highest deceleration loads, particularly > 4 m/s2, whilst wide midfielders accumulated greater acceleration distances than central players. MD-4 sessions often exceeded match-day acceleration values (106%-120%), whereas match days consistently imposed higher deceleration demands. These patterns diverged from those reported in professional cohorts. Semiprofessional players display distinct positional and session-specific loading patterns compared with professional football. Tailored, position-specific training and modified periodisation strategies appear necessary to align training with the physical demands of competition in this population.

#29 Extended Inflammatory Osteitis Pubis With Associated Myositis and Femoral Neuropathy in an Amateur Football Player: A Case Report

Reference: Clin Case Rep. 2026 Sep 9;14(9):e73467. doi: 10.1002/ccr3.73467. eCollection 2026 Sep.
Authors: Sousan Kolahi, Mojtaba Varshochi, Sepideh Tahsini Tekantapeh, Mohammad Mahdi Tehrani Ghadim, Amirreza Jahanshahi
Download link: https://onlinelibrary.wiley.com/doi/epdf/10.1002/ccr3.73467
Summary: A 42-year-old male amateur football player presented with a 17-day history of progressive groin pain, primarily on the right, radiating to the perineum, associated with limitation of hip motion. Because of proximal weakness and elevated inflammatory markers, polymyositis and an infectious process were initially suspected. Electromyography demonstrated a subacute incomplete axonal lesion of the right femoral nerve likely due to iliopsoas compression. Joint aspiration yielded purulent-appearing fluid with 850 WBC/mm3 and 80% PMNs, although cultures remained negative. MRI demonstrated bone marrow edema at the pubic symphysis, fluid collections in the adductor and iliacus muscles, right iliopsoas bursitis, and mild hip effusion, supporting a diagnosis of osteitis pubis with associated inflammatory myositis and bursitis rather than primary infection or polymyositis. Empirical antibiotics and corticosteroid therapy resulted in clinical and laboratory improvement. This case highlights the diagnostic challenge of osteitis pubis presenting with femoral neuropathy and inflammatory findings that may mimic infectious or inflammatory myopathy.

#30 Ramadan Intermittent Fasting and Injury Epidemiology in Mid and Late Adolescent Elite Male Football Players: A Prospective Cohort Study of Incidence, Burden, Training Load, and Psychophysiological Well-Being

Reference: 2026 Oct;26(10):e70249. doi: 10.1002/ejsc.70249.
Authors: Noureddine Rejab, Fatma Chaari, Mohamed Ali Nabli, Sonia Sahli, Haithem Rebai
Download link: https://onlinelibrary.wiley.com/doi/epdf/10.1002/ejsc.70249
Summary: This study investigated the influence of Ramadan fasting on injury incidence, training load, subjective well-being, postural control, and dietary intake in competitive mid- and late elite male adolescent football players across three study phases. A prospective observational cohort design was employed over 13 consecutive weeks in 101 elite male youth football players (U17, n = 56; U19, n = 22; U21, n = 23). Three phases were identified: Pre-Ramadan (Weeks 1-4), Ramadan (Weeks 5-8), and Post-Ramadan (Weeks 9-13). Weekly session-RPE training load, Hooper Index, anthropometrics, and 3-day dietary records were collected prospectively. Injury surveillance was conducted according to the UEFA guidelines. Forty-six players (45.5%) sustained ≥ 1 time-loss injury over 10.419.3 h of exposure. Injury incidence increased during Ramadan from 3.76 to 6.83/1.000 h (RR = 1.816, 95% CI: 0.904-3.651; + 81.6%), with injury burden doubling from 55.16 to 111.68 days/1.000 h (+102.5%). Perceived training load (+134.3 AU; χ2 = 106.77, p < 0.001; d = 1.79) and Hooper Index (+1.99 points; χ2 = 122.16, p < 0.001; d = 8.97) increased significantly. Muscular injuries represented 69.6% of Ramadan injuries, while osseous injuries occurred exclusively during Ramadan. Protein intake decreased (26.30%-23.01%; p < 0.001; d = 3.68), with increased carbohydrate contribution (49.36%-54.13%; p < 0.001). Ramadan intermittent fasting was associated with a clinically significant elevation in injury incidence and burden in mid- and late elite male adolescent football players, occurring concurrently with increased perceived training load, progressive psychophysiological deterioration, and reduced dietary protein intake. These findings underscore increased injury risk during Ramadan and the need for tailored prevention.

#31 Optimizing football analytics: Dimensionality reduction meets machine learning for offensive and defensive player profiling

Reference: PLoS One. 2026 Sep 9;21(9):e0353239. doi: 10.1371/journal.pone.0353239. eCollection 2026.
Authors: Rodrigo Yáñez-Sepúlveda, Aldo Vásquez-Bonilla, Rodrigo Olivares, Pablo Olivares, Guillermo Cortés-Roco, Eduardo Guzmán-Muñoz, Marcelo Tuesta, Jorge Olivares-Arancibia, Boryi A Becerra-Patiño, Juan David Paucar-Uribe, Diego Andrés Rada-Perdigón, Exal Garcia-Carrillo, Tomás Rivera-Kofler, Vicente Javier Clemente-Suárez, José Francisco López-Gil
Download link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0353239
Summary: This study focuses on the quantitative analysis of football players‘ performance based on a set of performance data. The objective of this study was to develop a multivariate analytical model to identify, quantify, and predict the most relevant factors that determine the offensive and defensive profiles of professional football players, thereby optimizing functional segmentation, performance analysis, and decision-making processes in the contexts of scouting and data-based tactical planning. Materials and A dataset was compiled through automated extraction (web scraping) via the Python programming language and its specialized libraries. The full dataset comprised 2,689 player-league records corresponding to 2,530 unique players from Europe’s five major UEFA-affiliated national leagues during the 2022-2023 season (159 players who transferred between two leagues mid-season contributed one record per league, 2,530 + 159 = 2,689). After applying a minimum-eligibility filter of >450 minutes played to ensure stable per-90 metrics, 1,624 player-league records (1,620 unique players) were retained for the modeling workflow. Dimensionality reduction techniques (PCA) and explainable machine learning (Shapley Additive exPlanations [SHAP]) with predictive modeling were applied. Eight algorithms were trained and compared to predict PC1 Offensive and PC1 Defensive. The First Offensive Principal Component (PC1 Offensive) synthesizes actions that generate scoring opportunities, such as actions prior to shots (SCA_p90, 13.3%), progressive receptions (RecProg_p90, 13.0%) and total shots (Shots_p90, 12.7%). The first-defensive principal component (PC1 Defensive) highlights tackles (Tkl_p90, 19.1%), blocks (15.6%) and interceptions (15.6%). Finally, the inclusion of SHAP allows for an in-depth interpretation of the models, identifying the key statistical factors that influence players‘ offensive and defensive contributions, which is valuable for scouting, tactical analysis and player development.

#32 Association between dietary intake, energy availability, and recovery in young sub-elite Moroccan football players

Reference: J Int Soc Sports Nutr. 2026 Dec 30;23(1):2730213. doi: 10.1080/15502783.2026.2730213. Epub 2026 Sep 9.
Authors: El Mahdi Ait Aammi Hadi, El Mokhtar El Ouali, Anass Akhittouch, Hiba Rimy, Fadwa Zehhaf, Khalid Kassimi, Aziz Chokri, Abdeljalil Elgot, Mohamed Barkaoui
Download link: https://www.tandfonline.com/doi/epdf/10.1080/15502783.2026.2730213?needAccess=true
Summary: Energy availability is recognized as an important factor for health and performance in athletes, yet data in male football players and its relationship with post-exercise recovery remain limited. This study aimed to examine the associations between daily energy intake, energy availability, and recovery outcomes in football players. Nineteen outfield U21 players (n = 19) from a national championship in Morocco were monitored over four in-season weeks. On one training day, one rest day and one official match day per week, players completed 24-h dietary recalls, from which energy intake and macronutrient intake were quantified using Nutrilog software. Exercise energy expenditure was estimated and energy availability was calculated. Internal load was assessed using session rating of perceived exertion, subjective recovery with the Perceived Recovery Status scale 24-h post-session, and neuromuscular recovery via countermovement jump height. Mean daily EI did not differ significantly between match, training, and rest days (p = 0.066), whereas EA was significantly lower on training days compared with match and rest days (both p ≤ 0.003). Higher EA was strongly associated with lower RPE (ρ = -0.597, p < 0.001) and modestly with higher PRS (ρ = 0.273, p = 0.001), while its association with CMJ was small and non-significant (ρ = 0.124, p = 0.132). Higher EI showed a moderate inverse correlation with RPE (ρ = -0.404, p < 0.001) and a small positive correlation with PRS (ρ = 0.173, p = 0.035), but no significant association with CMJ. Across EA categories, RPE, PRS and CMJ all differed significantly (p ≤ 0.014). Inadequate fueling relative to training demands leads to reduced EA, particularly on training days, and is associated with a lower recovery profile. Monitoring EA alongside simple field-based markers such as RPE and PRS may help practitioners identify periods of suboptimal fueling and adjust nutritional strategies accordingly.

#33 Visual, visuomotor, and kinesthetic abilities in football players: their relationship with sport-specific performance and trainability

Reference: 2026 Aug 24:20:1930426. doi: 10.3389/fnins.2026.1930426. eCollection 2026.
Authors: Congcong Weng #, Dongxu Gao #, Xiushen Dong #, Yuqing Gao, Qiangquan Wang, Jiayu Wang, Junzhe Zou, Lihao Shan, Honglei Zhang
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13548078/pdf/fnins-20-1930426.pdf
Summary: Success in football (soccer) rests on physical and technical capacity and on the perceptual and sensorimotor systems that let players read the game, act quickly, and control the body and the ball. This review examines three linked ability domains: visual (the quality and use of visual input, from static and dynamic acuity to peripheral awareness, object tracking, and visual search), visuomotor (the coupling of perception to action, including reaction time, eye-foot coordination, and visually guided movement), and kinesthetic (proprioception, joint position sense, kinesthetic differentiation, and balance). For each domain we ask how it is measured, how it relates to match-relevant performance, and whether it can be trained. Football players generally outperform non-athletes, and several markers separate players by level, position, and age. Trainability is consistent for targeted laboratory measures across stroboscopic, light-based, augmented-feedback, perceptual-cognitive, and proprioceptive-coordinative programs, but transfer to on-field performance is weaker and less certain, and laboratory tests frequently fail to predict in-game behavior. We argue that the three domains form a single perception-action continuum rather than separate capacities, that assessment and training should represent real match demands, and that sex, limb dominance, maturation, fatigue, and injury status act as moderators. Adequately powered, field-validated trials remain the decisive next step. Practical implications for talent identification, monitoring, and training design are set out. The evidence base is drawn overwhelmingly from male players, so these conclusions apply to men’s football unless otherwise stated.

#34 Analysis of professional football players‘ sprint performance efficiency in matches

Reference: J Exerc Rehabil. 2026 Aug 26;22(4):158-166. doi: 10.12965/jer.2652496.248. eCollection 2026 Aug.
Authors: Jeong-Hyun Shim, Chang-Hwa Joo
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13547613/pdf/jer-22-4-158.pdf
Summary: The purpose of this study is to analyze the efficiency of the high-intensity exercise performances of professional players during matches. Thirty professional players competed in a total of 38 matches throughout the season. 1,558 sprint efforts were recorded and subsequently analyzed. The sprint efficiency assessment tool ensured good interrater reliability (intraclass correlation coefficient, 0.892; 95% confidence interval, 0.883-0.901) and the validity of the analysis was confirmed by four experts with more than 20 years of experience in football. The total distance and low-intensity running were higher during the first half than during the second half of the season (P<0.01). The positions covering the greatest distances were full back and midfielder. High-intensity running (P<0.05) and sprinting (P<0.01) were higher during home matches than during away matches. The sprint efficiency was higher during the second half than during the first half of the season (P<0.05), but the maximum velocity was higher during the first half of the season (P<0.01). Sprint efficiency was higher for the attack than for the defense and defensive transition situations (P<0.05). Higher duration, distance, and maximum velocity were observed for the excellent efficiency group than for the appropriate group (P<0.05). In conclusion, the findings of this study suggest that the development of effective training programs to enhance high-intensity exercise performance, such as sprinting, requires consideration that goes beyond simply physical speed enhancement to encompass situational judgment, timing, path selection, and speed regulation in an integrated way.

#35 Evaluation of factors influencing food choices among Lebanese weightlifters and football players

Reference: J Int Soc Sports Nutr. 2026 Dec 30;23(1):2706009. doi: 10.1080/15502783.2026.2706009. Epub 2026 Sep 7.
Authors: Anna-Maria Al Dannaoui, Caroline Rajeh, Ali Chalak, Elie-Jacques Fares, Ammar Olabi
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13552282/pdf/RSSN_23_2706009.pdf
Summary: Athletes are required to make optimal food choices to maintain a healthy diet and maximize performance. However, they often struggle to effectively translate nutritional recommendations into suitable dietary choices. This study aimed to examine the food choices of Lebanese male athletes, focusing on weightlifters (n = 30) and football players (n = 30) on both rest and workout days, in a free choice setting at a university cafeteria. Participants completed a 24-hour dietary recall interview on their rest and workout days, allowing energy, macro, and micronutrient intake estimation, and filled in a food choice questionnaire to explain motivations behind their lunch selections. Significant differences (p < 0.05) in protein, cholesterol, and vitamin D were observed between weightlifters and football players on workout days. Weightlifters showed significant variations in energy, protein, fats, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), calcium, potassium, and vitamin D across days, while football players displayed significant changes in energy and carbohydrate intake. On rest days, weightlifters chiefly based their food choices on nutritional content (33%), sensory appeal (26%), and familiarity (21%), with similar patterns on workout days. Football players prioritized familiarity (33% on rest days, 21% on workout days), nutritional value, and sensory attributes, showing a slight shift towards nutrition on workout days. The study highlights a gap in adherence to nutritional guidelines among Lebanese athletes, suggesting the need for targeted nutrition strategies tailored to sport type and daily demands that account for food choice motivations.

#36 A new match-heading index for male professional football players based on objective and video sources – SoccHealth

Reference: Sci Med Footb. 2026 Sep 6:1-9. doi: 10.1080/24733938.2026.2727018. Online ahead of print.
Authors: Hansjörg Baurecht, Jürgen Wellmann, Michael J Stein, Michael F Leitzmann, Mike Abroscheit, Claus Reinsberger, Werner Krutsch, Tim Meyer, Klaus Berger
Summary: Repetitive heading of the ball is a distinctive feature of professional football (soccer) and has been discussed as a potential long-term risk factor for neurodegenerative disease. Epidemiologic investigation is limited by the absence of valid methods to quantify heading exposure across a player’s career. To provide a tool for estimating the heading frequency in male professional football players for epidemiological studies where detailed career histories exist but sufficient individual heading exposure data are lacking. Detailed career histories of former male football players were combined with position-specific heading rates derived from two systematic video analyses spanning multiple decades and league levels in Germany. Season-specific heading rates were estimated using natural cubic splines by position, league level, seasons, and combined with playing time to calculate cumulative exposure. Heading rates varied substantially by position and changed markedly over time. In the absence of a gold standard, the plausibility of the match-heading index was evaluated in the SoccHealth project using negative control outcomes. The cumulative heading index showed no association with negative control outcomes (body mass index and handgrip strength), while expected age-related associations remained, which may be interpreted as consistent with the index’s plausibility. We present a novel match-heading index that can be combined with objective career-history data to estimate cumulative career-long match-heading exposure in former male football players. By integrating objective video-based data with detailed career histories and accounting for temporal and positional variation, this approach substantially improves exposure assessment for future epidemiologic studies of long-term neurological outcomes in football players.

#37 Beyond the youth success trap: a Four-Gate Coaching Audit of Japan’s 2017 U20 football cohort

Reference: Front Sports Act Living. 2026 Aug 21:8:1894940. doi: 10.3389/fspor.2026.1894940. eCollection 2026.
Authors: Rui Chen, Shiyan Sheng, Xiaoyu Liu
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13541752/pdf/fspor-08-1894940.pdf
Summary: Youth tournament success is visible, but it is not itself evidence of later adult access, elite club exposure or senior national-team contribution. Coaching departments therefore require source-traceable follow-up after selection. This methodological case study introduces a proof-of-concept Four-Gate Coaching Audit for converting a youth selection event into a longitudinal, player-level evidence register. The audit is a monitoring protocol rather than a validated prediction model. It separates four non-substitutable constructs: documented selection context, post-youth adult competitive access, club-only Post-Youth Elite Exposure (PEEX) and Senior Contribution Ladder (SCL) status. Codes are assigned only from official federation, competition, league or club records; unestablished evidence is coded as NE rather than zero. The demonstration uses the complete 21-player final participant cohort of Japan at the FIFA U-20 World Cup Korea Republic 2017. Tournament-time foreign-club exposure was confirmed for 1/21 players (4.8%), whereas post-youth adult competitive access was officially verified for all 21 players. Under the primary strict senior-tournament rule, SCL-3/4 was confirmed for at least 6/21 players (28.6%); under a broader rule including played Copa América 2019 minutes, this increased to 9/21 (42.9%). Club-only PEEX-3/4 was confirmed for at least 10/21 players (47.6%) after official-source reconciliation. Raw intercoder agreement was high, but source reconciliation still corrected evidence-sensitive classifications, supporting the need to distinguish reliability from endpoint verification. Discussion: The study contributes a construct-separating audit protocol for monitoring youth-to-senior pathways without treating youth selection, overseas registration or senior-team association as automatic evidence of conversion. The findings are official-confirmed minimums and do not imply causal effects, player-quality rankings or national-system superiority.