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 Influence of stimulus material and effector specificity on performance in the measurement of interference control in adolescent handball and soccer players compared to non-player controls
Reference: Psychol Res. 2026 Jun 15;90(3):116. doi: 10.1007/s00426-026-02327-0.
Authors: Florian Heilmann, Leif E Langsdorf, Torsten Schubert
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13269514/pdf/426_2026_Article_2327.pdf
Summary: This study investigated how stimulus material and effector specificity influence interference control (a form of inhibitory control) in adolescent players. Ninety-one males aged 15-18 years (28 handball players, 34 soccer players, 29 non-player controls) completed nine modified Flanker task versions varying in stimulus type (abstract, handball-specific, soccer-specific) and response modality (finger, hand, foot). Mixed-design ANOVAs revealed significant main effects of congruency, stimulus type, and response modality. Responses were slower, and interference effects were larger in incongruent than in congruent trials. In addition, sports-specific stimuli and more motorically demanding response modalities were associated with increased response times compared to abstract arrow stimuli and simple finger responses. A congruency × stimulus interaction revealed reduced flanker effects for sports-specific stimuli, indicating that domain-specificity shapes interference processing. However, no consistent group differences were found, suggesting adolescent players do not exhibit broad cognitive advantages, or such advantages are context-dependent. Overall, the findings suggest that performance was primarily shaped by perceptual and motor requirements of the task, i.e., bystimulus complexity and response modality rather than by differences between athlete and control groups. Longitudinal research is needed to clarify how training and development interact to shape cognitive-motor control.
#2 Ultrasound Screening for Cam Morphology in Male University Soccer Players: Prevalence and Association With Groin Symptoms and Functional Impairments
Reference: Orthop J Sports Med. 2026 Jun 12;14(6):23259671261445433. doi: 10.1177/23259671261445433. eCollection 2026 Jun.
Authors: Masayoshi Saito, Hajime Utsunomiya, Riko Yamashita et al.
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13263483/pdf/10.1177_23259671261445433.pdf
Summary: Ultrasound (US) screening for cam morphology in athletes is rarely performed. Conventional US imaging in the neutral hip position may overlook cam lesions in the anterolateral position, which is the most common location that exhibits cam morphology. The purpose was to investigate US-detected cam-related morphology and prominence in male collegiate soccer players using US with an additional 15° hip extension view and to examine their associations with groin symptoms and functional impairments. This voluntary screening study included 55 male collegiate soccer players (110 hips; mean age, 19.5 ± 1.1 years) from a single varsity team, all of whom were active and without hip or groin pain severe enough to limit soccer participation. US imaging of the femoral head-neck junction was performed in the neutral position and at 15° of hip extension using a linear probe. The femoral morphology on US was classified as normal, flattened, or prominent; and flattened or prominent findings were grouped as cam-positive for analysis. Groin pain and pinching sensations were assessed using questionnaires and flexion adduction internal rotation tests. Four functional parameters were evaluated, and logistic regression analyses were performed to identify factors associated with the current symptoms. US-based cam-positive morphology was identified in 97 hips (88%) and prominence in 53 hips (48%). The detection rate of US-based cam-positive morphology increased from 79% at 0° to 88% at 15° of hip extension (P = .02), and that of prominence increased from 21% to 48% (P < .0001). Groin pain was present in 25 hips (19%), and pinching sensation was reported with 49 hips (45%). In cam-positive hips, having ≥3 functional deficits (odds ratio [OR], 5.0) and greater side-to-side internal rotation difference (OR, 1.2) predicted groin pain; the same variables (OR, 10.2 and 1.1, respectively) predicted pinching sensation. In prominence-positive hips, ≥3 functional deficits predicted groin pain (OR, 6.5) and pinching sensation (OR, 6.9). US screening with 15° hip extension improved the detection of anterolateral cam-related morphology in male collegiate soccer players. Current symptoms were more strongly associated with multiple functional impairments than with morphology alone.
#3 Reliability and sensitivity of mechanical properties of phase-specific during the 505-test using a radar device in soccer players
Reference: Front Physiol. 2026 May 29:17:1840593. doi: 10.3389/fphys.2026.1840593. eCollection 2026.
Authors: Jin Li, Hongxing Li, Fan Gu, Ying Li, Ruiqi Cheng, Lin Song, Christophe Hautier, Qingshan Zhang
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13261173/pdf/fphys-17-1840593.pdf
Summary: Change-of-direction (COD) ability is a key determinant of soccer performance. This study evaluated the intra- and inter-day reliability and sensitivity of a single-radar device (SRD) for capturing phase-specific kinetics and kinematics during the 505 tests in 24 youth soccer players. Intra-day results showed high reliability for maximum velocity (Vmax, ICC = 0.67, CV = 1.51%) and moderate-to-high reliability for kinetic variables (P2_HBF avg and P3_HAP avg, ICC = 0.58-0.59). However, all intra-day metrics exhibited „Marginal“ usefulness as Typical Error (TE) consistently exceeded the Smallest Worthwhile Change (SWC). In contrast, inter-day reliability was substantially higher, particularly for kinetic indicators such as braking impulse (P2_HBI avg, ICC = 0.90) and re-acceleration force (P3_HAF max, ICC = 0.91). Furthermore, inter-day assessment revealed „Good“ usefulness (TE≤SWC) for key metrics, including P2_HBIavg, P3_HAFavg/max, and re-acceleration distance/velocity. These results indicate that while intra-day stability is limited by movement variability, RRDs provide sufficient precision for individualized monitoring across testing days. Practitioners should prioritize inter-day kinetic profiles and incorporate familiarization to maximize diagnostic accuracy in youth soccer populations.
#4 Effects of adaptive error-threshold practice on soccer instep kick learning
Reference: Sci Rep. 2026 Jun 13. doi: 10.1038/s41598-026-57684-y. Online ahead of print.
Authors: Hossein Taghizadeh, Davoud Fazeli, GholamHossein Nazemzadegan
Download link: https://www.nature.com/articles/s41598-026-57684-y_reference.pdf
Summary: This study examined the effects of contextual interference and algorithmic practice with 33% or 44% error thresholds on learning the soccer instep kick in novice participants. Seventy-one inexperienced students (18-25 years) were randomly assigned to Blocked, Random, algorithmic 33%, algorithmic 44%, or control groups. After pre-testing, practice involved 324 trials over two days from 5, 6, and 7 m distances. Algorithmic groups began with blocked practice and progressed to serial or random structures based on accuracy thresholds (≥ 67% for 33%; ≥ 56% for 44%). Blocked and random groups practiced according to classical random and blocked order. Retention and transfer tests occurred two days post-practice; psychological pressure was induced via financial incentives, audience, and social comparison. Acquisition results showed no group differences, but algorithmic 33% improved significantly from day 1 to 2. In retention, both algorithmic groups outperformed random and control groups. In the transfer test, algorithmic 44% surpassed all groups, including algorithmic 33%. Heart rate increased post-stress induction, confirming manipulation success, yet no group differences emerged under psychological pressure. The findings may be interpreted within the challenge point framework, although the underlying informational mechanisms were not directly assessed. As an initial application of algorithmic practice to a field-based motor skill, the present results suggest that error-threshold tuning may represent a promising avenue for future motor learning research.
#5 Temperature and aggression revisited: Evidence from 1 million amateur football matches
Reference: PNAS Nexus. 2026 Jun 12;5(6):pgag202. doi: 10.1093/pnasnexus/pgag202. eCollection 2026 Jun.
Authors: Sascha Riaz, Maurice Baudet von Gersdorff, Heike Klüver
Summary: A large body of research documents a positive relationship between temperature and human aggression, underpinning projections of increased conflict in a warming climate. However, most prior evidence relies on laboratory experiments with convenience samples or on crime records, both of which are limited in their generalizability to everyday social interactions. To isolate the effect of temperature in a standardized, real-world social environment, we analyze ∼1 million amateur football matches played across Germany and study aggression among more than one million amateur players. Comparing matches played at the same venue within the same league and season, and adjusting for referee and team differences, we find a precisely estimated inverted-U relationship between temperature and player aggression: disciplinary cards (issued by referees for fouls and misconduct) increase with temperature up to ∼13 °C but decline thereafter. Matches played under extreme heat show a 15% reduction in disciplinary actions relative to the sample mean. Our results contribute to the temperature-aggression literature: in line with affect-based accounts of aggression, moderate warmth may increase irritability and arousal; however, to the extent that aggressive behavior requires physical engagement, it may decline at extreme temperatures.
#6 Impact of a school based flag football intervention on fitness outcomes in Chinese children aged 9 to 11 years: a randomized controlled trial
Reference: BMC Public Health. 2026 Jun 18. doi: 10.1186/s12889-026-28081-x. Online ahead of print.
Authors: Junyu Wang, Dongning Liu, Yixin Liang et al.
Download link: https://link.springer.com/content/pdf/10.1186/s12889-026-28081-x_reference.pdf
Summary: The aim wa to evaluate the effects of a 10-week school-based flag football programme on fitness outcomes in Chinese children aged 9 to 11 years. A two-arm, parallel-group randomized controlled trial was conducted in a public primary school in Shanghai, China. Children (n = 147) were randomized to either flag football (n = 74; mean age, 9.7 ± 0.5 years; 30 girls) or usual physical education (PE; n = 73; mean age, 9.7 ± 0.5 years; 32 girls). The intervention comprised 60-min sessions, delivered twice weekly for 10 weeks. Outcomes were assessed at baseline and post-intervention: the 20 m shuttle run test (laps), estimated maximal oxygen uptake (VO₂max), the 1-min jump rope test (turns), and the 50 m dash (seconds). Primary analyses followed the intention-to-treat principle using multiple imputation and repeated-measures models; subgroup analyses were conducted by sex and baseline weight status. Session intensity was monitored through heart rate (HR) in a subsample. Post-intervention data were available for 128 children (87.1%). Compared with usual physical education, the flag football group showed greater improvements in 1-min jump rope performance (between-group difference in change = 7.4 turns; p = 0.03) and 50 m dash time (between-group difference in change = -0.3 s; p = 0.013). No between-group differences in change were observed for 20 m shuttle run performance (0.7 laps; p = 0.32) or estimated VO2max (0.19 mL·kg-1·min-1; p = 0.37). Subgroup analyses revealed the most significant effects in boys with normal weight for estimated VO2max and 20 m shuttle run, boys across BMI status groups for sprint performance, and girls across BMI status groups for jump rope. A PE-embedded flag football programme effectively improved sprint speed and 1-min jump rope performance. The observed sex- and weight-specific responses suggest the need for differentiated task progression in school-based interventions to maximize fitness benefits.
#7 Recycling emotions in football: effects of an emotional training program based on psychophysical metaphors with young footballers
Reference: Front Sports Act Living. 2026 Jun 2:8:1829114. doi: 10.3389/fspor.2026.1829114. eCollection 2026.
Authors: P Rivero-Mena, J Berastegui-Martínez, A F Rodríguez-Hernández
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13270670/pdf/fspor-08-1829114.pdf
Summary: This study examined the role of emotional intelligence (EI) in self-confidence, self-efficacy, and football-related capacities in youth players, and evaluated the effects of an emotional training program based on psychophysical metaphors. A pre-experimental one-group pretest-posttest design was conducted with 70 youth football players. Self-reported and hetero-reported EI, self-confidence, self-efficacy, and football-related capacities were assessed before and after a 4-month emotional training intervention. EI dimensions showed differential associations with psychological and football variables. Changes associated with the intervention were observed in self-confidence, hetero-reported emotional competencies, and several football-related capacities, with large effect sizes, although self-efficacy did not significantly improve. Given the pre-experimental design, causal attribution cannot be established. Findings highlight the complex and non-linear role of EI in football performance and support the effectiveness of an emotional change-based intervention, offering an innovative alternative to traditional psychological training approaches in developmental football contexts.
#8 Co-Creation of an Injury Prevention Implementation Strategy for a Girls‘ Football Team in a Community-Based Club
Reference: Scand J Med Sci Sports. 2026 Jun;36(6):e70313. doi: 10.1111/sms.70313.
Authors: Christian Victor Otte Odgaard, Kristine Sørensen, Carsten Møller Mølgaard
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13276011/pdf/SMS-36-e70313.pdf
Summary: The aim of this study was to investigate (1) Football coaches‘ and players‘ experiences with a co-created injury prevention (IP) implementation strategy, (2) Football coaches‘ and players‘ visions for improving the implementation of IP; and (3) to which extent the initial co-created implementation strategy increases the use of IP exercises. A mixed-method design consisting of observations and interviews. An implementation strategy was co-created with five youth girls‘ coaches in a community-based football club. The process was evaluated through semi-structured focus group interviews with five coaches and eight youth players. Observations of football sessions were conducted before intervention, 5 weeks after and 7 months after implementation. Interviews were analyzed using reflexive thematic analysis. Five themes were generated from the coaches‘ interview: (1) use of IP during intervention period, (2) challenges during intervention period, (3) positive experiences during the intervention, (4) responsibility and other stakeholders, and (5) visions for future implementation. Four themes were generated from interviewing the players: (1) experiences with IP during the intervention, (2) injuries and consequences, (3) motivation, and (4) visions for implementation. Observations showed increased duration of IP and increased number of IP exercises after 5 weeks, but limited changes after 7 months. The co-created strategy led to a limited increase of IP exercises used. While coaches had mixed experiences with IP during the intervention, the players generally had positive experiences. The participants‘ visions for improving the implementation were to engage multiple stakeholders, change the culture of the club, and gain knowledge.
#9 Links between concussion history, hypertension, and hypertension contributing factors among adolescent football athletes
Reference: Phys Sportsmed. 2026 Jun 17. doi: 10.1080/00913847.2026.2691686. Online ahead of print.
Authors: Jihyun Oh, Jessica Wallace
Summary: Recent studies show that former professional football players have an increased mid-life risk of cardiovascular disease (CVD), including hypertension related to their prior concussion exposure while playing football. Adolescent football players at risk of concussion are exposed to biopsychosocial risk factors of CVD, and increase likelihood of stroke in adulthood. This study aims to examine the association between concussion history and hypertension among adolescent football athletes, adjusting for health-related anthropometric measures, post-concussion symptoms, and behavioral/environmental factors. Data were drawn from a prospective cohort study’s cross-sectional baseline with self-reported concussion history. A total of 390 adolescent football athletes (mean age = 15.8 ± 1.2 years) in secondary schools participated in the study. The primary exposure included concussion history (yes/no). Other independent variables included post-concussion symptom scale (PCSS) severity, subjective social status (SSS), sleep disturbance score, and anthropometric measures (waist circumference, BMI, body fat, obesity level). The main outcome variable was blood pressure in the hypertensive range, defined as a binary-coded variable (SBP ≥ 130 mmHg, DBP ≥ 80 mmHg). A multivariable logistic regression model was conducted with complete cases (n = 327). A total of 31.4% of individuals (n = 121) had blood pressure in the hypertensive range. The multivariable logistic regression analysis showed that body fat is significantly and positively associated with blood pressure in the hypertensive range (AOR = 1.06, p = 0.03). However, concussion history, PCSS severity, SSS, sleep disturbance, waist circumference, and obesity level were not significantly associated (all ps > 0.05). Body fat percentage was positively associated with blood pressure in the hypertensive range in this sample, whereas no association with concussion history was observed. The results suggest that risk factors noted in former professional football athletes may not strongly impact blood pressure in adolescence but could raise concerns for increased CVD risk as these athletes move through the lifespan.
#10 Influence of the relative age effect and maturity status on competitive playing time in an elite football academy
Reference: Front Sports Act Living. 2026 Jun 1:8:1815789. doi: 10.3389/fspor.2026.1815789. eCollection 2026.
Authors: Ignacio Díaz-Almazán, Diego Muriarte, Manuel Barba-Ruiz, Francisco Gallardo Mármol, Rodrigo García de la Chica, Adrián Martín-Castellanos
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13265563/pdf/fspor-08-1815789.pdf
Summary: The Relative Age Effect (RAE) could influence talent identification and playing opportunities in youth football. The aim of this study was to examine the influence of RAE and maturity status on competitive playing time in an elite football academy. A cross-sectional study was conducted looking at 172 cases of male youth football players (U12-U15). Although data were collected over two seasons (2023-2024 and 2024-2025), the analyses did not include between-season comparisons. Accumulated competitive minutes played across the season were analyzed using a linear mixed-effects model, and associations between the categorical variables were examined using the chi-square test. The findings showed that none of the primary effects were statistically significant. The results suggest a trend in the expected direction; however, the effect was not statistically significant for status, (p = .057), and quartile, (p =.054). Late-maturing players were associated with a significant decrease in playing time (minutes) (p = .017). In contrast, being a defender (p = .035), and belonging to quartile 2 (p = .034) were linked to significant increases in playing time (minutes). There were more midfielders with late development (adjusted residual = 3.7), and more defenders with early development than expected by chance (adjusted residual = 1.98). These findings suggest that both RAE and maturity status influence playing opportunities in elite youth football, highlighting the need for development-oriented competition structures.
#11 Development of a psychological risk indicator and its association with sports injuries in football players
Reference: Sci Rep. 2026 Jun 16. doi: 10.1038/s41598-026-55958-z. Online ahead of print.
Authors: Eduardo Morelló, Verónica Gómez-Espejo, Laura Gil-Caselles, Alejandro García-Mas, Jon Larruskain, Aurelio Olmedilla-Zafra
Download link: https://www.nature.com/articles/s41598-026-55958-z_reference.pdf
Summary: Evidence suggests that psychological factors such as stress, anxiety, perfectionism, coping resources, and sleep quality may modulate sport-injury risk, supporting an integrative approach to athlete monitoring beyond physiological indicators. This study aimed to develop a composite psychological injury-risk index grounded in the Psycholight framework and examine its association with injury burden in male and female football players. A total of 281 youth-to-senior players aged 16-32 years completed validated self-report measures assessing sport-related psychological characteristics, maladaptive perfectionism, trait anxiety, emotional symptoms, and sleep quality, including the CPRD, MPSI, STAI-Trait, DASS-21, and PSQI. Baseline assessments were completed at the start of the season, while emotional symptoms and sleep quality were monitored monthly. Time-loss injuries were recorded throughout the season by the club’s medical staff using standardized procedures. Analyses included descriptive statistics, between-group comparisons, and Poisson generalized linear mixed models. Overall, higher composite risk-index scores were associated with higher injury rates across follow-up periods. In male players, high-risk scores in stress control were associated with higher injury incidence than low- and moderate-risk scores. In female players, higher depressive symptom scores and higher global risk-index scores were associated with higher injury incidence; additionally, moderate-risk scores in evaluation influence were linked to increased injury incidence. These findings support the potential utility of a composite psychological risk index for identifying players with heightened psychological vulnerability and highlight the potential value of incorporating systematic psychological screening into injury-prevention programmes in high-performance football.
#12 Transcranial Photobiomodulation Promotes Neurological Resilience in Current Collegiate American Football Players Exposed to Repetitive Head Acceleration Events
Reference: J Neurotrauma. 2026 Jun;43(11-12):850-871. doi: 10.1177/08977151251403554. Epub 2026 Jan 20.
Authors: Hannah M Lindsey, Carrie Esopenko, Divya Jain et al.
Summary: Repetitive head acceleration events (RHAE) are common in contact sports and associated with neuroinflammation, axonal injury, and long-term neurological impairments, including increased risk for chronic traumatic encephalopathy. Current strategies for addressing RHAE focus on post-injury care rather than proactive neuroprotection, leaving athletes vulnerable to cumulative neurotrauma. Transcranial photobiomodulation (PBM) has shown promise in reducing neuroinflammation and promoting neuroprotection in traumatic brain injury; however, its potential to mitigate the structural brain changes associated with RHAE in actively competing athletes has not been investigated. The aim of this study was to investigate whether PBM mitigates RHAE-related neuroinflammatory and microstructural changes in collegiate American football players over a single National Collegiate Athletic Association Division I season. We hypothesized that restricted diffusion imaging (RDI) and quantitative anisotropy (QA), diffusion magnetic resonance imaging markers of neuroinflammation and axonal remodeling, respectively, would increase in the Sham PBM group due to RHAE exposure but remain stable in the Active PBM group, indicating neurological resilience. Twenty-six collegiate football players were randomly assigned to Active (n = 13) or Sham (n = 13) PBM groups. PBM (810 nm) was self-administered 3 days a week under supervision in the athletic training room with a transcranial plus intranasal device throughout the preseason practice period and regular season (16 weeks). Diffusion MRI data were collected pre- and postseason, and correlational tractography was used to assess the effects of PBM on longitudinal changes in RDI and QA. Moderation analyses examined time × group interactions, with post hoc analyses exploring within- and between-group differences in RDI and QA cross-sectionally and longitudinally. Correlational tractography revealed significant main effects and interactions of time and group, with widespread increases in RDI and QA observed in the Sham PBM group over the season, consistent with neuroinflammation and axonal remodeling. In contrast, the Active PBM group showed relative stability in RDI and QA over time, with significant reductions observed in some areas. These findings suggest that PBM may mitigate ongoing neuroinflammation and facilitate the recovery processes. This study provides the first evidence suggesting that transcranial PBM reduces neuroinflammatory and axonal injury markers in American collegiate football players over a single season. PBM may serve as a noninvasive and accessible intervention for mitigating the cumulative neurological effects of RHAE exposure, offering a neuroprotective strategy for athletes participating in collision and contact sports. Future research should examine the long-term benefits of PBM across multiple seasons and its impact on functional outcomes to further establish the role of PBM in athlete brain health and wellness.
#13 The effects of menstrual cycle phase on jumping performance in women’s football players: a systematic review
Reference: Front Sports Act Living. 2026 May 29:8:1789611. doi: 10.3389/fspor.2026.1789611. eCollection 2026.
Authors: Catarina Marques, Miguel Rebelo, João Serrano, Hélder Fonseca
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13260357/pdf/fspor-08-1789611.pdf
Summary: This systematic review aimed to evaluate the available evidence on the influence of menstrual cycle (MC) phases on vertical jump performance (countermovement jump and squat jump height) in female football players. The review was conducted in accordance with PRISMA guidelines and registered in PROSPERO (ID1035357). A systematic search was performed in PubMed, Scopus, and SPORTDiscus (EBSCO). Studies were included if they involved female football players, assessed vertical jump performance, and compared performance across MC phases. Methodological quality was assessed using a modified Downs & Black checklist for non-interventional studies. Seven studies met the inclusion criteria. Substantial heterogeneity was observed regarding MC phase determination procedures, sample characteristics, and testing protocols. Although some studies reported higher vertical jump height values during the follicular or ovulatory phases, no statistically significant differences were found. Current evidence is insufficient to determine whether MC phases influence vertical jump performance in female football players. Findings should be interpreted cautiously due to methodological limitations in MC phase determination and low statistical power. Future research should aim to standardize protocols, use objective hormonal verification, and recruit larger samples.
#14 Changes in balance performance and Its determining factors in the lower leg during the competition season in adolescent football players
Reference: Front Sports Act Living. 2026 May 28:8:1769946. doi: 10.3389/fspor.2026.1769946. eCollection 2026.
Authors: Inese Pontaga, Agris Liepa, Valters Abolins, Andrew Rinaldi Sinulingga, Kristaps Slaidins
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13253643/
Summary: The aim of our study was to evaluate changes in static and dynamic balance, shin muscle strength, active and passive ankle range of movement (ROM), and foot kinesthetic acuity during the first 8 weeks of the competitive season in male adolescent football players. Thirteen players (age 15.26 ± 0.93 years, Tanner stages 3-4) participated. Static and dynamic single-leg balance and foot kinesthetic sense were assessed using a stabilometric platform. Ankle plantarflexion-dorsiflexion and inversion-eversion ROM were measured with a goniometer. Peak isometric force of the ankle plantar flexors, dorsiflexors, invertors, and evertors was measured with a handheld dynamometer, and peak torque was calculated as force × lever arm length. Eight weeks of competitive period was associated with static balance improvement: mean anterior-posterior and medial-lateral sway speeds decreased bilaterally (P = 0.024). Center of pressure (CoP) perimeter decreased significantly in the non-dominant (N) leg (P = 0.028). CoP perimeter and sway speed were positively correlated with passive dorsiflexion/plantarflexion ROM, and CoP ellipse area was correlated with active plantarflexion ROM (P ≤ 0.049). Dynamic balance improvement: the trunk total standard deviation (TTD) angle decreased when standing on the dominant (D) and N legs (P ≤ 0.018). TTD angle was negatively correlated with peak ankle dorsiflexion, eversion, and inversion torques (P ≤ 0.039). Passive plantarflexion ROM decreased bilaterally (P ≤ 0.04), whereas active ROM remained unchanged (P ≥ 0.05). Absolute and relative peak isometric dorsiflexion torques increased bilaterally (P ≤ 0.003), but side asymmetry (higher plantar- and dorsiflexion torques in the D leg) persisted (P ≤ 0.045). Mean kinesthetic sense error was lower with the D leg, whereas trial completion time was shorter with the N leg in both sessions (P ≤ 0.032).
#15 A graph-integrated reinforcement learning framework with graph neural networks for tactical decision modeling in professional football
Reference: Sci Rep. 2026 Jun 13. doi: 10.1038/s41598-026-50061-9. Online ahead of print.
Authors: Jiqian Lin, Fang Chen, Jia Liu
Download link: https://www.nature.com/articles/s41598-026-50061-9_reference.pdf
Summary: The increasing availability of high-frequency player tracking and event data has enabled more detailed analysis of football tactics, yet many existing approaches struggle to connect learned decisions with realistic execution constraints and interpretable tactical reasoning. This study proposes a graph-integrated reinforcement learning framework with graph neural networks (GIRL-GNN) for offline tactical decision modeling in professional football. Each decision moment is represented as a heterogeneous graph constructed from synchronized tracking and event data, encoding player interactions, ball movement, spatial context, and match state. A hierarchical policy separates high-level tactical intent from low-level executable control, while an explicit feasibility module evaluates candidate actions with respect to timing, visibility, defensive pressure, and rule constraints. Learning combines calibrated predictions of value gain, defensive risk, and execution feasibility under a risk-sensitive objective. The framework is evaluated on seven professional matches using a leave-one-match-out protocol. Results indicate consistent improvements over sequence-based and rule-based baselines across multiple tactical dimensions, including offensive progression, defensive suppression, feasibility, and robustness under input noise within the evaluated dataset. Calibration analysis indicates reliable alignment between predicted and observed outcomes, and qualitative analyses show that the learned policies reflect recognizable tactical structures consistent with professional performance indicators. These findings suggest that feasibility-aware, graph-based reinforcement learning provides a promising direction for data-driven tactical decision analysis within the scope of the evaluated dataset.
#16 The organisation of medical and performance departments in European elite football teams
Reference: Sci Med Footb. 2026 Jun 13:1-12. doi: 10.1080/24733938.2026.2685134. Online ahead of print.
Authors: Benedict Gondwe, Monika Frenger, Tim Meyer
Summary: Elite football clubs rely heavily on medical and performance units to optimise players‘ health care and performance. Despite their growing importance, little is known about how these departments are structured and managed. This study investigates the organisational structure and operational processes within medical and performance departments in elite European football clubs. An online survey was distributed to 193 professional football clubs in 29 European countries, with 66 complete responses (34% response rate). Descriptive quantitative analyses and descriptive analyses of open-ended items explored leadership models, communication, data management, and return-to-play (RTP) procedures. Organisational structures varied, with flat (30%), functional (21%), and matrix (23%) models most common. Regional differences in leadership configurations were observed, though not statistically significant between European regions. Most departments reported to a Sports Director (42%) and operated with established communication pathways, with 89% agreeing that information was effectively transferred. Data were primarily stored centrally within the medical department or the club. Return-to-play practices almost exclusively followed a phased model, with physiotherapists central across all stages. Team doctors were heavily involved in early stages but less so during return to performance, where sport scientists and rehab coaches became more prominent reflecting current multidisciplinary RTP frameworks. High levels of external engagement (91%) and research involvement (62%) highlight a growing emphasis on evidence-based practice. These findings describe substantial structural heterogeneity and increasing professionalisation of medical and performance departments in European elite football. Regional variability and differences in leadership, data management, and decision-making processes warrant further investigation rather than direct comparison.
#17 Visualizing heterogeneous associations: economic capital and adolescent football participation in China: a cross-sectional study using quantile regression with school-level fixed effects
Reference: Front Psychol. 2026 May 29:17:1798818. doi: 10.3389/fpsyg.2026.1798818. eCollection 2026.
Authors: Donghui Jin, Zhengri Quan, Dan Pang, Nanhu Li
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13260315/pdf/fpsyg-17-1798818.pdf
Summary: Fair participation in sports is a key focus of public health, but socioeconomic barriers limit youth participation. Although family wealth is related to participation, its specific differences at different levels of opportunity are not yet clear. This study goes beyond the average correlation and deeply analyzes the differentiated relationship between adolescent family economic capital and opportunities for football participation. We conducted a cross-sectional survey among 1,860 adolescents aged 12-18 years (from 42 schools) in Jilin Province. The sample was selected by multi-stage stratified cluster sampling. Data were collected using a standardized questionnaire. The study constructs a comprehensive „Football Participation Opportunity Index“ and „Family Economic Capital Index.“ After controlling for a range of personal, family, and environmental factors, we estimated the coefficients of economic capital at the 10th, 25th, 50th, 75th, and 90th quantiles of the FOI distribution using quantile regression models with school fixed effects. At the same time, we have drawn a series of charts to visualize the data base, methodological principles, core findings, potential mechanisms and policy implications. The analysis revealed a significant J-type association pattern. The impact of economic capital was strongest in the group with the lowest chance of participation (10th quantile; β = 0.341, 95% CI: 0.250-0.432), suggesting that it may constitute a critical participation threshold. The effect weakened around the median but strengthened again at the top of the chance distribution (90th quantile; β = 0.260, 95% CI: 0.145-0.375), suggesting that it may be related to access to elite-level opportunities. Visualization analysis further illustrates that other factors, such as urban household registration, parental contacts and school facilities, also show different patterns of association throughout the opportunity spectrum. The correlation between family economic capital and youth football participation shows a significant random level change, revealing inequality at both ends. We need to adopt a dual track strategy: providing economic support for disadvantaged youth, while ensuring transparency and merit based selection in elite selection. The visualization framework enhances the understanding and conversion potential of discoveries.
#18 Sleep quality and injury risk in adolescent football players: an amplified effect for high-risk athletes revealed by quantile regression
Reference: Front Public Health. 2026 May 28:14:1799229. doi: 10.3389/fpubh.2026.1799229. eCollection 2026.
Authors: Nanhu Li, Zhengri Quan, Dan Pang, Donghui Jin
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13253420/pdf/fpubh-14-1799229.pdf
Summary: Sleep quality is a key regulatory factor in sports injury, but it is not clear whether its association with injury risk is homogeneous or varies among athletes with different baseline risks. This study explored the heterogeneous and non-linear associations between sleep quality and risk of impairment. We conducted a cross-sectional analysis of 478 young football players from 12 Chinese clubs. Sample size was determined based on the need to provide stable estimates across multiple conditional quantiles, exceeding the general rule of thumb for complex multivariate models. Sleep quality was assessed using the Pittsburgh Sleep Quality Index while recording its subcomponents, such as sleep duration. Injuries, including time lost and severity, were recorded during the past season. Using quantile regression, we analyzed the association between total PSQI score and the number of impairments across the conditional distribution (τ = 0.25, 0.50, 0.75, 0.90) after controlling for team-level fixed effects and covariates. We observed a strong positive correlation between the PSQI score and the incidence of injury. Quantile regression revealed significant heterogeneity: this adverse association was greatly amplified at higher quantiles of injury risk. The PSQI coefficient increased from 0.07 (95% confidence interval: 0.01, 0.13) in the 25th quantile to 0.33 (95% confidence interval: 0.23, 0.43) in the 90th quantile, indicating that the strength of the association was enhanced about fivefold for high-risk athletes. Separate analysis for severe injuries corroborated this finding. A nonlinear J-type dose-response relationship was also identified, with the risk accelerating when the PSQI score exceeded 6. The association between poor sleep and injury risk was not uniform but showed a clear gradient, with the most significant adverse associations concentrated in high-risk athletes. This quantile-dependent effect highlights the potential of sleep intervention as a precision strategy. While sleep quality remains important for all adolescent football players, targeted sleep health promotion for high-risk individuals can maximize the injury prevention benefits of adolescent athletes, but prospective studies are still needed to establish causality.
#19 Effects of Caffeinated Chewing Gum on Psychophysiological Responses and Kinematic Profiles During Intermittent and Continuous Small-Sided Soccer Games in Young Male Players: A Randomized Crossover Trial
Reference: Nutrients. 2026 Jun 18;18(12):1962. doi: 10.3390/nu18121962.
Authors: Bulent Kilit, Ersan Arslan, Yusuf Soylu
Summary: Caffeinated chewing gum is a practical, rapidly absorbed ergogenic aid increasingly used in team sports, yet its interaction with different small-sided soccer game (SSG) formats in young male players remains unclear. This study evaluated the effects of acute caffeinated (CAF) chewing gum on psychophysiological responses and kinematic profiles during intermittent (INT) and continuous (CON) 3-a-side SSGs. Twenty-four young male soccer players (18.4 ± 0.5 years) completed four 3-a-side SSG sessions separated by 48 h in a randomized, double-blind, placebo (PLA)-controlled, crossover design (CAF-INT, PLA-INT, CAF-CON, PLA-CON). Participants chewed 300 mg of CAF or PLA gum for 5 min, with mastication completed 5 min before warm-up session. The heart rates and kinematic profiles were recorded during the SSGs, and the ratings of perceived exertion (RPE), exercise enjoyment scale (EES), and visual analogue scale (VAS) to perceived mental fatigue (MF) were assessed post-game. Compared with the PLA, the CAF increased the heart rate responses (HR), EES, total distance (TD), player load (PL), acceleration (ACC), and distances covered in selected speed zones (from Z0 to Z5), while reducing the RPE and MF. Significant format × supplementation interactions indicated that CAF-induced changes in high-intensity kinematic outcomes (TD, PL, ACC, Z2-Z5) and HR responses (HRmean, HRmax) were generally greater in INT, whereas CAF-induced increases in low-intensity running distances (Z0 and Z1) and %HRmax were more pronounced in the CON format (all p < 0.05 for the reported effects; ηp2 = 0.16-0.93 for CAF main effects [large effects]). The EES improvements were more pronounced in the CON format, whereas the MF and RPE reductions were more pronounced in the INT format. CAF chewing gum may be a practical acute strategy for modulating psychophysiological responses and kinematic profiles during SSGs, with the effects depending partly on the game format.
#20 Multimodal Functional Assessment of Asymmetries in Youth Soccer Players: Study Protocol
Reference: Life (Basel). 2026 May 24;16(6):876. doi: 10.3390/life16060876.
Authors: Ada-Maria Codreanu, Dan-Andrei Korodi, Nicoleta-Alexandra Lupu et al.
Download link: https://www.mdpi.com/2075-1729/16/6/876
Summary: Youth soccer players are exposed to repeated unilateral loading during a period of rapid growth and neuromuscular maturation. These demands may contribute to postural deviations and inter-limb functional asymmetries that can influence movement control and mechanical efficiency. This study protocol aims to establish a standardized multimodal framework for assessing postural alignment, postural control, lower limb mechanical output, ankle dorsiflexion strength, support-limb neuromuscular activation, and contextual training and recovery variables in licensed youth soccer players aged 13 to 17 years. This prospective observational study will include 75 male youth soccer players recruited from S.C. Fotbal Club Ripensia Timișoara S.A. The primary outcome is the inter-limb asymmetry index derived from unilateral countermovement jump performance. Secondary outcomes include postural alignment, balance, bilateral jump performance, ankle dorsiflexion strength, and support limb electromyographic activity during the instep kick. Participants will complete a clinical evaluation questionnaire, including demographic, training, and recovery variables. Assessments will be conducted using the GaitON system, Kinvent K-Delta force platforms, K-Myo surface electromyography, and K-Pull dynamometry, before and after a regular training session. Biological maturation will be estimated using the Mirwald maturity offset method. The protocol will allow characterization of inter-limb asymmetries across postural, balance, jump, and electromyographic parameters.
#21 Hormonal Adaptations in Professional Soccer Players: Ethnic Differences and Pathophysiological Mechanisms
Reference: Int J Mol Sci. 2026 Jun 20;27(12):5574. doi: 10.3390/ijms27125574.
Authors: Sandro La Vignera, Rosita A Condorelli
Summary: Professional soccer imposes substantial physiological demands eliciting complex neuroendocrine responses. This review synthesizes evidence on hormonal adaptations in professional soccer players, with emphasis on ethnic and national differences and underlying pathophysiological mechanisms. We analyzed 21 key studies investigating testosterone, cortisol, the testosterone-to-cortisol (T:C) ratio, growth hormone (GH), and insulin-like growth factor-1 (IGF-1) responses to training and competition. Acute cortisol elevations that may persist for up to 72 h post-match in some professional populations and T:C ratio reductions following congested fixture periods are reported across available studies, while somatotropic responses vary considerably across studies. Preliminary evidence suggests that ethnic and geographic background may influence circulating testosterone and urinary steroid excretion profiles, with UGT2B17 genetic polymorphisms identified as one contributing factor; however, the evidence base is limited and requires replication. Approximately 7.4% of elite junior cohorts-though not necessarily professional adult populations-develop non-functional overreaching (NFOR), characterized by blunted GH and ACTH responses. Pathophysiological mechanisms involve hypothalamic-pituitary–adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axis dysregulation producing anabolic-catabolic imbalance. Individualized, longitudinal T:C monitoring and post-match load moderation may be warranted; future research should establish ethnicity-specific normative values and investigate links between hormonal dysregulation and injury risk.
#22 Perceptual Decision Efficiency and Optimal Sleep Quality Are Associated with Female College Soccer Injury Avoidance
Reference: Brain Sci. 2026 Jun 11;16(6):624. doi: 10.3390/brainsci16060624.
Authors: Gary B Wilkerson, Marisa A Colston, Madison R Ekas et al.
Summary: Sport-related injuries are common, and often recurrent, among female college soccer players. This exploratory cohort study investigated whether perceptual decision efficiency and sleep quality could discriminate between injured and uninjured players. Twenty-seven NCAA Division I women’s soccer players (19.5 ± 1.3 years) completed a perceptual response training program, administered through an immersive virtual reality system, across a 13-week season. Players completed 11 training sessions progressing through four levels of task difficulty, with conjugate eye movements, neck rotation, and whole-body lunge-reach responses measured for each trial. Four metrics, elapsed time, rate correct per second, across-trials variability, and an efficiency index, were calculated for each of three defined time segments: perceptual decision, action initiation, and perceptual-motor response. The Pittsburgh Sleep Quality Index (PSQI) and Global Well-Being Index (GWBI) were administered prior to the first practice session, and all subsequent time-loss injuries were documented. Receiver operating characteristic analyses, Kaplan-Meier survival analysis, and classification tree modeling were used to evaluate injury discrimination. Twelve time-loss injuries, including five concussions and seven lower extremity musculoskeletal injuries, were sustained by 10 of the 27 players. Optimal discrimination between injured and uninjured players was derived from the perceptual decision efficiency (PDE) metric for the most difficult perceptual response training task (AUC = 0.682-0.794), with a binary cut point of ≤6.02 yielding an odds ratio of 5.60 (95% CI: 1.02, 30.90; Mantel-Cox log rank p = 0.025). All five concussions occurred in players classified as high-risk by a suboptimal PDE value. Pre-participation PSQI demonstrated an AUC of 0.735. Notably, no player with both an optimal PDE value and a favorable sleep quality score (PSQI < 4) sustained a time-loss injury. Moderate-to-large training-related improvements in perceptual decision metrics were observed for the least challenging task from early- to late-season sessions. Optimal values for PDE and sleep quality together characterized female college soccer players who avoided injury. Both factors appear to be modifiable, suggesting that perceptual response training combined with interventions to enhance sleep quality may enhance injury resistance. Independent validation in larger, diverse athlete cohorts is warranted.
#23 The Effects of Match-Play on Markers of Recovery in Professional Female and Male Soccer Players
Reference: J Strength Cond Res. 2026 Jun 23. doi: 10.1519/JSC.0000000000005586. Online ahead of print.
Authors: Will Abbott, Samantha N Rowland, Chloe E McKnight, Emily J Hansell, Tom Clifford
Summary: We examined the effects of match-play on muscle soreness and neuromuscular performance metrics in female and male soccer players. Nine professional female players (age, 24 ± 3 years; height, 1.76 ± 0.06 m; mass, 72.1 ± 6.7 kg) from the Women’s Super League 2, and 13 professional male players (age, 19 ± 1 year; height, 1.81 ± 0.06 m; mass, 79.6 ± 7.2 kg) from the same club in the U21 Professional Development League 2 in England participated. To assess neuromuscular performance, players completed countermovement jumps (CMJ), the isometric hamstring 90/90 strength test, and isometric hip adduction tests on both legs, before match day (MD; Pre) and 2 (MD+2) and 3 days (MD+3) postmatch. Surveys to measure muscle soreness, and menstrual cycle-related symptoms for female players, were completed on MD and on MD+1, MD+2, and MD+3. In female players, muscle soreness was elevated, and all neuromuscular performance indices were significantly reduced at MD+3 (p < 0.05). Conversely, in male players, muscle soreness was greater at MD+1 (p = 0.027) but none of the neuromuscular markers were lower than prematch levels by MD+3 (p > 0.05). Muscle soreness and all neuromuscular indices were significantly more affected in female vs. male players (all p < 0.05). At MD+3, in female players, CMJ height was ∼7% below Pre, whereas it was ∼1% higher in male players. Menstrual cycle symptoms were modest but when added as covariates to mixed models, were negatively associated with right adductor strength (p = 0.001) but no other metrics. Female players may recover slower than male players after soccer matches as muscle soreness and markers of neuromuscular performance were significantly more impaired in the female players 3 days postmatch.