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 Physical Factors Associated With Stage Progression of Lumbar Spondylolysis: A Prospective Cohort Study in Male Adolescent Soccer Players

Reference: Orthop J Sports Med. 2026 Jan 15;14(1):23259671251401599. doi: 10.1177/23259671251401599. eCollection 2026 Jan.
Authors: Toshiharu Tsutsui, Wataru Sakamaki, Seira Takei, Nodoka Ikegami, Suguru Torii
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12808583/pdf/10.1177_23259671251401599.pdf
Summary: Lumbar spondylolysis (LS) has distinct pathologic stages, and worsening LS can cause poor bone union and low back pain. However, the risk factors involved in LS pathogenesis remain unclear. The purpose was to identify risk factors associated with the pathologic progression of LS at the L5 in adolescent male soccer players. A total of 189 male adolescent soccer players aged 12 to 14 years were recruited. We used lumbar magnetic resonance imaging (MRI) to examine adolescent soccer players‘ lumbar lordosis (LL), sacral slope (SS), sacral rotation angle, maturity stage of the lumbar vertebral bodies, and bone marrow edema (BMO) at L5. In addition, whole-body dual-energy x-ray scans measured bone mineral density and content as well as trunk lean body mass. Moreover, we tested the flexibility of the iliopsoas, hamstrings, and quadriceps, as well as evaluated the range of motion (ROM) of the hip in both external and internal rotation. LS stages were determined using computed tomography (CT)-like and short-tau inversion recovery (STIR) modes. The change over the 6-month period was the main outcome; participants were classified as „worsened,““improved,“ or „no change.“ The worsened group was defined by a pathological progression on CT-like mode or new BMO appearance on STIR mode without CT-like change. Multiple logistic regression analysis was then performed to identify risk factors for the pathologic progression of LS. Of the 163 players analyzed, 47 (28.5%) showed LS progression. BMO (odds ratio [OR], 5.54; 95% CI, 2.23-13.76), SS relative to LL (OR, 5.58; 95% CI, 2.32-13.51), sacral rotation angle ≤-1.5 or ≥1.5 (OR, 5.74; 95% CI, 2.36-13.96), and hip external rotation ROM (OR, 4.30; 95% CI, 1.67-11.06) were significantly associated with the pathologic progression of LS. Our study demonstrated that the risk factors for LS progression in male adolescent soccer players include BMO, sacral anteversion relative to LL, sacral rotation, and restricted hip external rotation ROM. Early BMO detection and sacral malalignment improvement may prevent pathologic LS progression in male adolescent soccer players.

2 ‚Match load‘ construct in professional football: complexities and considerations

Reference: BMJ Open Sport Exerc Med. 2026 Jan 20;12(1):e002894. doi: 10.1136/bmjsem-2025-002894. eCollection 2026.
Authors: Ben Dixon, Jill Alexander, Damian Harper
Download link: https://bmjopensem.bmj.com/content/bmjosem/12/1/e002894.full.pdf
Summary: The differentiation between training load and match load is an important consideration in applied practice, with the match load construct being used in athlete monitoring to inform training prescription and return to play decision-making post-rehabilitation. The term ‚match load‘ lacks a clear definition, and its complexity requires greater recognition. We propose a practical, conceptual framework for match load and influential contextual factors to consider within professional football that may impact a player’s match load. The aim of the article is to provide practitioners with definitions of match load categories and to guide future research that may help enhance the measurement and management of load to inform training and rehabilitation processes.

3 The impact of time-restricted feeding on energy and macronutrient intake among elite Jordanian football players: a randomized controlled trial

Reference: Front Sports Act Living. 2026 Jan 7:7:1657828. doi: 10.3389/fspor.2025.1657828. eCollection 2025.
Authors: Hadeel Ghazzawi, Razan Mahmoud Omoush, Rand Iblasi, Adam Amawi
Download link: https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2025.1657828/full
Summary: Nutrition is a key factor in optimizing training, performance, recovery, and health among athletes. Intermittent fasting (IF) is one of the nutritional strategies. To compare the effect of an 8-week time-restricted feeding (TRF) protocol vs. a standard diet on energy and macronutrient intake among professional football players. A randomized controlled trial was conducted among 30 professional adult male football players, a 16/8 time-restricted feeding (TRF) group vs. a control group. Dietary intake was assessed pre- and post-intervention (12 weeks) using a 7-day food record. Data were analyzed for energy and nutrient intake using ESHA Food Processor® software. At baseline, both groups consumed less energy and carbohydrates than recommended for elite athletes. Following the 8-week intervention, total energy and macronutrient intakes increased slightly in both groups, but changes were not statistically significant for energy or carbohydrates. The TRF group increased mean energy intake from 33 ± 8.0 to 36 ± 4.9 kcal/kg/day and carbohydrate intake from 4.02 ± 1.48 to 4.27 ± 0.82 g/kg/day, while the Control group increased from 38 ± 12.2 to 42 ± 11.0 kcal/kg/day and from 4.58 ± 2.11 to 5.13 ± 1.73 g/kg/day, respectively. Protein intake significantly decreased within the TRF group (from 2.21 ± 0.60 to 1.84 ± 0.51 g/kg/day, p = 0.01), while the Control group showed no significant change. Fat intake increased in both groups but without significant between-group differences. Despite modest improvements, both groups continued to fall below recommended energy and carbohydrate targets, and vitamins D and K remained markedly insufficient post-intervention. TRF did not significantly improve energy or macronutrient intake compared to the standard diet. Both groups exhibited persistent energy and carbohydrate deficits and inadequate vitamin D and K intake, highlighting the need for structured nutrition support regardless of feeding pattern.

4 Mind the Game: Virtual Reality-Based Cognitive Training to Enhance Decision-Making in Football Athletes

Reference: Cyberpsychol Behav Soc Netw. 2026 Jan 22:21522715261418826. doi: 10.1177/21522715261418826. Online ahead of print.
Authors: Francesca Celestina Rosanna Gala, Michele Trapletti, Giuseppe Riva, Claudia Repetto
Download link: https://journals.sagepub.com/doi/epub/10.1177/21522715261418826

5 Correlation between visual system function and visuo-cognitive skills in elite football players

Reference: Clin Exp Optom. 2026 Jan 22:1-11. doi: 10.1080/08164622.2025.2610974. Online ahead of print.
Authors: Jorge Jorge, João Pedro Jorge, Sandra Medrano Muñoz, António Dias
Summary: Understanding the link between visual system parameters and visuo-cognitive abilities can enhance strategies to optimise visual performance in daily and professional tasks. To investigate the relationship between visual system parameters – such as visual acuity, refractive error, binocular vision (including phoria, fusional vergences, vergence and accommodation facility, and stereopsis) – and visuo-cognitive abilities, including perception span, multiple object tracking, and visual reaction time. All measurements were conducted by the same specialist in a single session, starting with visual acuity assessment, followed by refractive error evaluation, binocular vision assessments, including phoria (cover test and Thorington test), fusional vergence, vergence facility, accommodative facility, and stereopsis, and concluding with visuo-cognitive tests, namely perception span, multiple object tracking, and reaction time. Data were analysed using Pearson’s correlation test, with a statistical significance set at p < 0.05. The study involved 218 elite male football players with a mean age of 24.6 ± 4.8 years. The perception span correlated positively with monocular (r = 0.185, p = 0.003) and binocular (r = 0.176, p = 0.005) visual acuity and negatively with anisometropia (r = -0.115, p = 0.045), near esophoria (r = -0.347, p = 0.010), and near stereopsis (r = -0.178, p = 0.004). Weak positive correlations were observed with positive fusional vergence at distance (r = 0.126, p = 0.032) and multiple object tracking (r = 0.207, p = 0.001). Multiple object tracking correlated negatively with horizontal phoria at both distance (r = -0.141, p = 0.019) and near (r = -0.141, p = 0.019) and with stereopsis at distance (r = -0.255, p = 0.024) and near (r = -0.142, p = 0.018), with more pronounced correlations in participants with esophoria. Visual reaction time correlated positively with emmetropia (r = 0.141, p = 0.019), distance horizontal phoria (r = 0.121, p = 0.037), and distance negative fusional vergence break (r = 0.124, p = 0.034). Binocular vision, vergence, and phoria may influence visuo-cognitive performance in elite football players. Effective binocular coordination and minimal refractive error appear beneficial, whereas esophoria was linked to reduced performance. Although correlations were weak, the findings highlight the multifactorial nature of visuo-cognitive function in sport.

6 Association Between Self-Reported Hip Crepitus and Pain, Quality of Life, and Psychological Features in Football Players With Hip/Groin Pain: A 2-Year Longitudinal Study

Reference: J Sport Rehabil. 2026 Jan 12:1-8. doi: 10.1123/jsr.2025-0353. Online ahead of print.
Authors: Fernanda Serighelli, Kay M Crossley, Matthew G King, Mark J Scholes, Joanne L Kemp, Joshua J Heerey, FORCe Group, Danilo De Oliveira Silva
Summary: Hip crepitus creates negative emotions and beliefs, leading to adaptations in sports and daily life activities. People with hip/groin pain present psychological responses to pain, and hip crepitus severity may amplify those features. We aimed to explore associations between self-reported hip crepitus severity and pain, quality of life, and psychological features at baseline and 2-year follow-up in football players with hip/groin pain. We recruited 184 football players with hip/groin pain (20% females, mean age [SD] = 27.6 [0.4]). Self-reported crepitus severity was assessed using a single item of the International Hip Outcome Tool-33. Pain severity was assessed using a Numeric Pain Rating Scale describing average pain playing football and average pain in the last month. Quality of life was assessed using the Copenhagen Hip and Groin Outcome Score subscale. Psychological features included standardized measures of kinesiophobia and pain catastrophizing. We assessed associations between crepitus severity and these outcomes using linear regression. At baseline, greater (worse) hip crepitus severity was associated with worse average pain in the last month (β = -0.02), quality of life (β = 0.16), and kinesiophobia (β = -0.05). We found sex interactions for pain catastrophizing and average pain playing football, with stronger associations in females (β = -0.19 and β = -0.03) than males (β = -0.09 and β = -0.01). Hip crepitus severity at baseline was not associated with changes in pain, quality of life, or psychological features over 2 years. Worse hip crepitus severity was cross-sectionally associated with worse pain, quality of life, and psychosocial features in football players with hip/groin pain, but not with the progression of these outcomes over 2 years. Females had a stronger association between hip crepitus and pain catastrophizing and average pain playing football than males at baseline.

7 Optimizing learning and motor performance in highly trained youth football players: the role of time interval between synchronous and asynchronous sessions in a blended training model

Reference: Front Sports Act Living. 2026 Jan 6:7:1736195. doi: 10.3389/fspor.2025.1736195. eCollection 2025.
Authors: Aymen Haweni, Amayra Tannoubi, Maha Gasmi, Vasile Emil Ursu, Vlad Adrian Geantă
Download link: https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2025.1736195/full
Summary: Effective motor performance in sport depends on the dynamic interaction between cognitive and physiological systems. However, it remains unclear how the temporal spacing between training sessions influences this interaction. This study examined the effects of the Time Interval Between Synchronous and Asynchronous Sessions (TIBSAS) on motor control and working memory in highly trained youth football players. Fifty-seven adolescent athletes (12.1 ± 0.9 years) participated in a randomized crossover design involving three interval conditions between training sessions: (1) no delay, (2) 6-12 h delay, and (3) 12-24 h delay. Motor performance was evaluated using a 15 m ball-dribbling test, and cognitive performance was assessed using the Sternberg working memory task. Data were analyzed with one-way repeated-measures ANOVA with Bonferroni correction. TIBSAS had significant impacts on both motor and cognitive performance. The 12-24 h interval (COND 3) produced considerably quicker dribbling times (3.60 ± 0.16 s) in comparison to COND 1 (3.96 ± 0.21 s, p < 0.001) and COND 2 (4.07 ± 0.23 s, p < 0.001), exhibiting a substantial effect size (η 2 = 0.50). Cognitive performance exhibited analogous enhancements, with COND 3 indicating significantly quicker reaction times for both one-item (733.74 ± 13.08 ms vs. 777.15 ± 41.91 ms, p < 0.001) and three-item memory loads (982.00 ± 40.19 ms vs. 1,022.30 ± 33.10 ms, p = 0.005). There were no significant differences in the five-item memory load. An optimal spacing of 12-24 h between training sessions enhances both motor execution and cognitive processing, suggesting improved integration of perceptual and executive systems in young athletes. These findings highlight the importance of time-dependent consolidation mechanisms in sport performance and offer practical guidance for designing cognitively informed training schedules.

8 Static Stretching Acutely Reduces the Ergogenic Effects of Caffeine on Sprint Performance but Not Maximal Ball Velocity in Football Players

Reference: Eur J Sport Sci. 2026 Feb;26(2):e70064. doi: 10.1002/ejsc.70064.
Authors: Refik Çabuk, İzzet İslamoğlu, Onur Demirarar, Faruk Albay, Yıldırım Kayacan
Download link: https://onlinelibrary.wiley.com/doi/epdf/10.1002/ejsc.70064
Summary: This study aimed to investigate the independent and combined effects of caffeine and static stretching (SS) on maximal ball velocity and 30-m sprint performance. Sixteen male amateur football players performed 30-m sprint and an instep kicking ball velocity test under six conditions. The six conditions were control, SS only, placebo only, placebo combined with SS (PLA + SS), caffeine only, and caffeine combined with SS (CAF + SS). A repeated measures ANOVA revealed no significant main effect of condition on maximal ball velocity (F(5, 75) = 1.11, p = 0.36, η2 p = 0.069). In contrast, a significant main effect of condition was observed for 30-m sprint performance (F(5, 75) = 4.57, p = 0.001, η2 p = 0.23). Our findings showed that the SS condition resulted in similar sprint performance compared to all other conditions (p ≥ 0.093) except the caffeine condition (p = 0.009). In contrast, the caffeine condition led to faster sprint performance compared to all conditions (p ≤ 0.010) except CAF + SS (p = 0.184). Additionally, sprint performances in the SS and CAF + SS conditions were similar (p = 0.093). A large effect size (0.94) was observed between the control and CAF conditions, whereas a moderate effect size (0.54) was found when comparing caffeine and CAF + SS conditions. These findings indicate that caffeine intake enhances sprint performance; however, the CAF + SS combination appears to reduce this effect, making it less effective. Although SS does not directly impair sprint performance, it may have the potential to diminish the ergogenic effects of caffeine.

9 Relative age selection bias does not translate into a playing-time advantage: evidence from Italian Serie A football

Reference: Front Psychol. 2026 Jan 5:16:1733277. doi: 10.3389/fpsyg.2025.1733277. eCollection 2025.
Authors: Paolo Riccardo Brustio, Alexandru Nicolae Ungureanu, Luca Beratto, Damiano Li Volsi, Corrado Lupo
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12812947/pdf/fpsyg-16-1733277.pdf
Summary: The Relative Age Effects (RAEs) represent a bias in talent identification and selection processes, favouring athletes born earlier in the selection year. This study aimed to (i) quantify the prevalence and magnitude of the RAEs in Italian elite football (Serie A), considering age categories, playing positions, and team ranking, and (ii) examine whether RAEs are associated with selection- and participation-related outcomes (i.e., match appearances, total playing time, and consistency of match participation). Data from 789 Serie A players were analysed. Q1 players were overrepresented compared with Q4 players (OR=1.9 [1.5-2.6]). RAEs were more pronounced in younger players (OR=2.1 [1.4-3.2]) and more evident among goalkeepers (OR=4.4 [1.8-10.6]) followed by forwards (OR=2.0 [1.0-3.8]), midfielders (OR=1.9 [1.1-3.1]) and defenders (OR=1.6 [1.0-2.4]). Moreover, RAEs were stronger in lower-tier teams (OR=2.5 [1.4-4.5]) than in top-tier teams (OR=1.5 [0.8-2.7]). No differences were observed between quartiles in selection- and participation-related outcomes. RAEs persist in Serie A rosters but appear to operate primarily as a selection-level bias within talent development and squad selection, affecting which players reach and remain at the elite level, rather than influencing coaches‘ decisions regarding match participation once players are part of the professional environment.

10 From strain to strength through humor: resilience in professional football players

Reference: Front Psychol. 2026 Jan 5:16:1699013. doi: 10.3389/fpsyg.2025.1699013. eCollection 2025.
Authors: Aydın Pekel, Mehmet Behzat Turan, Vesile Şahiner Güler, Mujahid Iqbal, Osman Pepe, Abdullah Arısoy, İbrahim Dalbudak
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12813008/pdf/fpsyg-16-1699013.pdf
Summary: Athletes often face competitive stress, with resilience and coping humor as key resources to mitigate its negative impact on mental well-being and performance. This study aims to examine the relationships between psychological strain, resilience, and coping humor among professional Turkish football players, and to investigate the moderating role of humor-based coping in the link between strain and resilience. This cross-sectional study involved 466 professional Turkish football players (2024-2025 season). Data were collected via the APSQ, BRS, and CHS, and analyzed using SPSS v22, which included correlations, regressions, and moderation testing with the PROCESS Macro Model 1 (5,000 bootstraps). Additionally, the Jamovi 2.6.2.0 Package program was used. Psychological strain significantly predicted resilience, and coping humor showed a direct positive effect on resilience. Significantly, coping humor moderated the relationship between strain and resilience, such that the positive association was strongest at high levels of coping humor. Athletes with higher humor-based coping skills were likelier to transform psychological strain into resilience, while the effect was nonsignificant at low humor levels. The findings demonstrate that coping with humor strengthens athletes‘ resilience and amplifies the beneficial effects of psychological strain when interpreted as a challenge. Integrating humor-based interventions into psychological training programs may enhance football players‘ adaptive coping skills, resilience, and overall mental well-being.

11 Pólya urn model for analysis of football passes

Reference: Phys Rev E. 2025 Dec;112(6):L062303. doi: 10.1103/w5wk-mmcc.
Authors: Ken Yamamoto
Summary: This study analyzes pass networks in football (soccer) using a stochastic model known as the Pólya urn. By focusing on preferential selection, it theoretically demonstrates that the time evolution of networks can be characterized by a single parameter. Building on this result, a data analysis method is proposed and applied to a large-scale public dataset of professional football matches. The statistical properties of the preferential-selection parameter are examined, demonstrating its correlation with pass accuracy and with mean pass difficulty. This method is applicable to various evolving networks.

12 Interpersonal interactions improve the representativeness of embodied decision-making in football

Reference: Psychol Sport Exerc. 2026 Jan 16:103063. doi: 10.1016/j.psychsport.2026.103063. Online ahead of print.
Authors: Daniel Müller, Oliver Höner, Danique van der Veerdonk, Willem van der Meer, David Mann
Summary: Decision-making is a crucial skill in team sports, yet remains challenging to measure in controlled settings. For instance, video-based testing of decision making has long neglected the interpersonal interactions between attackers and defenders, therefore it remains unclear to what degree embodied decision-making tested in those conditions reflects that observed in the natural environment. The aim of this study was to examine the extent to which interpersonal interactions influence behaviour in an embodied decision-making task. We designed an interactive avatar defender in a virtual reality setting and conducted an empirical study to evaluate the impact of the interactions. Attackers performed a 1v1 task, and we manipulated the defender’s level of interactivity to compare the attacker’s behaviour to that observed when facing an opponent in situ. Decision-making behaviour was compared across four conditions of increasing interactivity (virtual no-opponent, virtual non-interactive opponent, virtual interactive opponent, and in situ opponent). Results strongly support the idea that adding interactions makes the task more representative of in-situ behaviour. Specifically, key measures of behaviour (e.g., trial duration and number of touches) measured with the virtual-interactive opponent (βTouches=4.3, βDuration=2.7) were much more representative of the in-situ behaviour (βTouches=5.4, βDuration=3.6) than it was against the virtual non-interactive opponent (βTouches=2.9, βDuration=1.84) and in the virtual no-opponent condition (βTouches=2.5 βDuration=1.4). The results validate the call to incorporate interpersonal interactions as a key component of decision-making tasks, and to support this we introduce a novel method for assessing interactive decision-making skills that we make available open source.

13 Pitch Size, Player Numbers, and Playing Rules: How Small-Sided Game Constraints Shape the Training Demands in Male Academy Soccer

Reference: J Strength Cond Res. 2026 Jan 30. doi: 10.1519/JSC.0000000000005351. Online ahead of print.
Authors: Sigrid B H Olthof, Jordi Ferrandis, Vicente de Dios, Andrea Riboli
Summary: Small-sided games (SSGs) are part of daily soccer practice and usually manipulated in pitch size, player number, and playing rules. The aim of this study was to identify constraints that significantly affect the physical demands in SSGs in youth elite soccer players. Training sessions from an under-18 Spanish academy team were monitored, including 87 SSGs. Small-sided games were labelled for area per player (ApP), number of players, type of game, playing duration, goal size, use of floater players and goalkeepers, and number of touches. Relative physical demands were measured as total distance (TD), high-speed running (HSR), sprint distance (SD), and acceleration (ACC) and deceleration (DEC) distance. A linear mixed-effects model analysis was performed estimating the effects of SSG constraints (α set at 0.05). Greater ApP consistently increased TD, HSR, SD, ACC, and DEC. By contrast, increasing the number of players and longer playing duration reduced TD, HSR, ACC, and DEC. In addition, specific playing rules, such as the use of floater players, limited touches, and small goals primarily affected ACC and DEC. These findings highlight the important role of ApPs in shaping physical demands, while also showing that team size, playing duration, and specific playing rules contribute to the physical demands of SSGs. Understanding the magnitude and direction of these manipulations allows coaches to design SSGs more effectively to meet training objectives.

14 The Relationship Between Standing Broad Jump and 30-Meter Sprint in 826 Youth Soccer Players: A Cross-Sectional Study

Reference: J Strength Cond Res. 2026 Jan 30. doi: 10.1519/JSC.0000000000005350. Online ahead of print.
Authors: Marián Škorik, Roman Švantner, David Brűnn, Lukáš Karabin
Summary: Speed and acceleration are essential for offensive and defensive actions in soccer. Given the high cost of advanced sprint measurement systems, alternative field tests such as the standing broad jump (SBJ) may serve as cost-effective tools for assessing horizontal force production. However, the relationship between SBJ and sprint performance across different acceleration phases in youth players remains unclear. This cross-sectional study investigated the relationship between a no-countermovement SBJ and sprint parameters in 826 elite male youth soccer players (U14-U19). Sprint performance was assessed using the 1080 Motion Sprint system, capturing maximum velocity (Vmax), theoretical maximum velocity (V0), maximum horizontal force (F0), maximum power, and maximum ratio of force (RFmax). Average speed (AS) and average force (AF) were analyzed across 3-meter segments for a 30-meter sprint. Pearson’s correlation and linear regression were used, with significance set at p ≤ 0.05. Standing broad jump showed strong correlations with sprint parameters, particularly Vmax, V0, and RFmax (r = 0.68, 0.63, and 0.58; all p < 0.001). The strongest associations between SBJ and AS or AF occurred in the late acceleration phase (9-12 m) across all age groups (AS: r = 0.75; AF: r = 0.66), with the highest correlations in U14 and U15. Regression models revealed that SBJ explained 39.1% of Vmax variance in U14, but only 9.8% in U19. These findings suggest SBJ is a practical and valid tool for evaluating sprint performance in younger players, although its predictive value declines with age because of greater influence of technical and biomechanical sprint factors.

15 Changes in hair cortisol and oxytocin independently associate with positive and negative psychological states in female soccer players

Reference: Front Sports Act Living. 2026 Jan 12:7:1742869. doi: 10.3389/fspor.2025.1742869. eCollection 2025.
Authors: Nodoka Ohara, Hana Kameo, Genta Ochi
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12832784/pdf/fspor-07-1742869.pdf
Summary: This study examined changes in hair cortisol concentration (HCC) and hair oxytocin concentration (HOC) in female athletes and aimed to clarify their relationships with training load, daily life stressors, and mental health indicators. Hair samples were collected from 22 female university soccer players (age: 19.8 ± 0.8 years), and psychological assessments were conducted in February and March 2024. Cortisol and oxytocin were extracted and measured from hair, and their associations with mood states [measured using the Profile of Mood States 2nd Edition (POMS2)], psychological distress [measured using the Kessler Psychological Distress Scale-6 (K6) scale], and self-reported training load were analyzed. Training load and POMS fatigue levels increased significantly from February to March (t = 4.27, P < 0.001 and t = 4.74, P < 0.001, respectively); however, despite these increases in physical demands and perceived fatigue, no significant changes were observed in HCC and HOC. Regression analysis using M-estimation revealed that changes in academic stress were significantly negatively associated with HCC changes (β = -1.04, p = 0.026), and changes in training load showed a positive association trend with HOC changes (β = 0.0003, p = 0.068). Spearman correlation analysis showed a significant negative correlation between HCC changes and POMS vigor changes (rs = -0.44, p = 0.039) and a significant positive correlation between HOC changes and K6 scale changes (rs = 0.43, p = 0.043). No significant correlation was found between HCC and HOC. HCC and HOC fluctuated independently and were associated with distinct psychological outcomes: HCC changes correlated with vigor, while HOC changes correlated with psychological distress. These findings suggest that each hormone may capture different dimensions of chronic stress and psychological functioning. Combined measurement of HCC and HOC may be useful in assessing chronic stress in female soccer players, providing complementary information for athlete health management.

16 Socceromics: A Systematic Review of Omics Technologies to Optimize Performance and Health in Soccer

Reference: Int J Mol Sci. 2026 Jan 12;27(2):749. doi: 10.3390/ijms27020749.
Authors: Adam Owen, Halil İbrahim Ceylan, Piotr Zmijewski, Carlo Biz, Giovanni Sciarretta, Alessandro Rossin, Pietro Ruggieri, Andrea De Giorgio, Carlo Trompetto, Nicola Luigi Bragazzi, Luca Puce
Download link: https://www.mdpi.com/1422-0067/27/2/749
Summary: The integration of omics technologies, including genomics, proteomics, metabolomics, and microbiomics, has transformed sports science, particularly soccer, by providing new opportunities to optimize player performance, reduce injury risk, and enhance recovery. This systematic literature review was conducted in accordance with PRISMA 2020 guidelines and structured using the PICOS/PECOS framework. Comprehensive searches were performed in PubMed, Scopus, and Web of Science up to August 2025. Eligible studies were peer-reviewed original research involving professional or elite soccer players that applied at least one omics approach to outcomes related to performance, health, recovery, or injury prevention. Reviews, conference abstracts, editorials, and studies not involving soccer or omics technologies were excluded. A total of 139 studies met the inclusion criteria. Across the included studies, a total of 19,449 participants were analyzed. Genomic investigations identified numerous single-nucleotide polymorphisms (SNPs) spanning key biological pathways. Cardiovascular and vascular genes (e.g., ACE, AGT, NOS3, VEGF, ADRA2A, ADRB1-3) were associated with endurance, cardiovascular regulation, and recovery. Genes related to muscle structure, metabolism, and hypertrophy (e.g., ACTN3, CKM, MLCK, TRIM63, TTN-AS1, HIF1A, MSTN, MCT1, AMPD1) were linked to sprint performance, metabolic efficiency, and muscle injury susceptibility. Neurotransmission-related genes (BDNF, COMT, DRD1-3, DBH, SLC6A4, HTR2A, APOE) influenced motivation, fatigue, cognitive performance, and brain injury recovery. Connective tissue and extracellular matrix genes (COL1A1, COL1A2, COL2A1, COL5A1, COL12A1, COL22A1, ELN, EMILIN1, TNC, MMP3, GEFT, LIF, HGF) were implicated in ligament, tendon, and muscle injury risk. Energy metabolism and mitochondrial function genes (PPARA, PPARG, PPARD, PPARGC1A, UCP1-3, FTO, TFAM) shaped endurance capacity, substrate utilization, and body composition. Oxidative stress and detoxification pathways (GSTM1, GSTP1, GSTT1, NRF2) influenced recovery and resilience, while bone-related variants (VDR, P2RX7, RANK/RANKL/OPG) were associated with bone density and remodeling. Beyond genomics, proteomics identified markers of muscle damage and repair, metabolomics characterized fatigue- and energy-related signatures, and microbiomics revealed links between gut microbial diversity, recovery, and physiological resilience. Evidence from omics research in soccer supports the potential for individualized approaches to training, nutrition, recovery, and injury prevention. By integrating genomics, proteomics, metabolomics, and microbiomics data, clubs and sports practitioners may design precision strategies tailored to each player’s biological profile. Future research should expand on multi-omics integration, explore gene-environment interactions, and improve representation across sexes, age groups, and competitive levels to advance precision sports medicine in soccer.

17 Sleep, Stress, and Recovery as Predictors of Injury Risk in Soccer Players: A Systematic Review

Reference: Healthcare (Basel). 2026 Jan 17;14(2):236. doi: 10.3390/healthcare14020236.
Authors: Enrique Cantón, Joel Raga, David Peris-Delcampo
Download link: https://www.mdpi.com/2227-9032/14/2/236
Summary: Sleep is an essential component in the recovery, performance, and injury prevention processes of soccer players. Associated psychological variables, such as the balance between stress and recovery, have been less explored, despite their potential influence on rest and injury vulnerability. This study aims to examine the relationship between sleep quality, quantity, and chronotype and injury risk in soccer players, also incorporating the modulating role of stress and recovery. A PRISMA systematic review was conducted using searches in ScienceDirect, PubMed, Ovid, EBSCO, MDPI, Springer Nature Link, SPORTDiscuss (full text), and Dialnet. Original studies and reviews on sleep and its relationship with sports injuries in soccer players or comparable athletic populations were included. Eighteen studies were selected that addressed sleep indicators (quality, quantity, chronotype), injury incidence, and, to a lesser extent, measures of stress and recovery using instruments such as the RESTQ-Sport or wellness questionnaires. There is evidence of an association between poor sleep quality or quantity and an increased risk of injury or illness. Chronotype is an emerging variable of interest, although still insufficiently researched. Regarding stress and recovery, direct evidence is limited, although studies that address this issue show that an imbalance between these two dimensions negatively impacts sleep quality and increases susceptibility to injury. Sleep and the stress-recovery balance are key and interdependent factors in the risk of injury in soccer players. Future research should consider including these variables to further understand the mechanisms underlying the injury process and optimize prevention and recovery strategies.

18 Sex-Specific Associations Between Repetitive Head Impact Exposure and Cerebral Blood Flow Among Active Amateur Soccer Players

Reference: J Neurotrauma. 2026 Jan 27:8977151251408823. doi: 10.1177/08977151251408823. Online ahead of print.
Authors: Zheyuan Li, Alberto Villagran Asiares, Anja Betz, Luisa S Schuhmacher, Julie Joyce, Lasse Lohmann, Nico Sollmann, Inga K Koerte
Download link: https://journals.sagepub.com/doi/epub/10.1177/08977151251408823
Summary: Repetitive head impacts (RHIs) in soccer have been associated with long-term risk for neurodegenerative disease. The pathophysiology is largely unknown. This study aims to investigate alterations in cerebral blood flow (CBF) in athletes exposed to RHI compared with athlete controls (CTL). Given that females are known to exhibit higher CBF than males, we also explore sex-specific differences. Finally, we investigate the relationship between CBF and neuropsychological functioning and RHI measures. This study includes 82 amateur athletes (mean age 22.8 ± 1.6 years; 48.9% female). Participants underwent 3T magnetic resonance imaging and completed neuropsychological testing, including questionnaires on stress, resilience, and sleep quality, and computerized assessment of executive function, memory, and processing speed. CBF was assessed using MR pulsed arterial spin labeling. Analysis of covariance was applied to assess the effect of RHI exposure and sex on CBF. Associations between CBF and neuropsychological functioning were analyzed using linear regression models. The analysis was conducted hierarchically, beginning with global gray matter CBF (level 1), followed by cortical and deep gray matter (level 2), and finally brain lobes (level 3). Correction for multiple comparisons was applied at each hierarchical level using false discovery rate, with a significance threshold set at p < 0.05 after correction. We found higher CBF in athletes with RHI exposure (RHI group) compared with athletes with <5 years of exposure to RHI (CTL group; Δ 95% confidence interval [95% CI] = 3.9 [0.5, 7.3] mL/100g/min, p = 0.027). Female athletes with RHI exposure exhibited higher CBF in the global gray matter compared with female CTL (Δ[95% CI] = 6.6 [1.6, 11.5] mL/100g/min, p = 0.013). Among males, individuals with RHI exposure demonstrated higher CBF in the occipital lobe compared with male CTL (Δ[95% CI] = 4.9 [0.3, 9.5] mL/100g/min, p = 0.047). There were no statistically significant associations between CBF and neuropsychological functioning. In the RHI group, years of soccer play were positively associated with whole-brain CBF. Results from this study suggest an association between RHI exposure and higher CBF, a measure of brain activity. Furthermore, we report sex-specific patterns of higher CBF in individuals exposed to RHI, with more widespread elevated CBF in women and more localized higher CBF in men. While these findings highlight the importance of investigating sex-specific effects, there were no associations between CBF and neuropsychological functioning. Future studies are warranted to determine the clinical relevance of the observed sex-specific effects to RHI.

19 Reactive Training in Enhancing Technical Performance and Modulating Cortisol Biomarkers in Competitive Soccer Players

Reference: J Strength Cond Res. 2026 Jan 28. doi: 10.1519/JSC.0000000000005390. Online ahead of print.
Authors: Marco Centorbi, Alessandro Medoro, Luca Modolo, Gloria Di Claudio, Giulia Di Martino, Carlo Della Valle, Andrea Buonsenso, Nicola Marziliano, Sergio Davinelli, Giuseppe Calcagno, Alessandra di Cagno, Giovanni Fiorilli
Summary: In soccer, the ability to perceive, process, and integrate external and internal stimuli is crucial for the development of players‘ technical, physical, and tactical skills. This study aimed to assess the effectiveness of an Experimental Warm-Up (EWU) protocol for enhancing soccer-specific technical and physical skills while optimizing cortisol levels in elite soccer players. Thirty-two male soccer players (age: 24.7 ± 3.1 years) from 2 elite teams were assigned to an experimental group (EG; n = 18) or a control group (CG; n = 14). During the 12 weeks, along with their regular warm-up (WU), the EG performed an EWU consisting of 4 progressive coordination exercises, 4 times per week. The CG maintained their usual WU schedule. Technical abilities were assessed pre- and postintervention using the Y-Planned and Y-React, React Index (Y-REACT minus Y-PLAN), Illinois Change of Direction with and without ball (ICODT-BALL and ICODT), Technical Index (ICODT-BALL minus ICODT), and Loughborough Soccer Shooting (SHOT) tests. Urine samples were collected before and after the 12-week intervention to measure cortisol levels. The RM-ANOVA revealed significant improvements from pre- to postassessment in the EG for the ICODT-BALL, Technical Index, Y-REACT, React Index, and SHOT (p < 0.001). These improvements were significantly greater than those in the CG. In addition, the EG showed a significant reduction in cortisol levels from pre- to postintervention (p = 0.0007) and compared with the CG (p = 0.003). These findings indicate that incorporating coordinative training into WU improves technical performance and agility in soccer, supporting better regulation of cortisol levels in elite players.

20 Incorporating Squat-Based Training into the Warm-Up Twice Weekly Improves Sprint, Jump, and Change-of-Direction Performance in Young Soccer Players

Reference: Sports (Basel). 2026 Jan 14;14(1):40. doi: 10.3390/sports14010040.
Authors: Okba Selmi, Hamza Marzouki, Mohamed Amine Rahmoune, Elena Adelina Panaet, Bogdan Alexandru Antohe, Cristina Ioana Alexe, Ana Maria Vulpe, Anissa Bouassida
Download link: https://www.mdpi.com/2075-4663/14/1/40
Summary: Understanding the long-term effectiveness of warm-up strategies is essential for enhancing neuromuscular performance in youth soccer players. This study examined the long-term effects of integrating squat exercises into the final phase of the warm-up over nine weeks on sprint, jump, change-of-direction (COD), and aerobic performance in youth soccer players. Twenty-four male U17 players were randomly assigned to either a squat-based warm-up (experimental group [EG]) or a rondo-based warm-up (control group [CG]). The EG trained twice weekly using 3-4 sets of 4-12 repetitions at progressively increasing intensities (50-85% of 1-RM). Performance was assessed pre- and post-intervention using 10 and 30 m sprint, squat jump (SJ), countermovement (CMJ), standing long jump (SLJ), 5-jump (5JT), T-half (COD), and VAMEVAL tests. The EG showed small to large significant gains in sprint (10 m: -2.21%, Cohen’s d [d] = 1; 30 m: -1.6%, d = 0.58), jumping (SJ: +9.29%, d = 1.23; CMJ: +12.08%, d = 1.83; SLJ: +7.14%, d = 0.8; 5JT: +2.33%, d = 0.32), and COD (-1.41%, d = 0.32), while aerobic endurance showed no significant change (p > 0.05). The CG showed no significant improvements (p > 0.05). Overall, integrating brief, progressive squat exercises at the end of warm-ups twice weekly led to chronic improvements in explosive neuromuscular performance, with minimal impact on aerobic endurance.

21 Comparative Effects of Repeated Linear Sprint and Change-of-Direction Speed Training on Performance, Perceived Exertion and Enjoyment in Youth Soccer Players

Reference: Sports (Basel). 2026 Jan 8;14(1):33. doi: 10.3390/sports14010033.
Authors: Okba Selmi, Mohamed Amine Rahmoune, Hamza Marzouki, Bilel Cherni, Anissa Bouassida, Antonella Muscella, Santo Marsigliante, Jolita Vveinhardt, Wafa Douzi
Download link: https://www.mdpi.com/2075-4663/14/1/33
Summary: Youth soccer requires an integrated approach combining technical-tactical, physical, and psychological components to enhance performance and long-term engagement. Although Repeated Linear Sprint Training (LRST) and Repeated Change of Direction Speed (RCOD) training are widely used to improve fitness, direct comparisons of their effects on physical performance and perceptual responses in adolescent players remain limited. This study compared the effects of an 8-week LRST versus RCOD training program on physical performance, perceived exertion, and enjoyment in youth soccer players. Twenty-six male players were randomly assigned to an LRST group (n = 13) or an RCOD group (n = 13). Both groups completed two weekly sessions of their assigned training in addition to regular soccer practice. Pre- and post-intervention assessments included acceleration and sprint speed, change-of-direction (COD) performance (T-Half Test [THT], Illinois Agility Test [IAT]), lower-limb power (Five-Jump Test [5JT], Squat Jump [SJ], Countermovement Jump [CMJ]), and endurance-intensive fitness. Enjoyment and session-RPE were recorded after each training session. Both groups improved across all physical measures (main effect of time, p < 0.0001). Significant time × group interactions favored RCOD for THT (~1.6%), IAT (~1.1%), 5JT (~2.3%), CMJ (~5.2%), and SJ (~6.3%), with no overall main effect of group. Enjoyment was consistently higher in the RCOD group (p < 0.0001), while session-RPE did not differ between groups. In youth soccer, both LRST and RCOD effectively enhance physical performance. However, RCOD appears more effective for improving pre-planned COD and explosive performance while eliciting greater enjoyment without increasing perceived exertion. Incorporating structured RCOD training alongside linear sprint work may represent a practical strategy to optimize physical development and sustain player engagement.