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 Elevating recreational soccer to improve population health in the United States: the time is now

Reference: Front Public Health. 2024 Oct 18:12:1406878. doi: 10.3389/fpubh.2024.1406878. eCollection 2024.
Authors: José M Oliva-Lozano, George T Chiampas, Rick Cost, John Sullivan, Felipe Lobelo 
Download link: https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2024.1406878/full

2 Reliability and validity of My Jump 2® app to measure the vertical jump in visually impaired five-a-side soccer athletes

Reference: PeerJ. 2024 Oct 29:12:e18170. doi: 10.7717/peerj.18170. eCollection 2024.
Authors: Julio Cesar Silva, Kalinne Fernandes Silva, Vitor Bruno Torres, Maria Socorro Cirilo-Sousa, Alexandre Igor Araripe Medeiros, Jacques Eanes Esmeraldo Melo, Gilmário Ricarte Batista
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11529592/pdf/peerj-12-18170.pdf
Summary: Although My Jump 2 ® consistently presented excellent values of reliability and validity when compared to force platforms (FPs) and contact mats, to date no scientific investigation assessed the validity and reliability of My Jump 2 ® to measure jump height in visually impaired five-a-side soccer athletes. Thus, the study aimed at analyzing the validity and reliability of the My Jump 2® to measure the vertical jump of five-a-side soccer athletes. Twelve visually impaired five-a-side soccer athletes, volunteered for this study. Each player performed five countermovement jumps (CMJs) and squat jumps (SJs) on a contact platform (CP) while they were simultaneously recorded using My Jump 2 ®. There was almost perfect agreement between the My Jump 2® and the contact platform measurements of CMJ (intraclass correlation coefficient = 0.99; p < 0.001) and SJ (intraclass correlation coefficient = 0.99; p < 0.001), heights for athletes during the first and second measurement days. Bland-Altman analysis showed a bias of 0.25 ± 0.5 cm; maximum SD = 1.3; minimum SD = -0.88 for CMJ, while that Bland-Altman analysis showed bias 0.18 ± 0.5 cm; maximum SD = 1.3; minimum SD = -0.96, for SJ. We can conclude that the My Jump 2® is a valid and reliable method to measure CMJ and SJ in visually impaired five-a-side soccer athletes.

3 Injuries Following COVID-19 Infection in Academy-level Male Youth Soccer Players

Reference: J Pediatr Orthop. 2024 Nov 4. doi: 10.1097/BPO.0000000000002845. Online ahead of print.
Authors: Kyle Brougham, Jonathan R Warren, McKenna Noe, Brian R Lee, Shannon Margherio, James Roberson, Brian Harvey
Summary: Injury epidemiology data are key to injury prevention strategy development. Most such data surrounding the COVID-19 pandemic compare team injury data during the pandemic to that before the pandemic; few investigate injuries by infection status and even less involve academy-level organizations. We hypothesized that in male youth developmental academy-level soccer players, the rate of injury would be higher following COVID-19 infection than in the uninfected. Retrospective cohort study involving 141 male youth athletes from a single midwestern US developmental soccer academy during the spring 2022 soccer season. Injury data was gathered prospectively and analyzed retrospectively. Injury rate (incidence per 1000 playing hours), type, location, severity, mechanism, and mode of play were compared between COVID-19-positive and -negative athletes. Thirty-four (24.11%) of 141 athletes tested positive for COVID-19. Of those 34, 20 (58.8%) sustained at least 1 injury, totaling 30 injuries. Of the 107 (75.89%) uninfected athletes, 30 (28.04%) sustained at least 1 injury, totaling 37 injuries. COVID-19-positive athletes sustained injuries at higher rates (7.10, 95% CI: 4.79-10.14) than uninfected athletes (2.71, 95% CI: 1.91-3.74), with an infected to uninfected adjusted injury rate ratio of 2.08 (95% CI: 1.20-3.59, P=0.008). COVID-19 positive players were 2.78 times more likely to sustain an injury following their infection than uninfected players (95% CI: 1.14-6.96, P=0.026). There were no significant differences in injury type (P=0.515), location (P=0.319), severity (P=0.679), mechanism (P=0.225), or mode of play (P=0.557) between groups. Among academy-level youth soccer athletes, injury rate increased significantly after COVID-19 infection; injury patterns were similar.

4 Accuracy Standards of Wearable Technologies for Assessment of Soccer Kicking: Protocol for a Systematic Literature Review

Reference: JMIR Res Protoc. 2024 Nov 4:13:e57433. doi: 10.2196/57433.
Authors: Luiz H Palucci Vieira, Filipe Manuel Clemente, Felipe Armando Chang Marquez, Walter Manuel Rea Olivares, Kelly R Vargas Villafuerte, Felipe P Carpes
Download link: https://preprints.jmir.org/preprint/57433?__hstc=178719527.c0be3152b41f8339073812a2cd92e2a1.1731256738532.1731256738532.1731256738532.1&__hssc=178719527.1.1731256738533&__hsfp=2388203918
Summary: Wearable technology is widely applied in performance monitoring, an integral part of sports and exercise sciences. The kick movement in soccer exemplifies a sports technique that could benefit from appropriate biomechanics assessment methodologies. However, the accuracy of wearables in quantifying soccer kick mechanics, particularly under field conditions, remains unclear. This study aims to present a protocol for a systematic review to discuss the measurement properties (validity, reliability, and/or accuracy aspects) of wearable technology systems explicitly used to measure ball-kicking features in soccer. This review protocol was preregistered in the Open Science Framework. A total of 2 authors will perform searches in major electronic databases using specific keyword combinations in PubMed, Physical Therapy and Sports Medicine, Web of Science, ProQuest, IEEE Xplore, EBSCOHost, and Scopus. Following a specific population, intervention, comparison, outcome framework (population: soccer players and/or collected human data in a football-related environment; intervention: at least 1 wearable used; comparator: criterion measures, repeated testing sessions and/or actual values; outcome: ball kicking data), studies will be screened based on predetermined inclusion and exclusion criteria. The methodological quality of the included studies will be assessed using the „consensus-based standards for the selection of health measurement instruments“ checklist (in studies concerning validity or reliability) or the „quality assessment of diagnostic accuracy studies“ tool (in studies concerning accuracy). Data extraction will be conducted to determine the level of evidence according to the „best evidence synthesis method,“ and an evidence gap map will be constructed. The Cohen κ coefficient will be used to estimate the interevaluator agreement. This ongoing systematic review has completed database searches and is currently in the screening phase. Depending on the number and consistency of studies, results may be presented by meta-analysis or qualitative synthesis, with subgroup analyses considering factors such as gender, age, and playing level. The final results are expected by July 2024, with manuscript submission anticipated by November 2024. Our study will provide a comprehensive summary of the highest level of evidence available on the use of wearables for the assessment of soccer kick mechanics, providing practical guidance for athletes and sports sciences professionals regarding the validity and reliability aspects of using wearable technology to measure ball-kicking features in soccer.

5 Relationship between fat-free mass index and nutrient intake in protein supplement user among Japanese collegiate soccer athletes

Reference: Phys Act Nutr. 2024 Sep;28(3):36-42. doi: 10.20463/pan.2024.0021. Epub 2024 Sep 30.
Authors: Ryunosuke Takahashi, Yukiko Kobayashi, Takako Fujii, Shino Kuwabara, Yuko Segawa-Yoshimoto, Wataru Aoi, Masashi Kuwahata
Download link: https://e-pan.org/upload/pdf/pan-2024-0021.pdf
Summary: Protein supplements are widely used by athletes, prompting the scrutiny of their impact on low energy availability. This study investigated whether habitual protein supplement use is linked to physical characteristics and nutrient intake in Japanese university soccer athletes. In addition, an attempt was made to examine the differences in physical characteristics and nutrient intake according to muscle mass in protein supplement users using the fat-free mass index (FFMI), which reflects muscle mass. A dietary survey, physical activity survey, and measurement of the physical characteristics of 38 Japanese collegiate soccer players were conducted. The habitual protein supplement utilization rate among the participants was 50%, and the participants exhibited an FFMI of 19.2 ± 1.3 kg/m2. Significant disparities between the two groups were noted in exercise energy expenditure (p = 0.023); carbohydrates (p = 0.039); copper (p = 0.003); and vitamins B1 (p = 0.016), B2 (p = 0.040), B6 (p = 0.003), C (p = 0.012), and D (p = 0.033), with higher levels observed in the protein-consuming cohort compared to the non-consuming cohort. Protein supplement users (n = 15) were stratified into two groups based on the median FFMI of the entire population (18.9 kg/m2). While the energy balance ratios were comparable between the groups, the high FFMI group tended to exhibit elevated energy intake (p = 0.169), consumption (p = 0.076), and carbohydrate consumption (p = 0.092), compared to the low FFMI group. These findings suggest that adequate carbohydrate and protein intakes are crucial for preserving or augmenting muscle mass in young Japanese soccer athletes, including those consuming protein supplements.

6 Effects of Short- Versus Long-Distance Repeated-Sprint Ability Training on Physical Performance in Youth Male Soccer Players

Reference: Pediatr Exerc Sci. 2024 Nov 6:1-8. doi: 10.1123/pes.2023-0144. Online ahead of print.
Authors: Diego Fernández-Penedo, Alberto García-Santamaría, Miguel Lorenzo-Martínez, Samuel Carrera, Alexis Padrón-Cabo, Pablo B Costa, Ezequiel Rey
Summary: The aim was too examine the effects of 2 repeated-sprint ability (RSA) training protocols using short sprints (15 m, RSA-15) and long sprints (30 m, RSA-30) on sprinting, maneuverability, intermittent endurance, and RSA in young soccer players. Thirty-one male U-18 players were randomly assigned to the RSA-15 (n = 15) and RSA-30 (n = 16) groups. The intervention programs were conducted twice a week over 6 weeks. Significant improvements in 5-, 10-, and 20-m sprints, as well as the Yo-Yo test, from pretest to posttest in the RSA-15 group (8.17%, 5.92%, 5.02%, and 16.59%) and the RSA-30 group (9.21%, 7.44%, 5.64%, and 18.79%) were observed. Players in the RSA-30 group demonstrated a significant enhancement in maneuverability from pretest to posttest (4.42%). Both the RSA-15 and RSA-30 protocols resulted in enhancements in RSA, particularly in terms of total time (4.71% and 2.30%, respectively), average time (4.71% and 2.30%, respectively), and fastest time (2.97% and 2.32%, respectively). However, only the RSA-15 protocol significantly enhanced the RSA percentage of decrement (24.06%). The present results provide further evidence that, if the primary focus is to maximize RSA performance, RSA-15 should be preferred. When the goal is to enhance maneuverability, implementing RSA-30 is recommended over using RSA-15.

7 The effects of acute caffeine ingestion on decision-making and pass accuracy in young soccer players: A preliminary randomized controlled trial

Reference: Behav Brain Res. 2023 Oct 27:114732. doi: 10.1016/j.bbr.2023.114732. Online ahead of print.
Authors: Negar Jafari, Mohsen Salesi, Pooya Soltani, Davoud Fazeli
Download link: https://pdf.sciencedirectassets.com/271031/1-s2.0-S0166432823X00187/1-s2.0-S0166432823004503/main.pdf?X-Amz-Security-Token=IQoJb3JpZ2luX2VjEAkaCXVzLWVhc3QtMSJGMEQCIBh3dKqn6pKNNHiyYOOjatWCFqH9ek0Mv6NiD9SfeIHwAiBvjsr8ihI6UTkmsV7Vy56L%2BFSVDUOxpOhCauma2Rgoxiq8BQiS%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F8BEAUaDDA1OTAwMzU0Njg2NSIMni%2BDgKV7acoG76pxKpAFQKItyVx8ZL8glKYZGX0Vjt2G7rZn7nInpIzYBeDaJy4Qg1eGe1%2Bu6Xyg7Co27dJbR%2B%2FkO82%2F6LWnTX82PPrvjeV4AyrAY0nb5xLQ493TI4nolDA7b6xw9DabP74Qo2XQRdT75gNfDdCIaJ40FtlWtzT1L3plt5YnxC%2FcxTperDIr437hFh60ySK0%2ByUcWooLV2yuvdG4e%2FPYuD1oCzUOzm0SATogs2GQmIt%2BnE1ZfBJ92g5GmMRxZkTKDMP91jC%2FFXMRXL6VKGdJOEjoFwyVu3ukkcQOGcmjmJFd38Tbq5V5SJyGFyIhqO%2FZendKKfRxp%2FMrC7Mmq%2FVt37f4aR1QcVEcbyQARhw3bPgMZ9%2B3iDxJBRzTiBFvh6xLBrHfRz1PYc25BSE2ZSGRnR5%2FyJjRxfmTSR6QPDQZ7BdgZTSVJ9a1GvNDnR50RsyqDol6226xH3JIPrlK%2BLk71VEKcYUeSLpa7ZG58w1VE8o9mCegPT1NYTYbSA%2FfJDu8TIvoGirVjuIwcTPawdZcX7bFuGLbz7p1pVVJ92QL7JVfdrhrWTi%2F44qj8beH6269fON895Vsz4c4y4eAhYTy1218SCVbtoZs%2Flykbo6nvWK%2FNf2LpB3Z9W3JkZ5u90TtDRe%2FKlEwZplD3nn181k4Br61v2a8x%2Fjlv4iKBTdOF%2BN%2Fsft8P3qLD1f0VfoNSC2tAfH9jg8qufxlN08fzWGPcgPfDOXzh%2FJIgAkLdoXQ1XUhbFWniwNz5LeptKHtbl4Hv89sRO153rIXBE0nuEp84RL39%2B3apEO54ewM9K81UcQZ5tpBTkodlrt01nXcmwODS4LEcb4WLmFwq4FL%2Bjk5whSgIz%2FcLSkCkq20euOXwvuOpTJAyL4wr7vDuQY6sgHckFP4Nmi9Rvrn%2Bmh2tndts1IhiAlpb8j37W%2BSfVI2iC8sjKrlwQi2akT97m15jKITwmRDaYEpo%2F%2FvS6J8dAQet5vUcT0FEBud124wW07wiyqXpr7%2B7Ur0mF2m7RTYwE2hfxs9d2KfByTPLMG7t92yb1tRzNkEoXy1hE1OQiJe9Ya6rTNQIJk%2BonZOJ3RoTIpxM2WN5%2F8Wgca%2FtEx6TR7OUCoh0oDwvmr28hyJC7FY1ZAL&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20241110T164553Z&X-Amz-SignedHeaders=host&X-Amz-Expires=300&X-Amz-Credential=ASIAQ3PHCVTYT5RDRGGT%2F20241110%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=ed2611c75cc3d28ccb47706305a1593024c4be7af5c6ae9370dbbd1044dd37fd&hash=28cdfc97c50f998394529ee1ffcf3ecb9f204468c3b6fb78a86e3f69d3bdcf88&host=68042c943591013ac2b2430a89b270f6af2c76d8dfd086a07176afe7c76c2c61&pii=S0166432823004503&tid=spdf-f4b68906-e738-4d92-a2a7-d23e3a7f6b8a&sid=d19a02fd99e2054e9e8af121d657d8952d2dgxrqa&type=client&tsoh=d3d3LnNjaWVuY2VkaXJlY3QuY29t&ua=1e035b0b52545b54015652&rr=8e0783f80ca7d2f3&cc=de
Summary: Caffeine has been shown to benefit physical aspects of different sports. In this paper, we aimed to understand the effects of caffeine on decision-making and the accuracy of soccer passes. Twelve young soccer players (16-17 years old and 20.8±2.7kg/m2 BMI) completed the tasks once after taking 3mg/kg body mass of caffeine (CAF) and once after consuming similar amounts of placebo (PLA). For the decision-making task, participants were asked to determine the best outcome of ten simulated pre-recorded soccer events. For the soccer pass accuracy, participants performed five short- (10m) and five long passes (30m), as well as the Loughborough Soccer Passing Test. Although not statistically significant, participants were 1.67% more accurate in short- and 13.48% more accurate in long passes when they consumed caffeine compared to the placebo (14.67±2.74 vs. 14.50±2.97, p=0.34, g=0.27 and 7.50±2.84 vs. 6.83±3.13, p=0.60, g=0.14, respectively). However, participants‘ decision-making was 7.14% and LSPT scores were 3.49% lower when they consumed caffeine compared to the placebo (29.50±3.09 vs. 30.67±2.93, p=0.28, g=-0.30 and 55.38±11.91 vs. 57.48±12.13, p=0.08, g=-0.51 respectively). In conclusion, while the short pass accuracy remained consistent among almost all participants before and after caffeine consumption, the performance varied in the case of long passes. Moreover, most of the participants scored lower on decision-making and LSPT after consuming caffeine. This may suggest that more complex tasks with a higher number of passes might negatively be affected by low doses of caffeine ingested one hour before playing soccer. Future studies are required to elucidate the effects of caffeine consumption on distinct cognitive and passing tasks.

8 Professional Male Soccer Players‘ Perspectives of the Nutrition Culture Within an English Premier League Football Club: A Qualitative Exploration Using Bourdieu’s Concepts of Habitus, Capital and Field

Reference: Sports Med. 2024 Nov 3. doi: 10.1007/s40279-024-02134-w. Online ahead of print.
Authors: Wee Lun Foo, Emma Tester, Graeme L Close, Colum J Cronin, James P Morton
Download link: https://link.springer.com/content/pdf/10.1007/s40279-024-02134-w.pdf
Summary: Professional soccer players‘ self-reported dietary intakes often do not meet recommended sport nutrition guidelines. Although behaviour change models have previously explored barriers and enablers to nutritional adherence, the cultural factors influencing players‘ nutritional habits also warrant investigation. Accordingly, we aimed to explore players‘ perceptions of the nutrition culture within the professional soccer environment. An interpretivist paradigm, which emphasises that reality is subjectively and socially constructed, underpins this study. Qualitative, face-to-face semi-structured interviews (comprising open-ended questions) were conducted with purposively sampled male soccer players from the English Premier League (EPL) (five British, five migrant; mean age: 26 ± 6 years; mean EPL appearances: 106 ± 129). Data were abductively analysed using thematic analysis according to Bourdieu’s concepts of habitus, capital, field and doxa practices. This study revealed five key themes: (1) players‘ habitus, as shaped by familial, ethnic and religious backgrounds, influences their dietary habits; (2) social capital, via managers (head coaches), teammates and online influences, impact players‘ dietary practices; (3) the increase in both soccer clubs‘ and players‘ economic capitals has advanced nutrition provision; (4) an unequal distribution of economic capitals has led to hierarchical practice in the performance nutrition field with personalised nutrition being somewhat enacted at the higher levels; and (5) body composition measurement is a ‚doxic‘ practice in professional soccer that warrants challenge. Soccer players‘ habitual nutritional practices are influenced by personal upbringing and the club context, including economic resources and social capital from managers. The performance nutrition field within professional soccer is also shaped by stakeholders‘ doxic beliefs surrounding the perceived optimal body composition of players, with managers exerting social capital.

9 Injury incidence, prevalence, and burden in an Argentinian male youth soccer academy: one-season descriptive study

Reference: Phys Sportsmed. 2024 Nov 2. doi: 10.1080/00913847.2024.2425265. Online ahead of print.
Authors: Matías Dominguez, Juan Pablo Rico, Franco Tedesco, Eduardo Tondelli
Summary: The aim was to prospectively describe the incidence, severity, and burden of injuries in the youth divisions of an Argentinian professional soccer club during a competitive season. 212 male soccer academy players were grouped by age categories and maturity offset as pre-peak height velocity (PHV), circa-PHV and post-PHV. Injury characteristics were recorded as the International Olympic Committee suggests. A total of 235 time-loss injuries were sustained by 101 different players. The overall injury incidence rate was of 5.8 injuries per 1000 hours (h), with a training and match injury incidence rate of 4.9 and 9.7 injuries per 1000 h, respectively. The prevalence over the season was 47%. Most of the injuries (202) affected the lower limbs (86.6%) and most of them were classified as muscle/tendon injuries (n = 117, 49.8%). Hamstring structural injury was the diagnosis with the highest burden in both circa and post-PHV groups. The incidence, prevalence and injury burden reported in this study would add valuable information to Argentinians‘ youth soccer institutions. Post-PHV players had higher incidence, severity and burden compared to circa-PHV. Structural/functional injuries to the muscle/tendon represented the highest burden for type of injuries (41.1 per 1000 h), suggesting a need for implementing preventive measures.

10 Effects of hyperbaric oxygen therapy on recovery after a football match in young players: a double-blind randomized controlled trial

Reference: Front Physiol. 2024 Oct 22:15:1483142. doi: 10.3389/fphys.2024.1483142. eCollection 2024.
Authors: Marko Gušić, Tomislav Stantić, Anja Lazić, Slobodan Andrašić, Bart Roelands, Špela Bogataj
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11534614/pdf/fphys-15-1483142.pdf
Summary: Football is a physically demanding sport that requires effective recovery strategies to maintain performance level and prevent injuries. This study investigated if a single 1-h hyperbaric oxygen therapy (HBOT) session affects recovery and performance after a football match in elite youth players. Twenty elite youth football players (age 17.3 ± 0.5 years) were randomly assigned to a HBOT group or a control group (CON). They played a 90-min football game and underwent either a 60-min HBOT or placebo intervention. Before (T1), at the end of the match (T2), 1 h after HBOT or CON session (T3), and 12 h after HBOT session (T4), subjects underwent biochemical (serum samples (myoglobin (MB), creatine kinase (CK), lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and aspartate aminotransferase (AST)) and performance measurements (linear speed at 5 m, 10 m and 20 m, squat jump (SJ), countermovement jump (CMJ) and countermovement jump with arm swing (CMJa)). The Hooper Index (HI) was collected and heart rate was measured during the game. The football match induced significant increases in all biochemical markers, but no significant differences were found between the HBOT and control group in biochemical or performance parameters at any time point. However, there was a significant interaction effect between time and group for HI (p = 0.012, η2 = 0.124), with the HBOT group showing significantly lower HI values (8.6 ± 2.41) than the control group (11.0 ± 3.23) at 1 h post-HBOT. A single 1-h session of HBOT did not significantly affect recovery or performance parameters in elite youth football players, though it did show a moderate positive affect on the HI at 1 h post-HBOT. Further studies should explore the impact of either longer or sequential HBOT sessions on recovery.

11 Risk for low energy availability, disordered eating and sleep disturbance among female football players

Reference: Phys Act Nutr. 2024 Sep;28(3):43-51. doi: 10.20463/pan.2024.0022. Epub 2024 Sep 30.
Authors: Alisha Saifi, Gulshan Lal Khanna, Kommi Kalpana
Download link: https://e-pan.org/upload/pdf/pan-2024-0022.pdf
Summary: Low energy availability (LEA) and mental health issues are prevalent among female athletes and can have adverse effects on health and sports performance. This study aimed to assess energy availability and, mental health status (depression, anxiety, sleep deprivation, drug misuse, alcohol misuse, and disordered eating) among female football players. Despite the availability of validated tools for the triads and REDs, few studies have focused on the prevalence of LEA and mental health in female football players. Furthermore, limited information is available on LEA and its consequences in India. Professional female football players (n=25) aged 19-30 years were recruited using incidental sampling. LEA was estimated based on energy availability [energy intake – activity energy expenditure] and LEA female questionnaire (LEAF-Q). Sports mental health assessment tool-1 (SMHAT-1) was used to assess the mental health status. Descriptive statistics and chi square test were used to test the hypotheses. According to the factorial method and LEAF-Q, 24% and 12% of players had LEA, respectively. LEA symptoms, such as decreased gastrointestinal and menstrual function, were observed in 16% of participants, while 8% had a history of injury. 44% of the participants exhibited poor mental health. Sleep disturbance (12%) and disordered eating (44%), were among the most common mental health issues. No significant difference was found between LEA, disordered eating, and sleep disturbance. Female football players were more likely to develop LEA and mental health disorders, such as disordered eating and sleep disturbance. LEA was not linked with disordered eating or sleep disturbance. Early detection of LEA and effective intervention enhances the health and performance of female football players.

12 The Influence of Competitive Level on Sleep Quality and Quality of Life in Adolescent Soccer Players

Reference: Cureus. 2024 Oct 13;16(10):e71395. doi: 10.7759/cureus.71395. eCollection 2024 Oct.
Authors: Mourad Ahmedi, Sebastian Sitko, Carmen Mayolas-Pi
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11557728/pdf/cureus-0016-00000071395.pdf
Summary: Introduction Soccer is one of the most popular sports worldwide and is a leading physical activity choice among adolescents. This study aims to investigate how the competitive level of adolescent soccer players impacts their sleep quality and quality of life. Methods A total of 5,692 adolescents aged 11 to 19 years were classified based on their physical activity levels and competitive engagement. Participants were categorized as inactive, non-competitive athletes, or soccer players competing at local, regional, or national levels. An anonymous online questionnaire was used to assess sociodemographic characteristics, physical activity level, competition level, sleep quality, and quality of life. Significance was set at p < 0.05. The Chi-square (χ²) test was employed to examine frequency distributions. Comparisons based on competitive level were performed using Generalized Linear Models, adjusting for age, BMI, municipality size, and economic level. When significant differences were identified, post hoc analyses were conducted with a Bonferroni adjustment. Results Girls reported lower sleep quality and quality of life compared to boys. Soccer players exhibited better sleep quality and life satisfaction than inactive individuals and non-competitive athletes, independent of competitive level (p > 0.05 Bonferroni pairwise comparison). Among boys, regional-level soccer players showed the highest sleep quality and quality of life. For girls, national-level soccer players reported the best outcomes in both parameters. Conclusion Adolescent soccer players, regardless of their competitive level, demonstrate better sleep quality and quality of life than inactive individuals or non-competitive athletes. In general, higher levels of competition correlate with improved sleep quality and quality of life, particularly among female athletes.

13 Concomitant Popliteomeniscal Fascicles Tears Are Found in 21% of Professional Soccer Players With Acute Anterior Cruciate Ligament Injuries

Reference: Arthrosc Sports Med Rehabil. 2024 Jun 8;6(5):100956. doi: 10.1016/j.asmr.2024.100956. eCollection 2024 Oct.
Authors: Pier Paolo Mariani, Guglielmo Torre, Michael J Battaglia, Riccardo Ciatti, Rocco Papalia
Download link: https://arthroscopysportsmedicineandrehabilitation.org/action/showPdf?pii=S2666-061X%2824%2900074-9
Summary: The aim was to investigate the incidence of popliteomeniscal fascicles (PMF) tears in anterior cruciate ligament (ACL) rupture in professional soccer players, to describe arthroscopic and magnetic resonance imaging (MRI) findings and treatment of these lesions with clinical outcomes, and to evaluate the incidence of subsequent lateral meniscus tears and ACL reinjury. ACL reconstructions on soccer players were retrospectively analyzed, and among them, a cohort of patients with PMFs tears was reviewed. The cohort was assessed with MRI examination, arthrometric testing, Lysholm score, and International Knee Documentation Committee score. The occurrence of subsequent lateral meniscus tears and ACL reinjury were evaluated. A total of 208 ACL reconstructions were identified. From these, 43 male and 3 female subjects with a mean age of 24 ± 4.2 years were included. Median time from injury to surgery was 5 days. Preoperative MRI showed a tear of posterior PMFs in 24 of 47 knees (51.1%). The mean preoperative arthrometric measured laxity was 4.3 ± 1.65 mm, and postoperatively 0.1 ± 1.1 mm. Preoperative Lysholm score and International Knee Documentation Committee score were, respectively, 50.4 ± 25.4 and 39.6 ± 5, and postoperatively 98 ± 2.4 and 73.6 ± 1.2. Mean time to return to play, at the same preoperative level for all patients, was 184 ± 41.7 days. One patient underwent ACL revision due to a reinjury 9 months after surgery, whereas no lateral meniscus tears occurred in the follow-up period. PMF tears are found in approximately 20% of professional soccer players with acute ACL injuries. After ACL reconstruction and PMFs repair, outcomes including return to play are good, ACL retear is low, and recurrent lateral meniscus tears were not observed.

14 Consensus on maturity-related injury risks and prevention in youth soccer: A Delphi study

Reference: PLoS One. 2024 Nov 12;19(11):e0312568. doi: 10.1371/journal.pone.0312568. eCollection 2024.
Authors: Joseph Sullivan, Simon Roberts, Kevin Enright, Martin Littlewood, David Johnson, David Hartley
Download link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0312568
Summary: The aim of this study was to achieve consensus from leading sport and exercise science practitioners in professional soccer academies surrounding (i) motivations for maturity-related data collection (ii) maturity-related injury risk factors (iii) how maturity-related data informs injury prevention practices and (iv) the use of bio-banding as an alternative injury prevention strategy. The study adopted an iterative three round online Delphi method, where a series of statements were rated by expert panellists. Consensus agreement was set at ≥70% for all statements. Nine panellists participated in all three rounds (69% response rate). Consensus was achieved for a total of sixteen statements. Panellists agreed that the period during and 12-months post peak height velocity, muscle strength/flexibility imbalances and maturity status (% predicted adult height) as the most important maturity-related injury risk factors. Panellists also agreed that maturity-related data collection is important for injury prevention as well as physical and performance-related purposes, but not for recruitment or retain/release purposes. It was also evident that variability and misunderstanding of key language terms used within the growth and maturation literature exists. It was agreed that practitioners who are responsible for conducting maturational assessments require additional training/education to enhance their application, delivery and outcomes. The findings indicate that maturity-related data collection is part of a multidisciplinary process, dedicated towards the long-term development of players. Greater training and education are required along with increased dissemination of research findings surrounding the full uses for bio-banding. This study provides guidance on maturity-related injury risks and prevention in youth soccer for practitioners.

15 Pressing, pressure and re-aggressing as tactical movement of anterior cruciate ligament injuries in women’s soccer

Reference: J Sports Med Phys Fitness. 2024 Nov 11. doi: 10.23736/S0022-4707.24.16402-X. Online ahead of print.
Authors: Rosario D’Onofrio, Dario Pompa, Cristian Savoia, Matteo Masucci, Francesco Laterza, Vincenzo Manzi
Summary: A better understanding of anterior cruciate ligament (ACL) injury mechanisms in female soccer can guide better research on both prevention programs and late-stage rehabilitation for the return-to-sport process. This narrative review investigates the technical and tactical game situations in female soccer linked to ACL injury mechanisms. Through a literature search, we reviewed scientific literature to identify soccer-specific technical movements and tactical patterns that increase the risk of ACL injuries in female players. Articles were retrieved through Web of Science, SPORTDiscus, ScienceDirect, PubMed, and PubMed Central. Inclusion criteria were: 1) studies on ACL injury mechanisms in women’s soccer; 2) studies examining soccer techniques/tactics to identify non-contact injury mechanisms. Gray literature was included to supplement limited indexed data, aiming to stay within author guidelines. Female athletes experience a 2-8 times higher risk of ACL injury than males, with 70% of these injuries being non-contact. Common scenarios leading to these injuries involve ball possession/non-possession phases, tactical actions (pressing, pressure, re-aggression), and technical movements (cutting, changing direction). Tactical aspects, particularly pressing and re-aggression, are key contributors to ACL injury risk regardless of ball possession. In female soccer, ACL injuries are related to non-contact injury mechanisms during technical and tactical situations. The knowledge and study of these situational patterns of play, such as pressing, re-aggression, pressure, and cutting maneuvers, are essential to target prevention strategies and return-to-sport processes objectively.

16 Influence of Carbohydrate Intake on Different Parameters of Soccer Players‘ Performance: Systematic Review

Reference: Nutrients. 2024 Oct 31;16(21):3731. doi: 10.3390/nu16213731.
Authors: Marián Pueyo, Iñaki Llodio, Jesús Cámara, Daniel Castillo, Cristina Granados
Download link: https://www.mdpi.com/2072-6643/16/21/3731/pdf?version=1730874921
Summary: The objective of this systematic review is to analyze the influence of carbohydrate (CHO) intake on physical and technical aspects, glucose and muscle glycogen levels, fatigue, cognition, and gastrointestinal comfort involved in the performance of soccer players, as well as to examine whether there are any differences between men and women. A bibliographic search was conducted in PubMed, Web of Science, Scopus, and SportDiscus, resulting in 61 selected articles. The PRISMA recommendations and the Cochrane Handbook for Systematic Reviews guidelines were followed. The results indicate that CHO intake before and during the match improves speed and the number of sprints, attenuates the decrease in shooting accuracy and speed, increases time to fatigue, and enhances cognitive function. There is no consensus on passing, dribbling, jumping, or agility improvements. Glucose levels drop during the first 15 min of the second half without affecting performance. It is recommended that players ingest 6-8 g/kg/d of CHO the day before, a meal with 1-3 g/kg 3-4 h before, and 30-60 g/h during the match. Muscle glycogen drops drastically at the end of the match, remaining low at 48 h. Hence, 1-1.5 g/kg/h is recommended during the first 4 h, starting from the first 20 min. Female soccer players have a similar physical demand to men, and energy availability is low, especially in the post-match periods, as they underestimate their energy expenditure and do not consume enough CHO. Therefore, the recommended guidelines should be followed, individualized, and periodized according to each athlete’s energy needs.

17 Influence of Training Load on Muscle Contractile Properties in Semi-Professional Female Soccer Players Across a Competitive Microcycle: A Pilot Study

Reference: Sensors (Basel). 2024 Oct 30;24(21):6996. doi: 10.3390/s24216996.
Authors: Ezequiel Rey, María Lois-Abal, Alexis Padrón-Cabo, Miguel Lorenzo-Martínez, Pablo B Costa
Download link: https://www.mdpi.com/1424-8220/24/21/6996/pdf?version=1730365831
Summary: This study aimed to evaluate changes in muscle contractile properties during a training microcycle in semi-professional female football players and explore their relationship with training load variables. Nineteen players (age: 23.9 ± 3.9 years; body mass: 60.6 ± 6.9 kg; height: 164.5 ± 6.7 cm) underwent myotonometric assessments of the biceps femoris (BF) and rectus femoris (RF) before and after the following training sessions: MD1 (i.e., 1 day after the match), MD3, MD4, and MD5. Training loads were quantified for each session, revealing significant variations, with MD4 exhibiting the highest values for high-speed running distance, number of sprints, and accelerations. Notably, MD3 showed the highest perceived exertion (RPE), while MD5 recorded the lowest total distance run. Myotonometric assessments indicated significant differences in stiffness of the RF in MD3 and BF in MD5, as well as RF tone in MD5. The findings underscore a notable relationship between training load and myotometric variables, particularly in muscle stiffness and tone. These results emphasize the need for further research to clarify how training loads affect muscle properties in female athletes.

18 Instrument for Evaluation and Training of Decision Making in Dual Tasks in Soccer: Validation and Application

Reference: Sensors (Basel). 2024 Oct 24;24(21):6840. doi: 10.3390/s24216840.
Authors: Lucas Romano Oliveira de Souza, Alexandre Luiz Gonçalves de Rezende, Jake do Carmo
Download link: https://www.mdpi.com/1424-8220/24/21/6840/pdf?version=1729839682
Summary: Training in team sports such as soccer requires advanced technical and tactical skills for effective decision-making, particularly when executing a shot. This study validates an innovative instrument, a training platform (TP), designed to measure and enhance decision-making in dual-task scenarios. The TP aims to improve visual-motor reactions in multitask environments that simulate real game conditions. Equipped with an LED panel, main circuitry, ball sensor, and targets, the TP challenges players to kick the ball in response to the illumination of the final LED array on the panel while hitting a designated target. The study evaluated three parameters: reaction time (RT), ball speed (BS) and accuracy. To validate the TP against a gold standard (GS), we conducted correlation analyses. The results exhibited very strong correlations for both RT (r = 0.997) and BS (r = 0.994). The mean differences between TP and GS measurements were 13 ± 15 ms for RT and 0.1 ± 0.5 km/h for BS. Bland-Altman plots revealed trend lines obtained by a simple linear regression of r = -0.507, p = 0.307 for RT and r = 0.134, p = 0.077 for BS. The TP effectively simulates game scenarios, offering advantages such as low-cost components, installation flexibility, test variability, instant feedback, and integration of physical and cognitive components of sports performance.

19 Perceptual Health and Wellbeing, Self-Reported Sleep, and Hydration Status in Youth Soccer Players During Competition

Reference: J Nutr Metab. 2024 Oct 30:2024:5086660. doi: 10.1155/2024/5086660. eCollection 2024.
Authors: Michael King, Rachel Kimble, Matthew Brown, Seamus McCafferty, Hannah Lithgow
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11540896/pdf/JNME2024-5086660.pdf
Summary: The aim of this study was to assess match time courses on hydration, wellness, and sleep as well as the interrelationship between these variables in youth national soccer players.  Under-17 and under-19 youth national soccer players (age range: 16.96 ± 1.17 years) completed a perceptual wellness questionnaire, self-reported their sleep, and carried out hydration assessments each morning during a period of competitive match play. Players reported having significantly more sleep leading into the day of a match (MD) compared to both the evening after a match (MD-2; p < 0.001; CI = 7.972 and 8.212) and the evening before a match (MD-1; p < 0.001; CI = 7.996 and 8.174). Furthermore, players reported better health and wellbeing scores on MD compared to both MD-1 (p < 0.001; CI = 19.231 and 19.692) and MD-2 (p < 0.001; CI = 18.911 and 19.489). When self-reported sleep was correlated with the individual components of health and wellbeing, it was highlighted that there were significant effects for fatigue (r = 0.304, p < 0.001; CI = 0.250 and 0.383), mood (r = 0.170, p < 0.001; CI = 0.112 and 0.243), general muscle soreness (r = 0.225, p < 0.001; CI = 0.162 and 0.306), and stress (r = 0.203, p < 0.001; CI = 0.147 and 0.274).  It is important to consider sleep strategies to mitigate the potential impact of lack of sleep following match play. Self-reported sleep seems to be appropriate for estimating individual components of health and wellbeing, and therefore may be a suitable replacement for perceptual wellness questionnaires.

20 Anthropometric and mechanical factors determining sprint in young soccer players: a brief report

Reference: Front Sports Act Living. 2024 Oct 24:6:1480973. doi: 10.3389/fspor.2024.1480973. eCollection 2024.
Authors: Alejandro Bustamante-Garrido, Esteban Aedo-Muñoz, Ciro Brito, Danilo Silva-Esparza, Jorge Pérez-Contreras, Mikel Izquierdo-Redin, Hugo Cerda-Kohler
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11540635/pdf/fspor-06-1480973.pdf
Summary: Sprint performance is a critical factor in soccer. While previous studies have extensively explored the biomechanical, physiological, and metabolic determinants of sprinting, the impact of anthropometric variables in team sports contexts, especially soccer, remains underexplored. This study aims to investigate the influence of anthropometric and mechanical variables on sprint performance in young soccer players. Fifty-eight young soccer players were evaluated in anthropometry and a 30-meter (m) sprint using radar technology. Split times in 5, 15, and 30 m were determined, in addition to the assessment of the force-velocity profile proposed by Morin and Samozino. Results: Key anthropometric variables associated with improved sprint performance included lower-limb muscle mass at distances 5 and 15 m (R 2 = 0.08 and R 2 = 0.09, respectively, both with small effects). Additionally, body composition, particularly a lower % body fat, was crucial across all sprint distances (ES: large). Among the mechanical variables, max power (R 2 = 0.997, ES: large) and maximum velocity (R 2 = 0.553, ES: large) are the mechanical variables that were most strongly associated with sprint performance over distances greater than 30 m. Soccer coaches, athletic trainers, and strength and conditioning specialists working with young athletes can apply the findings of this study to their training programming.

21 Enhancing Sprint Performance and Biomechanics in Semiprofessional Football Players Through Repeated-Sprint Training

Reference: J Appl Biomech. 2024 Nov 15:1-9. doi: 10.1123/jab.2024-0026. Online ahead of print.
Authors: Valentin Romero, Adrián Castaño-Zambudio, Manuel Alejandro Ortega-Becerra, Juan Antonio Vázquez-Diz, Juan Jesús Adalid-Leiva, Pedro Jiménez-Reyes
Summary: Repeated-sprint ability is a significant factor in football performance. Notably, hamstring injuries in football players often occur during sprinting activities and fatigue-inducing conditions. Therefore, the aim of this study was to examine the impact of repeated-sprint training (RST) on repeated-sprint ability variables and sprint kinematics. Fourteen semiprofessional men’s soccer players performed 8 weeks of RST, consisting of 1 to 2 sets of 5 to 8 × 30 m repeated sprints separated by 20 to 30 seconds of recovery. Sprint performance was computed from running speed data, and a high-frequency camera (240 Hz) was used to study kinematic data. Paired samples t test and repeated-measures analysis of variance were conducted for each performance and kinematic variable, respectively. After the RST period, moderate to large improvements were observed for 0 to 20 m time, 0 to 30 m time, and 20 to 30 m time. All the repeated-sprint ability-related variables were significantly improved (P < .05). In addition, during fatigue conditions, a decrease in trunk flexion and kick-back mechanism and a reduced overstriding pattern was found after RST. The findings of this study suggest that incorporating RST may lead to improved sprint performance and promote a „safer“ sprint pattern, particularly during periods of fatigue.

22 Illness, the overlooked research topic for time-loss in women’s football – a scoping review

Reference: Res Sports Med. 2024 Nov 15:1-12. doi: 10.1080/15438627.2024.2428603. Online ahead of print.
Authors: Albert Wang, Bethany Koh, Alan McCall, Eva Ferrer, Ritan Mehta, Katrine Okholm Kryger
Summary: The best medical care for female football athletes should be evidence-based, and patient- and context-specific. A 2019 scoping review identified key knowledge gaps relating to the health of female footballers. Since then, research in women’s football has been intensifying. To aid in the direction of future research, this study aims to scope peer-reviewed, illness-related research in women’s football. Five databases were searched in July 2023. In combination with identified studies from the 2019 review, 72 studies were included for data extraction of sample characteristics (age, playing level, geography), illness characteristics according to IOC guidance, and broader research themes. Results reveal an overall lack of quantity and variety in illnesses investigated, with a growing popularity in mental health research. Minimal female athlete-specific illnesses were identified. Future research must address urgent female-specific illness topics, and also consider where knowledge from adjacent populations might be safe to adapt into women’s football.

23 Sex-based differences in hamstrings stiffness assessment in football players using ultrasound shear wave elastography

Reference: Quant Imaging Med Surg. 2024 Nov 1;14(11):7839-7847. doi: 10.21037/qims-24-398. Epub 2024 Oct 24.
Authors: Beatriz Alvarez de Sierra Garcia, Diana Expósito Jimenez
Summary: Hamstring stiffness varies among individuals and can influence athletic performance and injury risk. Sex-based differences in hamstring stiffness among football players have not been thoroughly investigated. This study aimed to assess these differences using shear wave elastography (SWE), a non-invasive ultrasound technique that quantifies tissue stiffness. The study recruited 30 football players (15 male, 15 female) in June 2022 during their annual medical check-up. Participants were aged 18-40 years, engaged in regular training, and had no history of lower limb musculoskeletal injury in the six weeks preceding the study. SWE was used to measure shear wave velocity (SWV) in the hamstring muscles: semitendinosus (ST), semimembranosus (SM), and biceps femoris (BF). Independent t-tests were used to compare the SWV values of the hamstring muscles between sexes and between dominant and non-dominant legs. ST muscle had a statistically significant difference in SWV based on gender and leg dominance with marked differences particularly in the non-dominant leg across both genders (P=0.02; Bonferroni corrected P=0.05). SWV for ST in male group was significantly higher than that in female group; the mean elasticity of the male group for dominant and non-dominant leg were 3.8±1.5 and 4.1±1.2 m/s, respectively; and the mean elasticity of the female group for dominant and non-dominant leg were 2.9±0.7 and 2.8±0.7 m/s respectively. In contrast, SWV differences in the SM and BF muscles were not statistically significant (P=0.187 and 0.760, respectively). The study revealed significant sex-based differences in hamstring stiffness among football players, as assessed by SWE. ST muscle stiffness was associated with higher SWV in male group and show stronger correlation with non-dominance leg. These findings can contribute to individualized training programs and injury prevention strategies.

24 Menstrual cycle performance barriers experienced by elite women football players and their management strategies applied: A semi-structured interview-based study

Reference: Sci Med Footb. 2024 Nov 14:1-7. doi: 10.1080/24733938.2024.2425291. Online ahead of print.
Authors: Phoebe Read, Craig Rosenbloom, Ritan Mehta, Hannah Owen, Elena Jobson, Katrine Okholm Kryger
Summary: The objective of this study was to investigate the barriers experienced by elite women football players due to their menstrual cycle, and coping strategies utilised against these barriers. Fifteen elite women footballers from two English Women’s Super League clubs (age: 25.2 years [18-33]) were interviewed using semi-structured interviews, developed using piloting and peer review. Data was audio recorded, transcribed verbatim and analysed thematically using NVivo. Analysis of 27,438 words unveiled key themes: internal barriers, external barriers, coping strategies, and player needs. Fear of leakage, associated with kit colour (n = 15) and lack of effective sanitary products (n = 12), and injury anxiety (n = 7), associated with ACL injury (n = 5), were the most common barriers. To combat these issues, players use internal (feeling fortunate n = 9) and external (support from teammates n = 6; support from club staff n = 4) coping strategies. The findings indicated that menstruation presents significant barriers to players. Increased awareness of menstruation-related barriers to performance and targeted intervention are achievable through staff and player involvement and by minimising concerns of visible leakage by kit interventions.

25 Achilles Tendon Pain in Male Professional Football Players – A Prospective Five-Season Study of 88 Injuries from the UEFA Elite Club Injury Study

Reference: Open Access J Sports Med. 2024 Nov 9:15:171-179. doi: 10.2147/OAJSM.S493843. eCollection 2024.
Authors: Markus Waldén, Mariann Gajhede Knudsen, Jan Ekstrand, Martin Hägglund, Pieter D’Hooghe, Håkan Alfredson, Håkan Bengtsson
Download link: https://www.dovepress.com/article/download/97170
Summary: The objective was to describe the location, examination procedures, diagnoses, and treatment for gradual-onset Achilles tendon pain in male professional football (soccer) players. Forty-seven teams were followed prospectively for at least one season from 2013/14 to 2017/18. Time-loss injuries were recorded by the teams‘ medical staffs. For all non-contact Achilles tendon injuries, a specific Achilles tendon form was sent to teams. There were 88 time-loss injuries recorded with gradual-onset Achilles tendon pain amongst 72 players; 22 (25%) of them were severe lasting more than four weeks including one career-ending injury. The specific form was returned for 78 injuries (89%) with 55 cases (71%) having midportion and 23 cases (29%) insertional pain. There were 51 cases (65%) being examined with ultrasound and 29 cases (37%) with magnetic resonance imaging, both modalities being used in 18 cases (23%). Tendinopathy was the most frequently reported main diagnosis both for midportion and insertional pain with 60 cases (77%), but multiple diagnoses were recorded in 21 cases (27%). Surgery was performed in six cases (8%), and the majority of players were exposed to several non-surgical treatments in various combinations, with eccentric training and cryotherapy being most frequent with 52 cases (72%) each. Tendinopathy was the most frequent diagnosis both for midportion and insertional pain. Imaging was carried out for most injuries. A majority of injuries were managed non-surgically, with eccentric training and cryotherapy being the most frequently applied treatments.

26 Classification of recovery states in U15, U17, and U19 sub-elite football players: a machine learning approach

Reference: Front Psychol. 2024 Oct 29:15:1447968. doi: 10.3389/fpsyg.2024.1447968. eCollection 2024.
Authors: José E Teixeira, Samuel Encarnação, Luís Branquinho, Ricardo Ferraz, Daniel L Portella, Diogo Monteiro, Ryland Morgans, Tiago M Barbosa, António M Monteiro, Pedro Forte
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11554510/pdf/fpsyg-15-1447968.pdf
Summary: A promising approach to optimizing recovery in youth football has been the use of machine learning (ML) models to predict recovery states and prevent mental fatigue. This research investigates the application of ML models in classifying male young football players aged under (U)15, U17, and U19 according to their recovery state. Weekly training load data were systematically monitored across three age groups throughout the initial month of the 2019-2020 competitive season, covering 18 training sessions and 120 observation instances. Outfield players were tracked using portable 18-Hz global positioning system (GPS) devices, while heart rate (HR) was measured using 1 Hz telemetry HR bands. The rating of perceived exertion (RPE 6-20) and total quality recovery (TQR 6-20) scores were employed to evaluate perceived exertion, internal training load, and recovery state, respectively. Data preprocessing involved handling missing values, normalization, and feature selection using correlation coefficients and a random forest (RF) classifier. Five ML algorithms [K-nearest neighbors (KNN), extreme gradient boosting (XGBoost), support vector machine (SVM), RF, and decision tree (DT)] were assessed for classification performance. The K-fold method was employed to cross-validate the ML outputs. A high accuracy for this ML classification model (73-100%) was verified. The feature selection highlighted critical variables, and we implemented the ML algorithms considering a panel of 9 variables (U15, U19, body mass, accelerations, decelerations, training weeks, sprint distance, and RPE). These features were included according to their percentage of importance (3-18%). The results were cross-validated with good accuracy across 5-fold (79%). The five ML models, in combination with weekly data, demonstrated the efficacy of wearable device-collected features as an efficient combination in predicting football players‘ recovery states.

27 Acute responses to a potentiation warm-up protocol on sprint and change of direction in female football players: a randomized controlled study

Reference: BMC Sports Sci Med Rehabil. 2024 Nov 12;16(1):230. doi: 10.1186/s13102-024-01015-z.
Authors: Tomás Zylberberg, Ricardo Martins, Svein Arne Pettersen, José Afonso, Ivan André Matias Vale Baptista
Download link: https://bmcsportsscimedrehabil.biomedcentral.com/counter/pdf/10.1186/s13102-024-01015-z.pdf
Summary: The aim was to evaluate the acute effect of exposure to a potentiation warm-up protocol compared to a usual warm-up program. Seventeen female football players (age: 23.9 ± 3.9 years), were randomly allocated to a control (n = 8) and an experimental group (n = 9). To allocate the players, a table was computer-generated by a research team member with no involvement in the trial. The control group performed their usual warm-up program, while the experimental group performed a potentiation warm-up protocol with jumps combined with sprints with change of direction. The players were tested pre- and post-intervention for a 40-m linear sprint and pre-planned change of direction using the T-test. An intention-to-treat analysis was performed, with all the participants originally randomized being involved. The normal distribution was verified by the Shapiro-Wilk test. The assumption of sphericity was analyzed. Effect sizes were calculated using partial eta squared. No significant pre-post differences in the T-test and in the 40-m sprint were detected for any group. However, in the T-test, large effect sizes in time increments were observed within the experimental (0.27 s; p > 0.05, ηp2 = 0.176) and control groups (0.06 s; p > 0.05, ηp2 = 0.176). Also, in the 40-m sprint, large effect sizes in time increments were observed within the experimental (0.05 s; p > 0.05, ηp2 = 0.251) and control groups (0.09 s; p > 0.05, ηp2 = 0.251). The performance-enhancing ability of the potentiation method performed at warm-up was not verified when applied to female football players. Thus, the potentiation methods may not improve sprint and COD ability for this population. However, the lack of statistical significance may have been due to reduced statistical power, as three of four effects suggest acute performance impairment after a supposed potentiation-oriented warm-up. Nevertheless, the presence of a statistical type 2 error cannot be ruled out.

28 Performance variables and nutritional status analysis from Moroccan professional and adolescent football players during the competition period: a descriptive study

Reference: Front Sports Act Living. 2024 Oct 28:6:1372381. doi: 10.3389/fspor.2024.1372381. eCollection 2024.
Authors: Mourad Oukheda, Halima Lebrazi, Abdelfettah Derouiche, Anass Kettani, Rachid Saile, Hassan Taki
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11550936/pdf/fspor-06-1372381.pdf
Summary: Nutrition plays an integral role in optimizing football players‘ performance during training sessions and matches and maintaining their overall health throughout the season. This study aimed to evaluate how well the dietary practices of professional and adolescent football players in Morocco during the competitive period met international macronutrient recommendations, and to explore the relationship between their nutritional status and aerobic performance, as measured by the Yo-Yo IRL1 test. A total of 277 footballers from Morocco’s professional league, „Botola-Pro“, were monitored over a seven-day (training microcycle) during the competitive period. The dietary intake was assessed through self-reported methods and 24-hour recalls. Relevant body composition was measured with bioelectrical impedance (BI), and aerobic performance was evaluated using the Yo-Yo IR test. The results indicated significant variations in performance and nutritional status across different categories and age groups. The nutritional status of the players didn’t match the UEFA recommendations (p < 0.001). We found that higher intake levels of carbohydrates and proteins were positively correlated with the total distance covered by the players (p < 0.001, r = 0.63, R2 = 0.4 for carbohydrates; p < 0.001, r = 0.59, R2 = 0.35 for proteins). Conversely, a higher proportion of energy derived from fats in the diet was negatively correlated with the distance covered (p < 0.001, r = -0.64, R2 = 0.41). These findings suggest that optimizing carbohydrates and protein intake while managing fat consumption is crucial for enhancing sporting performance. This information is essential for tailoring training programs and nutritional regimens based on the competition level.

29 Detrimental Industries‘ Sponsorship in Football Clubs Across Ten Major Leagues from 2000-2022: A Retrospective Study

Reference: Nutrients. 2024 Oct 24;16(21):3606. doi: 10.3390/nu16213606.
Authors: Mikołaj Kamiński, Wiktor Szymajda, Ada Kaczmarek, Matylda Kręgielska-Narożna, Paweł Bogdański
Download link: https://www.mdpi.com/2072-6643/16/21/3606
Summary: Sponsorship of football teams by detrimental industries may negatively impact fans‘ dietary and behavioral choices. The study aimed to determine the proportion of sponsors on the jerseys of teams in the top ten football leagues that comprise companies producing alcohol or unhealthy food, or engaging in gambling. We conducted a retrospective study, incorporating data from first-division football teams in 10 countries (Argentina, Brazil, England, France, Germany, Italy, Poland, the Netherlands, Spain, and the United States) playing from 2000-2022. Data were collected on the primary sponsors displayed on team jerseys and categorized into alcohol, unhealthy food (defined as producers of ultra-processed food according to the NOVA classification), gambling, or other, based on the nature of the products or services offered by the sponsors. We performed descriptive statistical analyses and multivariate linear regression analyses. A total of 4452 sponsorship records were analyzed. The majority were classified as „other“ (81.8%), followed by gambling (6.9%), alcohol (2.6%), and unhealthy food (2.6%). We did not identify any sponsor representing the tobacco industry. The prevalence of gambling sponsors surged from 1.7% in 2000 to 16.3% in 2022. Conversely, alcohol-related sponsorships dwindled from 6.2% in 2000 to 1.0% in 2022. In the multivariate linear regression model, these trends were statistically significant. The alcohol industry remained visible in the Spanish league. A significant proportion of sponsorships on the jerseys of top football teams across the world represents alcohol, ultra-processed food, or the gambling industry. Trends in the types of sponsors on the jerseys of leading football clubs across the Western world are diverse. Particularly concerning is the recent increase in the percentage of clubs sponsored by the gambling industry. To limit the detrimental effects of the promotion of unhealthy products, novel policies should be considered.

30 The Impact of a Congested Match Schedule (Due to the COVID-19 Lockdown) on Creatine Kinase (CK) in Elite Football Players Using GPS Tracking Technology

Reference: Sensors (Basel). 2024 Oct 28;24(21):6917. doi: 10.3390/s24216917.
Authors: Jorge Garcia-Unanue, Antonio Hernandez-Martin, David Viejo-Romero, Samuel Manzano-Carrasco, Javier Sanchez-Sanchez, Leonor Gallardo, Jose Luis Felipe
Download link: https://www.mdpi.com/1424-8220/24/21/6917
Summary: The aim was to analyse the consequences of a congested schedule (due to the COVID-19 lockdown) on creatine kinase (CK) in elite football players using GPS tracking technology. A total of 17 elite football players were monitored in training and competition with a global positioning system. Variables including total distance, high-intensity distance, and distance acceleration and deceleration were analysed. Different measurements of serum creatine kinase (CK) concentration were performed on match day (MD) and at 24 h (MD+1), 48 h (MD+2), and 72 h (MD+3) after each match to study the muscle damage of each individual player caused during the match. The results showed a significant increase in physical demands in training (in relative terms regarding the match) at MD+3 compared to MD+1 and MD+2. Furthermore, at +72 h, CK decreases to a value almost the same as that before MD. On the other hand, the players with lower demands for high-intensity actions in the match showed a higher reduction in the concentration of CK at MD+3 compared to MD+1 and MD+2 (p < 0.05). It became evident that players with high-intensity demand and a high number of accelerations and decelerations need more time to assimilate the match load and can remain in a state of muscle fatigue for up to 3 days. In addition, a congested schedule can lead to a state of chronic fatigue in elite football players, limiting physical performance and possibly increasing the potential risk of injury for football players.

31 Forecasting extremes of football players‘ performance in matches

Reference: Sci Rep. 2024 Nov 9;14(1):27319. doi: 10.1038/s41598-024-78708-5.
Authors: Michał Nowak, Bartosz Bok, Artur Wilczek, Łukasz Oleksy, Mariusz Kamola
Download link: https://www.nature.com/articles/s41598-024-78708-5.pdf
Summary: This study evaluates the use of simple linear or piecewise linear predictive models to predict extreme performance metrics in soccer matches, based on historical training and to match data of soccer players from RKS Raków Częstochowa football club. The data were collected from January to June 2023. The collected training and matched data average is 9000 records per month. A standard workweek at the RKS Academy consisted of 5 training units and at least 1 match. The best individual models found predict selected game performance metrics with a relative error of 2.3%, suggesting an excellent model fit between prediction and the actual value. This is illustrated by input data metric called „Metabolic Time Zone 5 and 6 Per Distance“, and output data by „Decelarations Total Distance in Zone 5 and 6 Per Distance“-calculated for in 3 min sliding window and characterized by the highest value of the generated parameter based on High Metabolic Load Distance (HMLD). The result concerns models run on aggregated performance metrics developed in APEX-PRO system using expert knowledge in soccer training, while raw GPS location-based models performing worse but still acceptably. Although we believe that the accuracy of the models still has limited reliability, their clarity and up-to-date quality make them useful in the daily planning of training activities and the management of workloads that affect player performance in the upcoming match, as well as the tactical decisions of the coach. More accurate predictions are given by individual models compared to aggregated models (player position), but there are exceptions where group models also perform very well. Adding a second metric to the input did not show a significant difference in the analyzed examples (the results are very similar). Our findings indicate that the model based on metrics from the last match also effectively predict extreme motor performances occurring in the game. In the case of the analyzed player, it was at the input „Accelerations Total Time Per Distance in Zone 6“ at the output „Distance in Zone 6“. Specific training or match parameters can be key in predicting exceptional soccer performance, but they can also vary depending on the analyzed player. This confirms the need for further analysis of this issue.

32 Changes in female football players‘ in-season training load, intensity and physical performance: training progression matters more than accumulated load

Reference: Front Sports Act Living. 2024 Oct 24:6:1454519. doi: 10.3389/fspor.2024.1454519. eCollection 2024.
Authors: Eero H J Savolainen, Johanna K Ihalainen, Tomi Vänttinen, Simon Walker
Download link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11540696/pdf/fspor-06-1454519.pdf
Summary: This observational study investigated: (1) potential changes in female football players‘ in-season training load, intensity and physical performance, and (2) if in-season accumulated training load, intensity, or their progression are associated to changes in physical performance. Thirty-five national level female players (∼21 years, n = 35) from three top-teams of the Finnish national league participated. Players performed tests at the beginning and at the end of the 27-week in-season. Tests were: 30-m sprint, countermovement jump (CMJ) and 1,200-m shuttle run, used to calculate maximal aerobic speed (MAS). Players‘ external and internal training load and intensity were monitored in all on-field training sessions and official matches (3,941 data samples) using Polar Team Pro system. Training load decreased towards the end of the in-season (p < 0.05), but intensity remained stable. No changes in physical performance test results occurred from before to after in-season tests at a group level. Change of CMJ correlated negatively with accumulated training load, intensity and progression of total distance (TD) and low-intensity running distance (LIRD) (r = -0.398 to -0.599, p < 0.05). Instead, development of MAS correlated positively with progression of TD and LIRD intensities (r = 0.594 and 0.503, p < 0.05). Development of both CMJ and MAS correlated positively with intensity progression of very-high-intensity running distance (VHIRD) and number of accelerations and decelerations (r = 0.454-0.588, p < 0.05). Reduced training load over the in-season is not detrimental for players‘ physical performance when training intensity progressively increases. Intensity progression of VHIRD, moderate- and high-intensity accelerations and decelerations are indicators of both MAS and CMJ development, respectively.