Latest research in football - week 11 - 2023

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 How are hamstring strain injuries managed in elite men's football clubs? A survey with 62 Brazilian physical therapists

Reference: Phys Ther Sport. 2023 Mar 4;61:73-81. doi: 10.1016/j.ptsp.2023.03.001. Online ahead of print.

Authors: Henrique Gonçalves Valente, Rodrigo Ribeiro de Oliveira, Bruno Manfredini Baroni

Summary: The aim was to describe perceptions and practices of physical therapists from elite men's football clubs on the management of athletes with hamstring strain injury (HSI). Physical therapists from clubs engaged in the two main divisions of Brazilian men's football. Practices for assessment and rehabilitation of athletes with HIS were used as main outcome measures. This survey had 62 physical therapists from 35 of the 40 eligible clubs (87.5% representativeness). Despite heterogeneity on assessment practices, all respondents use imaging exams, adopt injury classification scales, and evaluate aspects related to pain, range of motion, muscle strength, and functional status of athletes with HSI. Rehabilitation programs are usually divided into 3 to 4 phases. All respondents usually apply electrophysical agents and stretching in HSI rehabilitation programs, 98.4% apply strengthening exercises (93.5% include eccentrics), 96.8% manual therapy, 95.2% exercises that mimic the functional demands of football, and 93.5% lumbopelvic stabilization exercises. Muscle strength was the most reported return to play criterion (71% of respondents). The present study allowed the sports physical therapy community to become aware of the approaches usually adopted for management of athletes with HSI who play in the highest level of Brazilian men's football.



#2 Former participation in professional football as an occupation in patients with isolated REM sleep behavior disorder leading to a synucleinopathy: a case-control study

Reference: J Neurol. 2023 Mar 20. doi: 10.1007/s00415-023-11591-8. Online ahead of print.

Authors: Alejandra Collía, Alex Iranzo, Mónica Serradell, Amaia Muñoz-Lopetegi, Gerard Mayà, Joan Santamaría, Raquel Sánchez-Valle, Carles Gaig

Summary: Contact sports such as football are associated with late development of neurodegenerative diseases, in part due to the deleterious effect of repetitive head impacts during participation. Isolated REM sleep behavior disorder (IRBD) represents an early manifestation of neurodegenerative diseases including Parkinson disease (RBD) and dementia with Lewy bodies (DLB). We hypothesized that former professional football participation would be overrepresented in IRBD. The aim was o assess former participation in professional football as an occupation in IRBD. In a case-control retrospective study, having played football as a professional occupation in the Spanish Football Professional Leagues was examined interviewing polysomnographically confirmed IRBD patients and matched controls without IRBD. Among 228 Caucasian Spanish IRBD patients with 68.5 ± 7.2 years, six (2.63%) were retired professional footballers. Length professional football career ranged between 11 and 16 years. Interval between football retirement and IRBD diagnosis was 39.5 ± 6.4 years. At IRBD diagnosis, the six footballers had synucleinopathy biomarkers including pathologic synuclein in the CSF and tissues, nigrostriatal dopaminergic deficit and hyposmia. Follow-up showed that three footballers developed PD and two DLB. None of the controls was a professional footballer. The percentage of professional footballers was higher in IRBD patients than in controls (2.63% versus 0.00%; p = 0.030) and among the general Spanish population (2.63% versus 0.62%; p < 0.0001). We found an overrepresentation of former professional footballers in IRBD patients who later developed PD and DLB after four decades from professional retirement. In professional footballers the development of a neurodegenerative disease may be first manifested by IRBD. Screening for IRBD in former footballers might identify individuals with underlying synucleinopathies. Further studies with larger samples are needed to confirm our observations.



#3 The Effect of cam and pincer morphology on hamstring injury rates and return to play in elite young male football players

Reference: Acta Orthop Traumatol Turc. 2023 Jan;57(1):36-39. doi: 10.5152/j.aott.2023.22115.

Authors: Engin Dinç, Serdar Arslan, Mahsum Akıkol

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Summary: This study aimed to determine the effects of cam and pincer morphology on the hamstring injury rate, treatment duration, and recurrence number of elite young male football players. Seventy-five elite young male football players were included in this study. Participants were evaluated physically and radiologically for femoroacetabular impingement during pre-season or pre-transfer routine health examinations. Athletes' injury and treatment data for 6 seasons were then collected prospectively and evaluated retrospectively. Athletes were divided into 2 groups: patients with cam and pincer morphology (group 1) and those without (group 2). Both groups were compared regarding the number of hamstring injuries, treatment duration, and recurrence numbers. The mean age was 20.35 ± 1.37 in group 1 (n = 23) and 18.92 ± 1.48 in group 2 (n = 52). There was a significant difference between the 2 groups regarding age and body weight. The rate of hamstring injuries in group 1 was higher than in group 2, and this difference was statistically significant. Although the recurrence rate (group 1-35.7%, group 2-27.8%) and treatment duration (group 1: 18.4 ± 10.1 days, group 2: 12.1 ± 6.2) in group 1 were higher than in group 2, there was no statistical significance between 2 groups. The present study has shown that hamstring injuries are more common in elite young male football players with cam and pincer morphology than those without. Therefore, further studies of musculoskeletal dysfunctions of femoroacetabular origin should be considered in the programs prepared to prevent and treat hamstring injuries.



#4 Maximum proportion of masks worn: Collaborative efforts in Japanese professional football

Reference: J Infect Public Health. 2023 Mar 15;S1876-0341(23)00090-4. doi: 10.1016/j.jiph.2023.03.009.

Authors: Tetsuo Yasutaka, Masaki Onishi, Wataru Naito, Yoshiaki Bando, Tomoaki Okuda, Michio Murakami

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Summary: Mass gathering events in Japan have gradually mitigated their novel coronavirus disease (COVID-19) control regulations, along with a minimum infection risk. The Japan Professional Football League (J.League) conducted pilot surveys on holding events with chant cheers. In this commentary, we introduce the collaborative efforts based on scientific knowledge among experts, J.League, and their fans. We performed risk assessment in advance, by updating a previously developed model. We further observed the average proportion of masks worn, chant cheering time of participants, and CO2 levels in the stand. The number of new COVID-19 cases in an event with 5,000 chant cheering participants and 35,000 non-chant cheering participants was estimated to be 1.02 times of an event, with 40,000 non-chant cheering participants. The average proportion of masks worn during the game was 98.9 %, for chant cheer participants. The chant cheering participants spent 50.0-51.1 % of their time chant cheering. Monitored average CO2 levels were ≤ 540 ppm, suggesting high ventilation rates in the stand. The high proportion of masks worn represents the willingness of norm-conscious fans to cooperate in regular recovery of the sport. This has proved to be one of the successful models for future mass gathering events.



#5 Patellofemoral Pain, Q-Angle, and Performance in Female Chinese Collegiate Soccer Players

Reference: Medicina (Kaunas). 2023 Mar 16;59(3):589. doi: 10.3390/medicina59030589.

Authors: Songhui You, Yinhao Shen, Qingguang Liu, Antonio Cicchella

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Summary: Female sports injuries have been neglected by science, and few relevant studies have considered female subjects. Knee pain in female soccer players is more common than in male soccer players. The number of days of absence from training and competition has been shown to be higher in females than males. The reporting of knee pain is common in female soccer players, but whether knee pain is associated with morphological features is unclear. The Q-angle of the knee has been hypothesized to be a causal factor in knee pain. Asian females have shown higher levels of valgus than non-sporting Caucasian populations, but no data exist for female Chinese players. The aim of our study was to investigate whether there are associations between knee pain, the Q-angle of the lower limb, jump performance, play time, and perceived exertion in female Chinese collegiate soccer players. We measured the Q-angle, patellofemoral/anterior knee pain (SNAPPS questionnaire), and CMJ and SJ performance of 21 subjects (age: 20.09 ± 1.13 years, weight: 56.9 ± 6.26 kg, height: 164.24 ± 4.48 cm, and >10 years of practice) before and after a match; Borg scale and play time results were also recorded. We found that our studied group had higher Q-angles in comparison to other ethnic groups reported in the literature, as well as an association of the Q-angle with the age, height, and weight of the players; however, contrary to other studies, we did not find any association between the Q-angle and knee pain, jumps, play time, or perceived exertion. Knee pain was not associated with any of the measured variables. Female Chinese soccer players showed higher Q-angles than players of other ethnic groups, a result that was associated with anthropometrics. The Q-angle was not found to be associated with knee pain, for which the sole determinant was body height.



#6 A Soccer Shot with Lengthy Consequences-Case Report & Current Literature Review of Commotio Cordis

Reference: J Clin Med. 2023 Mar 16;12(6):2323. doi: 10.3390/jcm12062323.

Authors: Philipp Spitaler, Markus Stühlinger, Agne Adukauskaite, Axel Bauer, Wolfgang Dichtl

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Summary: Commotio cordis, caused by objects being directly delivered to the chest, may cause cardiac arrest in young athletes, even without identifiable structural damage to the sternum, ribs or heart itself. Its prevention and management often remain suboptimal, resulting in dismal outcomes.  A 32-year semi-professional goalkeeper suffered from a non-penetrating blunt thoracic trauma after being struck by a high-velocity shot during a regional league soccer game. He immediately lost consciousness, collapsed, and was successfully resuscitated through early defibrillation of ventricular fibrillation. After an uneventful follow-up for approximately 6 years, recurrent episodes of ventricular tachycardia occurred, which could ultimately only be prevented by epicardial ablation. Very late recurrences of ventricular tachyarrhythmias may occur after ventricular fibrillation due to blunt chest trauma, even in the primary absence of evident structural myocardial damage.



#7 Association between Soccer Participation and Liking or Being Proficient in It: A Survey Study of 38,258 Children and Adolescents in China

Reference: Children (Basel). 2023 Mar 16;10(3):562. doi: 10.3390/children10030562.

Authors: Yibo Gao, Xiang Pan, Huan Wang, Dongming Wu, Pengyu Deng, Lupei Jiang, Aoyu Zhang, Jin He, Yanfeng Zhang

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Summary: Soccer participation among children and adolescents is low in China. To achieve a coordinated development of soccer in all regions and to promote the physical health of children and adolescents, this study aims to identify the influencing factors regarding the participation of children and adolescents in soccer programs through a cross-sectional analysis of the "soccer population" of children and adolescents. A total of 38,258 children and adolescents aged 7-18 years were included in this study. In addition, the analysis was conducted by dividing the regions where the children and adolescents live into three parts according to socioeconomic status, and by incorporating five dimensions, including environment, family, school, community, and individual levels to find the influencing factors of children and adolescents' participation in soccer. Chi-square test, Pearson's correlation, and one-way logistic regression analyses were used. The results showed that the area (r = 0.487) and the average annual precipitation (r = -0.367) were associated with the participation of children and adolescents in soccer programs. Moreover, the percentage of children and adolescents who participated in soccer programs (24.5%) was higher than those who liked soccer or were proficient in it (14.4%). Meanwhile, parental encouragement and support (OR = 0.627; 95% CI, 1.102-3.179), as well as the accessibility (OR = 0.558; 95% CI, 1.418-2.155), availability (OR = 1.419; 95% CI, 1.179-1.707), and safety of sports facilities (OR = 0.316; 95% CI, 0.614-0.865), influence children and adolescents' participation in soccer programs.



#8 Association between 2D:4D ratios and sprinting, change of direction ability, aerobic fitness, and cumulative workloads in elite youth soccer players

Reference: BMC Sports Sci Med Rehabil. 2023 Mar 28;15(1):45. doi: 10.1186/s13102-023-00654-y.

Authors: Hadi Nobari, Özgür Eken, Pablo Prieto-González, Rafael Oliveira, João Paulo Brito

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Summary: The aim of this study was two-fold: (i) to determine the correlation between 2D:4D, maximal oxygen uptake (VO2max), body fat percentage (BF%), maximum heart rate (HRmax), change of direction (COD), and accumulated acute and chronic workload variables; (ii) to verify if the length of the second digit divided by fourth digit (2D:4D) can explain fitness variables and accumulated training load. Twenty elite young football players (age: 13.26 ± 0.19 years; height: 165.8 ± 11.67 cm; body mass: 50.70 ± 7.56 kg; VO2max, 48.22 ± 2.29 1.min- 1) participated in the present study. Anthropometric and body composition variables (e.g., height, body mass, sitting height, age, BF%, body mass index, right and left finger 2D:4D ratios) were measured. The following fitness tests were also conducted: 30 - 15 Intermittent Fitness Test (VO2max and HRmax), COD (5-0-5 agility test), and speed (10-30msprint test. HRmax and the training load were also measured and monitored using the Rate of Perceived Exertion during the 26 weeks. There were associations between HRmax and VO2max, between 2D and 4D lengths and Left and Right hand ratios. Also, in AW with Right and Left 4D. The CW and de ACWR with the Right 4D. There were other associations between physical test variables and workload variables. Under-14 soccer players with low right and left-hand 2D:4D ratios did not perform better in the selected fitness tests to assess VO2max, COD, or sprint ability. However, it cannot be ruled out that the absence of statistically significant results may be related to the small sample size and the maturational heterogeneity of the participants.



#9 The role of working memory capacity in soccer tactical decision making at different levels of expertise

Reference: Cogn Res Princ Implic. 2023 Mar 29;8(1):20. doi: 10.1186/s41235-023-00473-2.

Authors: Dragan Glavaš, Mario Pandžić, Dražen Domijan

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Summary: Athletic skills acquired through deliberate practice are essential for expert sports performance. Some authors even suggest that practice circumvents the limits of working memory capacity (WMC) in skill acquisition. However, this circumvention hypothesis has been challenged recently by the evidence that WMC plays an important role in expert performance in complex domains such as arts and sports. Here, we have used two dynamic soccer tactical tasks to explore the effect of WMC on tactical performance at different levels of expertise. As expected, professional soccer players exhibited better tactical performance than amateur and recreational players. Furthermore, WMC predicted faster and more accurate tactical decisions in the task under auditory distraction and faster tactical decisions in the task without distraction. Importantly, lack of expertise × WMC interaction suggests that the WMC effect exists at all levels of expertise. Our results speak against the circumvention hypothesis and support a model of independent contributions of WMC and deliberate practice on expert performance in sports.



#10 Video analysis of Achilles tendon ruptures in professional male football (soccer) reveals underlying injury patterns and provides strategies for injury prevention

Reference: Knee Surg Sports Traumatol Arthrosc. 2023 Mar 28. doi: 10.1007/s00167-023-07384-1.

Authors: Tim Hoenig, Thomas Gronwald, Karsten Hollander, Christian Klein, Karl-Heinz Frosch, Peter Ueblacker, Tim Rolvien

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Summary: In professional football (soccer), Achilles tendon ruptures are severe injuries. Video analysis promotes a better understanding of the underlying situational and biomechanical patterns, and provides a roadmap for future research to improve the management and prevention of Achilles tendon ruptures. The purpose of this study was to identify injury patterns contributing to acute Achilles tendon ruptures in professional male football players. Professional male football players with an acute Achilles tendon rupture were identified using an online database. For every in-competition injury, the corresponding football match was detected. Video footage of the injury was accessed using or publicly available video databases. Situational patterns and injury biomechanics of the injury frame were independently analysed by two reviewers using a standardised checklist and a motion analysis software. Finally, consensus was reached to describe the main injury patterns of Achilles tendon ruptures in professional male football players. The search identified video footage of 80 Achilles tendon ruptures in 78 players. Most injuries (94%) occurred through indirect or non-contact mechanisms. The kinematic analysis revealed characteristic joint positions at the time of injury consisting of hip extension, knee extension, ankle dorsiflexion, foot abduction, and foot pronation in most cases. The underlying direction of movement was from flexion to extension (knee) and from plantarflexion to dorsiflexion (ankle). Player actions identified as main injury patterns were stepping back (26%), landing (20%), running/sprinting (18%), jumping (13%), and starting (10%). Most Achilles tendon ruptures in professional male football players are closed-chain indirect or non-contact injuries. Sudden loading to the plantarflexor musculotendinous unit remains to be the main component for most cases. By achieving a better understanding of underlying injury mechanisms, this study provides new strategies for the prevention of Achilles tendon ruptures.



#11 Effects of Concurrent High-Intensity and Strength Training on Muscle Power and Aerobic Performance in Young Soccer Players during the Pre-Season

Reference: Sports (Basel). 2023 Mar 6;11(3):59. doi: 10.3390/sports11030059.

Authors: Pierros Thomakos, Konstantinos Spyrou, Christos Katsikas, Nikolaos D Geladas, Gregory C Bogdanis

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Summary: The aim of the present study was to evaluate two different intervention programs applied during a 4-week pre-season period. Twenty-nine players participated in this study and were divided into two groups. One group (BallTrain, n = 12, age: 17.8 ± 0.4 years, body mass: 73.9 ± 7.6 kg, height: 178 ± 0.1 cm, body fat: 9.6 ± 5.3%) performed a higher percentage of aerobic training with ball and strength training using plyometrics and exercises with body weight. The other group (HIITTrain, n = 17, age: 17.8 ± 0.7 years, body mass: 73.3 ± 5.0 kg, height: 179 ± 0.1 cm, body fat: 8.0 ± 2.3%) trained with high-intensity interval training (HIIT) without the ball and performed resistance training with weights in the same session. Both groups trained for strength (two times/week) and performed aerobic-anaerobic fitness without the ball, passing games, and tactical and small-sided games. Lower limb power (CMJ) and aerobic fitness (Yo-Yo intermittent recovery test level 1-IR1) were evaluated before and after the four-week training program. Yo-Yo IR1 performance was improved in both groups, but the improvement was greater for the HIITTrain than BallTrain group (468 ± 180 vs. 183 ± 177 m, p = 0.07). CMJ showed a non-significant improvement in the BallTrain group (5.8 ± 8.8%, p = 0.16), but it decreased by 8.1 ± 9% (p = 0.001), in the HIITTrain group. In conclusion, we have shown that a short pre-season period of training results in improvements in aerobic fitness in both groups, with high-intensity interval training showing superior adaptations than training with the ball. However, CMJ performance was reduced in this group, possibly suggesting higher fatigue levels and overload, and/or showing the effects of concurrent HIITTrain and strength training in soccer.



#12 A data-driven framing of player and team performance in U.S. Women's soccer

Reference: Front Sports Act Living. 2023 Mar 8;5:1125528. doi: 10.3389/fspor.2023.1125528. eCollection 2023.

Authors: Sachin Narayanan, N David Pifer

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Summary: In establishing historical benchmarks for success on the pitch and striving to achieve parity off it, the United States Women's National Team (USWNT) and the National Women's Soccer League (NWSL) have long served as standard bearers for professional women's soccer around the globe. However, off-field dilemmas and incessant juxtapositions to men's soccer frequently overshadow the elements that make U.S. women's soccer unique; that is, in the quest to expose and rid the women's game of blatant misconduct, discriminatory practices, and negative stereotypes, relatively little attention has been devoted to performance features that separate the U.S. women's soccer product from its competition. Because many of the issues hindering the progress of women's soccer are rooted in media and managerial practices that marginalize or ignore its positive traits, a need exists for analyses that will properly identify its innate characteristics and competitive advantages so that media members, managers, and fans can accurately frame their perceptions of women competing in the sport. To this end, we collected reliable samples of public event data from 560 professional soccer matches and used ANOVAs and t-tests to identify the characteristics that distinguish U.S. women's soccer from other professional leagues and teams. In doing so, we showed that the USWNT tends to shoot from more opportune areas and press opponents at a higher rate, and that the NWSL has recently been matched in quality across certain performance metrics by England's FA Women's Super League.



#13 More than just a side effect: Dynamic knee valgus and deadbug bridging performance in youth soccer players and alpine skiers have similar absolute values and asymmetry magnitudes but differ in terms of the direction of laterality

Reference: Front Physiol. 2023 Mar 8;14:1129351. doi: 10.3389/fphys.2023.1129351. eCollection 2023.

Authors: Jonas Hanimann, Lynn Ellenberger, Thomas Bernhard, Martino V Franchi, Ralf Roth, Oliver Faude, Jörg Spörri

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Summary: From a preventative perspective, leg axis and core stabilization capacities are important for soccer players and alpine skiers; however, due to different sport-specific demands, the role of laterality clearly differs and may result in functional long-term adaptations. The aims of this study are 1) to determine whether there are differences in leg axis and core stability between youth soccer players and alpine skiers and 2) between dominant and non-dominant sides, and 3) to explore the outcomes of applying common sport-specific asymmetry thresholds to these two distinct cohorts. Twenty-one highly trained/national-level soccer players (16.1 years, 95% CI: 15.6, 16.5) and 61 alpine skiers (15.7 years, 95% CI: 15.6, 15.8) participated in this study. Using a marker-based 3D motion capture system, dynamic knee valgus was quantified as the medial knee displacement (MKD) during drop jump landings, and core stability was quantified as the vertical displacement during deadbug bridging exercise (DBB displacement ). For the analysis of sports and side differences, a repeated-measures multivariate analysis of variance was used. For the interpretation of laterality, coefficients of variation (CV) and common asymmetry thresholds were applied. There were no differences in MKD or DBB displacement between soccer players and skiers or between the dominant and non-dominant sides, but there was an interaction effect side*sports for both variables (MKD: p = 0.040, η2 p = 0.052; DBB displacement : p = 0.025, η2 p = 0.061). On average, MKD was larger on the non-dominant side and DBB displacement laterality on the dominant side in soccer players, whereas this pattern was reversed in alpine skiers. Despite similar absolute values and asymmetry magnitudes of dynamic knee valgus and deadbug bridging performance in youth soccer players and alpine skiers, the effect on the direction of laterality was opposite even though much less pronounced. This may imply that sport-specific demands and potential laterality advantages should be considered when dealing with asymmetries in athletes.



#14 Clinical Outcomes After ACL Reconstruction in Soccer (Football, Futbol) Players: A Systematic Review and Meta-Analysis

Reference: Sports Health. 2023 Mar 29;19417381231160167. doi: 10.1177/19417381231160167.

Authors: Ian S Hong, Lauren A Pierpoint, Justin E Hellwinkel, Alexander N Berk, Jonathan M Salandra, Joshua D Meade, Dana P Piasecki, James E Fleischli, Christopher S Ahmad, David P Trofa, Bryan M Saltzman

Summary: The risk factors for anterior cruciate ligament (ACL) tear for athletes participating in pivoting sports includes young age and female sex. A previous meta-analysis has reported a reinjury rate of 15% after ACL reconstruction (ACLR) for athletes across all sports. To the best of the authors' knowledge, this is the first systematic review and meta-analysis of available literature reporting outcomes after ACLR in soccer players. The aim was to review and aggregate soccer-specific outcomes data after ACLR found in current literature to help guide a more tailored discussion regarding expectations and prognosis for soccer players seeking operative management of ACL injuries. A comprehensive search of publications was performed using PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and SPORTDiscus databases. Inclusion criteria consisted of original studies, level of evidence 1 to 4, studies reporting clinical and patient-reported outcomes (PROs) after primary ACLR in soccer players at all follow-up length. The primary outcomes of interest were graft failure/reoperation rates, ACL injury in contralateral knee, return to soccer time, and PROs. Search of literature yielded 32 studies for inclusion that involved 3112 soccer players after ACLR. The overall graft failure/reoperation rate ranged between 3.0% and 24.8% (mean follow-up range, 2.3-10 years) and the combined ACL graft failure and contralateral ACL injury rate after initial ACLR was 1.0% to 16.7% (mean follow-up range, 3-10 years); a subgroup analysis for female and male players revealed a secondary ACL injury incidence rate of 27%, 95% CI (22%, 32%) and 10%, 95% CI (6%, 15%), respectively. Soccer players were able to return to play between 6.1 and 11.1 months and the majority of PROs showed favorable scores at medium-term follow-up.



#15 Association of Nonconcussive Repetitive Head Impacts and Intense Physical Activity With Levels of Phosphorylated Tau181 and Total Tau in Plasma of Young Elite Soccer Players

Reference: JAMA Netw Open. 2023 Mar 1;6(3):e236101. doi: 10.1001/jamanetworkopen.2023.6101.

Authors: Martin Cente, Janka Perackova, Pavol Peracek, Marek Majdan, Igor Toth, Martin Mikulic, Jozef Hanes, Sara Porubska, Marian Spajdel, Barbora Kazickova, Igor Jurisica, Peter Filipcik

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Summary: Head impacts resulting in traumatic brain injury (TBI) lead to the elevation of phosphorylated tau protein (p-tau181) in plasma. To our knowledge, this study is the first to investigate dynamics of p-tau181 levels and the ratio of p-tau181 to total tau in individuals after nonconcussive head impacts. The aim was o determine the association of repetitive low-intensity head impacts on p-tau181 and total tau protein levels in the plasma of young adult elite soccer players and assess the possible association of head impacts with focused attention and cognitive flexibility. In this cohort study, young elite soccer players performed intense physical activity with and without heading the ball. The study was conducted at a university facility in Slovakia from October 1, 2021, to May 31, 2022. Eligible participants were selected based on similarities in demographic variables, excluding those with a history of TBI. The primary study outcomes were the levels of total tau protein and p-tau181 in plasma samples and the cognitive status of the study participants. A total of 37 male athletes participated in the study (mean [SD] age: exercise group, 21.6 [1.6] years; heading group, 21.2 [1.5] years). We found significantly elevated levels of total tau and p-tau181 in the plasma of soccer players 1 hour after physical exercise (tau, 1.4-fold; 95% CI, 1.2-1.5; P < .001; p-tau181, 1.4-fold; 95% CI, 1.3-1.5, P < .001) and repetitive head impacts (tau, 1.3-fold; 95% CI, 1.2-1.4; P < .001; p-tau181, 1.5-fold; 95% CI, 1.4-1.7 P < .001). The ratio of p-tau181 to tau was significantly higher 1 hour after exercise and heading training, and remained elevated specifically in the heading group even after 24 hours (1.2-fold; 95% CI, 1.1-1.3; P = .002). Performance in cognitive tests revealed a significant decline in focused attention and cognitive flexibility after physical exercise and heading training; physical exercise of higher intensity without heading training was associated with a greater negative cognitive performance than heading only. In this cohort study of young elite soccer players, the elevation of p-tau181 and tau was observed after acute intense physical activity and nonconcussive repetitive head impacts. The increase of p-tau181 levels relative to tau after 24 hours indicated an acute enrichment of phosphorylated tau fraction in the periphery when compared with preimpact levels; an imbalance of tau proteins may have long-lasting consequences in the brain of head-impacted individuals.



#16 Developmental stage and lower quadriceps flexibilities and decreased gastrocnemius flexibilities are predictive risk factors for developing Osgood-Schlatter disease in adolescent male soccer players

Reference: Knee Surg Sports Traumatol Arthrosc. 2023 Mar 31. doi: 10.1007/s00167-023-07378-z.

Authors: Seira Takei, Suguru Torii, Shuji Taketomi, Satoshi Iizuka, Michio Tojima, Soichiro Iwanuma, Yukako Iida, Sakae Tanaka

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Summary: This study aimed to elucidate the influential predictive risk factors of Osgood-Schlatter disease (OSD) on the support (non-kicking) leg among adolescent soccer players considering peak height velocity (PHV) age and investigate the cut-off values of the predictive variables. A cohort of 302 Japanese adolescent male soccer players aged 12-13 years were followed over 6 months. All players underwent physical examination, tibial tubercle ultrasonography, anthropometric and whole-body composition measurements, and muscle flexibility test of the support leg at the baseline. The developmental stage was evaluated from the PHV age. The OSD of the support leg was diagnosed 6 months later; players were divided into the OSD and control (CON) groups. The predictive risk factors were analyzed by multivariate logistic regression analysis. There were 42 players who had developed OSD at baseline and they were excluded from the study. Among the 209 players, 43 and 166 belonged to the OSD and CON groups, respectively. The predictive risk factors of OSD development were PHV age ± 6 months at baseline (p = 0.046), apophyseal stage of tibial tuberosity maturity at baseline (p < 0.001), quadriceps flexibility ≥ 35° at baseline (p = 0.017), and decrease in gastrocnemius flexibility in 6 months (p = 0.009). PHV age ± 6 months at baseline, apophyseal stage of the tibial tuberosity at baseline, quadriceps flexibility ≥ 35° at baseline, and decrease in gastrocnemius flexibility in 6 months are predictive risk factors of OSD development in the support leg among adolescent male soccer players. It is crucial to know the PHV age of each player, and not only the flexibility of quadriceps muscle but also the gastrocnemius should be monitored to predict OSD.



#17 The effects of a 1-year recreational football protocol on bone health parameters in a group of healthy inactive 50-year-old men

Reference: J Clin Densitom. 2023 Mar 17;S1094-6950(23)00018-5. doi: 10.1016/j.jocd.2023.03.007.

Authors: Boutros Finianos, Antonio Pinti, Rawad ElHage

Summary: The main aim of the current study was to explore the effects of a 1-year recreational football protocol on bone health parameters (bone mineral content (BMC), bone mineral density (BMD), femoral neck geometry and composite indices of femoral neck strength) in a group of healthy inactive 50-year-old men. 51 middle-aged men voluntarily participated in this study, but only 41 of them completed it. Thus, the study population included 11 former football (FF) players and 30 inactive men. Inactive men were assigned to 3 different groups: controls (n=10), recreational football 30 (RF30; n=10) and recreational football 60 (RF60; n=10). The RF30 group performed two sessions of recreational football per week; the duration of each session was 30 minutes. The RF60 group performed two sessions of recreational football per week; the duration of each session was 60 minutes. The current study has demonstrated that whole body (WB) BMC, femoral neck BMD, cross-sectional moment of inertia, compression strength index, bending strength index and impact strength index increased in both experimental groups (RF30 and RF60) but not in the control group. The percentages of variations in bone health parameters were not significantly different between RF30 and RF60. In conclusion, this study suggests that recreational football is an effective method to improve bone health parameters in middle-aged men. In the studied population, most of the bone health benefits occurred after a low volume training protocol (2 * 30 minutes of recreational football per week).



#18 Cases of head injuries in football sport: A case study of Ghaziabad District, Uttar Pradesh

Reference: J Family Med Prim Care. 2022 Nov;11(11):6697-6703. doi: 10.4103/jfmpc.jfmpc_61_21. Epub 2022 Dec 16.

Authors: Kanishka Pandey

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Summary: In recent years public awareness of the potential long-term effects of concussions and mild traumatic brain injuries sustained in sport of football has increased. Players purposely use their head to direct the ball during play. There is a growing understanding of the link between blows to the head suffered in football and the potential for increased risk of injuries in later life.[1] This study aim is to reveal the similarities and differences the understanding of the link between blows to the head suffered in football and the potential for increased risk of injuries more specifically dementia in later life.[23] Heading an incorrect sized football can result in head injuries. As per FIFA guidelines a different sized football shall be used for different age groups. The schools in the Ghaziabad city were asked to fill in the questionnaires containing certain questions on Sports in general and football in particular. Descriptive and evaluative approach was used, which is generally used in comparative studies. The findings by various Universities established how heading can affect the brain, cognition, and speech of a person. It was found that a few developed nations like USA, England, Ireland have taken note of this issue and have issued guidelines based on the data and studies available. This study establishes that over-inflated footballs are being used in schools and also most of the schools have with them a single-sized football (which is against FIFA guidelines). Moreover, awareness of physical education instructors about different sizes of football and head injuries due to football is lacking. Also, clear guidelines on this issue are needed from the Ministry of Sports in India.



#19 Association between ACE and ACTN3 genes polymorphisms and athletic performance in elite and sub-elite Chinese youth male football players

Reference: PeerJ. 2023 Mar 24;11:e14893. doi: 10.7717/peerj.14893. eCollection 2023.

Authors: Shidong Yang, Wentao Lin, Mengmeng Jia, Haichun Chen

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Summary: Previous studies have shown controversial relationships between ACE I/D and ACTN3 R577x polymorphisms and athletic performance. Therefore, the aim of this study was to assess athletic performance indicators of Chinese youth male football players with different ACE and ACTN3 gene profiles. This study recruited 73 elite (26 13-year-olds, 28 14-year-olds, and 19 15-year-olds) and 69 sub-elite (37 13-year-olds, 19 14-year-olds, and 13 15-year-olds) and 107 controls (63 13-year-olds, and 44 14-year olds aged 13-15 years, all participants were of Chinese Han origin. We measured height, body mass, thigh circumference, speed, explosive power, repeat sprints ability, and aerobic endurance in elite and sub-elite players. We used single nucleotide polymorphism technology to detect controls elite and sub-elite players' ACE and ACTN3 genotypes, Chi-squared (χ 2) tests were employed to test for Hardy-Weinberg equilibrium. χ 2 tests were also used to observe the association between the genotype distribution and allele frequencies between controls and elite and sub-elite players. The differences in parameters between the groups were analyzed using one-way analysis of variance and a Bonferroni's post-hoc test, with statistical significance set at p ≤ 0.05. The genotype distribution of the ACE I/D and ACTN3 R577x polymorphisms in controls, elite and sub-elite football players were consistent with Hardy-Weinberg equilibrium, except for the ACE genotype distribution of sub-elite players.  The RR and DD genotypes were significantly different between elite and sub-elite players (p = 0.024 and p = 0.02, respectively).  Elite players were more likely to have the RR genotype and less likely to have the DD genotype compared with sub-elite players.  Both elite and sub-elite RR players' Yo-yo intermittent recovery level 1 (YYIR1) running distance was significantly longer than that of RX players (p = 0.05 and p = 0.025, respectively). However, there was no significantly different in YYIR1 running distance between elite and sub-elite RR players. Elite XX players' VO2 max was significantly higher than that of RX and sub-elite players. These results indicate that ACE I/D and ACTN3 R577x polymorphisms are not associated with muscle power in Chinese elite and sub-elite players. The XX genotype of ACTN3 is associated with the aerobic endurance of elite players.



#20 Examination of the ZXY Arena Tracking System for Association Football Pitches

Reference: Sensors (Basel). 2023 Mar 16;23(6):3179. doi: 10.3390/s23063179.

Authors: Jon Ingulf Medbø, Einar Ylvisåker

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Summary: Modern analyses of football games require precise recordings of positions and movements. The ZXY arena tracking system reports the position of players wearing a dedicated chip (transponder) at high time resolution. The main issue addressed here is the quality of the system's output data. Filtering the data to reduce noise may affect the outcome adversely. Therefore, we have examined the precision of the data given, possible influence by sources of noise, the effect of the filtering, and the accuracy of the built-in calculations. The system's reported positions of the transponders at rest and during different types of movements, including accelerations, were recorded and compared with the true positions, speeds, and accelerations. The reported position has a random error of ≈0.2 m, defining the system's upper spatial resolution. The error in signals interrupted by a human body was of that magnitude or less. There was no significant influence of nearby transponders. Filtering the data delayed the time resolution. Consequently, accelerations were dampened and delayed, causing an error of 1 m for sudden changes in position. Moreover, fluctuations of the foot speed of a running person were not accurately reproduced, but rather, averaged over time periods >1 s. Results calculated from measured values appeared accurate and were readily reproduced in a spreadsheet output. In conclusion, the ZXY system reports the position with little random error. Its main limitation is caused by averaging of the signals.

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