Purpose Muscle injuries are common in professional football, even though prevention protocols are being implemented. Genetics constitutes a novel ield for studying intrinsic injury risks and performance. Since previous studies involving single nucleotide polymorphisms (SNPs) have shown that SNPs inluence muscle injury rate, injury severity and recovery time, the aim was to study the association the SNP of ACTN3 has with those parameters in professional football players. Methods The medical staf team recorded non-contact musculoskeletal soft-tissue injuries in 43 professional football players in 7 diferent seasons (2007-2012 and 2015-2016). Injury rate, injury severity and injury recovery times were established. Players were genotyped by extracting DNA from a blood sample and using a polymerase chain reaction. Results Injury rate was associated with the SNP of ACTN3 (p = 0.003). The 577R allele was more frequent in subjects than in a normal population by showing presence in 93% of the subjects and suggesting that it could inluence football performance. No statistically signiicant diferences in injury severity and recovery time were associated with the SNP of ACTN3. Conclusions Genetics is gaining in importance when assessing injury risk and performance in professional football. ACTN3 can be regarded as a biomarker of injury susceptibility in this discipline. Identifying those players with the highest injury susceptibility through genetics could lead football teams to individualise workloads and prevention protocols. Level of evidence III. Keywords Single nucleotide polymorphism • Football • Muscle injuries • GeneticsEnric Clos and Ricard Pruna contributed equally to the study.

Introduction: Football is characterised by intermittent high-intensity efforts varying according to the field position of a player. We aimed to ascertain whether polymorphisms in the ACTN3 gene are associated with different playing positions in elite professional football players. Subjects and Methods: Genotyping of the ACTN3 gene was conducted in 43 elite professional football players of a single team. Playing position was recorded based on the player’s most frequent position. Results: The genotype distribution was not significant between positions (p = 0.057), while the allele distribution differed significantly (p = 0.035). Goalkeepers (p = 0.04, p = 0.03), central defenders (p = 0.03, p = 0.01), and central midfielders (p = 0.01, p = 0.00) had a significantly different allele distribution compared with wide midfielders and forward players. Conclusions: Genetic biomarkers may be important when analysing performance capability in elite professional football. Identifying the genetic characteristics of a player to adapt his playing position may lead to orientation of positions based on physical capabilities and tissue quality in young football players, and also to performance enhancement in those who are already playing in professional teams.

SummaryThe identification of risk factors and the assessment of athlete's predisposition to suffer an injury and the way in which it will occur is hard to predict due to the multifactorial origin of the lesions. In recent years, the importance of the genetic component of each individual as a possible cause of injury predisposition is being evaluated.The objective of this work was to write a review of the genetic studies carried out to date on connective tissue injuries and propose future research lines that would allow the development of more personalized training programs and specify preventive therapies in order to reduce the injury risk.The multifactorial origin of injuries complicates the identification of risk factors (extrinsic and intrinsic factors). Together, these factors and their interaction predisposes an athlete to injuries. In recent years, the genetic component of each individual as a possible cause of injury predisposition has become of importance.The aim of this article was to propose a review of published genetic studies related to connective tissue repair or regeneration and to pave the way for future Sports Medicine Research. This information could be very useful in order to individualize the preventive strategies to avoid injuries and to optimize the therapeutic and rehabilitation process after injuries.Applied biology is already contributing new knowledge by providing new biomarkers that will give information and increase understanding regarding the susceptibility of individuals to suffer certain types of injury. Genetic analysis can offer us reliable and objective predictive parameter that combined with the current methods of analysis will help improve the performance and management of athletes.

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