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It is currently unknown if injury risk is associated with genetic variation in academy soccer players (ASP). We investigated whether nine candidate single nucleotide polymorphisms were associated (individually and in combination) with injury in ASP at different stages of maturation. Saliva samples and one season's injury records were collected from 402 Caucasian male ASP from England, Spain, Uruguay, and Brazil, whose maturity status was defined as pre‐ or post‐peak height velocity (PHV). Pre‐PHV COL5A1 rs12722 CC homozygotes had relatively higher prevalence of any musculoskeletal soft tissue (22.4% vs. 3.0%, p = 0.018) and ligament (18.8% vs. 11.8%, p = 0.029) injury than T‐allele carriers, while VEGFA rs2010963 CC homozygotes had greater risk of ligament/tendon injury than G‐allele carriers. Post‐PHV IL6 rs1800795 CC homozygotes had a relatively higher prevalence of any (67.6% vs. 40.6%, p = 0.003) and muscle (38.2% vs. 19.2%, p = 0.013) injuries than G‐allele carriers. Relatively more post‐PHV EMILIN1 rs2289360 CC homozygotes suffered any injury than CT and TT genotypes (56.4% vs. 40.3% and 32.8%, p = 0.007), while the "protective" EMILIN1 TT genotype was more frequent in post‐ than pre‐PHV ASP (22.3 vs. 10.0%, p = 0.008). Regardless of maturity status, T‐alleles of ACTN3 rs1815739 and EMILIN1 rs2289360 were associated with greater absence following ankle injury, while the MMP3 rs679620 T‐allele and MYLK rs28497577 GT genotype were associated with greater absence following knee injury. The combination of injury‐associated genotypes was greater in injured vs. non‐injured ASP. This study is the first to demonstrate that a genetic association exists with injury prevalence in ASP, which differs according to maturity status. [ABSTRACT FROM AUTHOR]

The current study examined how sleep may be influenced by the scheduling of training and match load within 10 youth-soccer players. Sleep was measured over a 14-day in-season period using a commercially available wireless sleep monitor. Each collected sleep variable; lights out, sleep latency, total sleep time wake after sleep onset and final awakening, was compared for the specific day within the training schedule (e.g. match day [MD], day after match [MD + 1]) and to training/match load (high-speed distance (>5.5 m/s) [HSD] and rating of perceived exertion. The data were analysed using mixed models and effect sizes, to describe the magnitude of effects that training schedule and training load may have on sleep. A reduction of sleep duration was observed on the day after the match (MD + 1) in relation to the training days preceding the match (MD-2: −65 min, ES: 0.89 ± 0.79; MD-1 −61 min, ES: 0.82 ± 0.64) and reduction on match day (+45 min; ES: 1.91 ± 1.69). This may suggest youth-soccer players actively change their sleep scheduling behaviours in relation to the imposed soccer schedule. Increased high-speed running (for every 100 m) showed a small increase to total sleep time (+9 min; ES: 0.48 ± 0.31). This may suggest that increases in training load may be associated with small increases in sleep quantity. Such observations may highlight that the type of day and the associated load within the training microcycle may have important consequences for sleep within youth-soccer players. [ABSTRACT FROM AUTHOR]