Muscle Injuries in Elite Youth Football Academy: A Six-Year Longitudinal Study on the U15 Football Team

To develop specific preventive strategies, it is necessary to investigate in detail the occurrence of injuries in young football players. This study aimed to provide details about the type, location, severity, and contact nature of muscle injuries in elite U15 Croatian football players. A total number of 130 muscle injuries occurred during the six competitive seasons, of which 88 were DOMS injuries and 42 were rupture injuries. Specifically, 87% of all muscle injuries belonged to the four major groups, with only 15 injuries to the other muscle groups: hamstrings (43), quadriceps (41), adductors (25), calves (6). The muscle injury incidence was stable during the observed period as the injury incidence rate ratio (IRR) was 1.01 (95%CI: 0.99–1.03), with 3.13 (95%CI: 3.09–3.17) muscle injuries per 1000 h of exposure in the first season and 3.06 (95%CI: 3.02–3.1) in the sixth season. A significantly higher risk for muscle injuries was discovered in the competition as the incidence for the whole observed period was 7.38 (95%CI: 7.29–7.47) compared to 2.25 (95%CI: 2.24–2.26) in the training period. Despite the relatively stable number of sustained muscle injuries, the relative proportion of muscular injuries increased over the years due to a severe decrease in the total number of injuries. Regarding the proportion of players who had sustained a muscle injury, our results suggest that approximately two out of five players can expect a muscular injury over the one-season period. Relatively high injury expectancy rates, as well as reinjury rates, require specific preventive interventions that will reduce the number and severity of new and recurred injuries. Future studies should include a wide set of predictor variables in order to establish the most important injury risk factors.