Risk factors for injury in indoor compared with outdoor adolescent soccer

Background: There are limited data on the epidemiology of indoor soccer injuries. Purpose: Injury rates and risk factors for injury in adolescent indoor and outdoor soccer in the same cohort of players will be identified and compared. Study Design: Cohort study (prevalence); Level of evidence, 2. Methods: The study population was a random sample of 21 adolescent (ages 13-17 years) outdoor soccer teams (N = 317). The subcohort included players continuing to play in the indoor soccer season (n = 142). The injury definition included any injury occurring in soccer that resulted in medical attention, the inability to complete a session, and/or missing a subsequent session. Results: The overall injury rate found in indoor soccer over 20 weeks was 4.45 injuries per 1000 player hours (95% confidence interval, 3.1-6.19). The overall injury rate found in the 13-week outdoor soccer season among a similar cohort was 5.59 injuries per 1000 player hours (95% confidence interval, 4.42-6.97). The relative risk of injury suggests that there was no significant difference between injury rates by age group or gender in indoor soccer compared with outdoor soccer. The risk of injury in the most elite division of play was greater in outdoor compared with indoor soccer (relative risk, 3.22; 95% confidence interval, 1.8-6.12). The most commonly injured body part in both indoor and outdoor soccer was the ankle, followed by the groin in indoor and the knee in outdoor soccer. Conclusion: There were no significant differences in overall injury rates found by gender or age group for indoor compared with outdoor soccer. Future research should focus on injury prevention strategies to reduce lower extremity injury in indoor and outdoor adolescent soccer.