Association between training volume and lower extremity overuse injuries in young female athletes: implications for early sports specialization.

Background: Recent studies indicated greater risk of overuse injuries among young female athletes than their male counterparts. However, few studies have focused on female athletes and the effect of single-sport participation on lower extremity overuse injuries. Objective: The objective of this study is to identify an independent risk variable for lower extremity overuse injuries based on status of sport participations (single- and multisports) in young female athletes. Methods: In this cross-sectional study, 12-18-year-old female athletes were asked to complete electronic questionnaires describing their current sport participation and previous injury history. Range of motion (ROM), muscular strength, and performance parameters were measured at the time of completion of electronic questionnaires. Potential risk variables were compared between single- and multisport athletes and entered into a logistic regression model. Adjusted odds ratio (aOR), 95% confidence intervals (95% CIs), and p values were recorded to find an association with increased likelihood of lower extremity overuse injuries. Results: The study cohort comprised 236 female young athletes (single-sport athletes: N = 60, multisport athletes: N = 176). A few variables including age, BMI, weekly hours of training for a sport, knee ROM, ankle ROM, and knee extensor strength were identified as potential risk variables. A logistic regression analysis showed an independent association between increased weekly hours of training for a sport and greater likelihood of histories of lower extremity overuse injuries (aOR = 1.091, 95% CIs: 1.007-1.183, p = .034). Conclusion: Although status of single- or multisports participation was not a significant risk variable, increased training volume was found to be an independent contributing factor for greater likelihood of lower extremity overuse injury histories in 12-18 years female athletes. The current study identified that single-sport athletes trained nearly twice as many hours per week when compared to multisport athletes, which may explain an underlying mechanism of sports specialization.