LAUSR

Objectives: Sports specialization has become increasingly common among youth. Our goal was to examine the independent prospective associations of sports specialization and volume of activity with injury risk in youth. Methods: A prospective analysis in 2018 using data collected from 10,138 youth in the Growing Up Today Study, a prospective cohort study of youth throughout the United States, and their mothers. Activity was assessed via questionnaires in 1997, 1998, 1999 and 2001. Sports specialization was defined as engaging in one sport in the fall, winter, and spring. Injury history was provided by participants’ mothers via questionnaire in 2004. The outcome was incident stress fracture, tendinitis, chondromalacia patella or anterior cruciate ligament tear. Results: Females who engaged in sports specialization were at increased risk of injury (females: hazard ratio (HR)=1.31, 95% confidence interval (CI) 1.07 -1.61), but risk varied by sport. In both genders sports specialization was associated with greater volume of physical activity (p<0.0001). Total hours/week of vigorous activity was predictive of developing injury (males: HR=1.04, 95% CI 1.02 -1.06; females: HR=1.06, 95% CI 1.05 -1.08). Among the females even those engaging in 3-3.9 hours per week less than their age were at a significantly increased risk of injury (HR=1.93, 95% CI 1.34-2.77). In males there was not a clear pattern of risk. Conclusion: Sports specialization is associated with higher volume of vigorous sports activity and increased risk of injury. Parents, coaches, and medical providers need to be made aware of the volume threshold above which physical activity is excessive.