Examining Measures of Weight as Risk Factors for Sport-Related Injury in Adolescents.

Objectives. To examine body mass index (BMI) and waist circumference (WC) as risk factors for sport injury in adolescents. Design. A secondary analysis of prospectively collected data from a pilot cluster randomized controlled trial. Methods. Adolescents (n = 1,040) at the ages of 11-15 years from two Calgary junior high schools were included. BMI (kg/m(2)) and WC (cm) were measured from direct measures at baseline assessment. Categories (overweight/obese) were created using validated international (BMI) and national (WC) cut-off points. A Poisson regression analysis controlling for relevant covariates (sex, previous injury, sport participation, intervention group, and aerobic fitness level) estimated the risk of sport injury [incidence rate ratios (IRR) with 95% confidence intervals (CI)]. Results. There was an increased risk of time loss injury (IRR = 2.82, 95% CI: 1.01-8.04) and knee injury (IRR = 2.07, 95% CI: 1.00-6.94) in adolescents that were overweight/obese; however, increases in injury risk for all injury and lower extremity injury were not statistically significant. Estimates suggested a greater risk of time loss injury [IRR = 1.63 (95% CI: 0.93-2.47)] in adolescents with high measures of WC. Conclusions. There is an increased risk of time loss injury and knee injury in overweight/obese adolescents. Sport injury prevention training programs should include strategies that target all known risk factors for injury.