Motor Performance as Risk Factor for Lower Extremity Injuries in Children.

Purpose: Physical activity-related injuries in children constitute a costly public health matter. The influence of motor performance on injury risk is unclear. The purpose of this study was to examine if motor performance was a risk factor of traumatic and overuse lower extremity injuries in a normal population of children.

Methods: This study included 1244 participants from 8 to 14 yr old at baseline, all participating in the "Childhood Health, Activity and Motor Performance School Study Denmark." The follow-up period was up to 15 months. The motor performance tests were static balance, single leg hop for distance, core stability tests, vertical jump, shuttle run, and cardiorespiratory fitness test. Lower extremity injuries were registered by clinicians using weekly questionnaires and classified according to the International Classification of Diseases, 10th Revision, system.

Results: Poor balance increased the risk for traumatic injury in the foot region (incidence rate ratio [IRR] = 1.09-1.15), and good performance in single leg hop for distance protected against traumatic knee injuries (IRR = 0.66-0.68). Good performance in core stability tests and vertical jump increased the risk for traumatic injuries in the foot region (IRR = 1.12-1.16). Poor balance increased the risk for overuse injuries in the foot region (IRR = 1.65), as did good performance in core stability tests and shuttle run, especially for knee injuries (IRR = 1.07-1.18).

Conclusions: Poor balance (sway) performance was a consistent predictor of traumatic injuries, in particular, for traumatic ankle injuries. Good motor performance (core stability, vertical jump, and shuttle run) was positively associated with traumatic and overuse injuries and negatively (single leg hop) associated with traumatic injuries, indicating different influences on injury risk. Previous injury was a confounder affecting the effect size and the significance. More studies are needed to consolidate the findings, to clarify the influence of different performance tests on different types of injuries, and to examine the influence of behavior in relation to injury risk.