Kinematic Correlates of Kinetic Outcomes Associated With Running-Related Injury.

ABSTRACT

High magnitudes and rates of loading have been implicated in the etiology of running-related injuries. Knowledge of kinematic variables that are predictive of kinetic outcomes could inform clinic-based gait retraining programs. Healthy novice female runners ran on a treadmill while 3-dimensional biomechanical data were collected. Kinetic outcomes consisted of vertical impact transient, average vertical loading rate, instantaneous vertical loading rate, and peak braking force. Kinematic outcomes included step length), hip flexion angle at initial contact, horizontal distance from heel to center of mass at initial contact, shank angle at initial contact, and foot strike angle. Stepwise multiple linear regression was used to evaluate the amount of variance in kinetic outcomes explained by kinematic outcomes. A moderate amount of variance in kinetic outcomes (vertical impact transient = 46%, average vertical loading rate = 37%, instantaneous vertical loading rate = 49%, peak braking force = 54%) was explained by several discrete kinematic variables-predominantly speed, horizontal distance from heel to center of mass, foot strike angle, and step length. Hip flexion angle and shank angle did not contribute to any models. Decreasing step length and transitioning from a rearfoot strike may reduce kinetic risk factors for running-related injuries. In contrast, clinical strategies such as modifying shank angle and hip flexion angle would not appear to contribute significantly to the variance of kinetic outcomes after accounting for other variables.