Estimation of vertical ground reaction force parameters during athletic tasks using 2D video.

Abstract

Given that elevated vertical ground reaction forces (vGRF) have been reported to contribute to various lower-extremity injuries, there is a need for a practical method to characterize movement behavior that is representative of elevated impact forces. Can images obtained from 2D video be used to predict vGRF parameters during athletic tasks? Specifically, we sought to determine whether the 2D thigh angle obtained at peak knee flexion could be used to predict the peak vGRF and vGRF impulse during single limb and double limb landings and movements that involve a change of direction. 2D sagittal plane video and vGRFs were obtained simultaneously from 39 participants (15 males and 24 females) during 5 athletic tasks (drop jump, lateral shuffle, deceleration, triple hop, side-step-cut). Linear regression analysis was performed to determine if the 2D thigh angle at peak knee flexion predicted the first peak of the vGRF and vGRF impulse during the deceleration phase of each task. The 2D thigh angle predicted the peak vGRF for all tasks except cutting (R2 = 0.17 to 0.47, all p < 0.01). However, the 2D thigh angle predicted the vGRF impulse for all 5 tasks (R2 = 0.13 to 0.39, all p < 0.025). An increased 2D thigh angle (which is representative of increased hip and knee flexion) was able to predict lower peak vGRFs and vGRF impulse during athletic tasks. The 2D thigh angle is a potential clinical method to characterize movement behavior that may expose individuals to high impact forces.