Evaluation of a Method to Estimate Foot Eversion Moments During the Support Phase of Running

Excessive external eversion moments acting on the ankle derived from the ground reaction force (GRF) during the support phase of running are considered a risk factor for overuse lower-limb injuries. The external eversion moment is considered to be dominated by the moment derived from the vertical GRF. However, no studies have directly evaluated the accuracy with which external eversion moment can be estimated with this information. Thus, the objective of this study was to evaluate the extent to which external eversion moment can be estimated from external eversion moment derived from vertical GRF.

From three-dimensional foot coordinates and GRF data of 28 healthy participants, we computed external eversion moment (EMrun), center of the ankle coordinates (ANKrun), center of pressure coordinates (COPrun), and vertical GRF (VGRFrun) during the support phase of running. Moreover, we computed center of the ankle joint coordinates (ANKstand) and vertical GRF (VGRFstand) in the resting standing position.

A highly significant correlation was observed between EMrun and external eversion moment derived from vertical GRF ([COPrun - ANKrun] × VGRFrun), with a contribution of 84.7%. Moreover, a highly significant correlation was observed between EMrun and (COPrun - ANKstand) × VGRFstand, with a contribution of 81.5%.

These results indicate that external eversion moment can be estimated from the external eversion moment derived from vertical GRF with high accuracy. Moreover, it was found that the accuracy did not decrease even if the data of center of ankle and vertical GRF were replaced with the data during standing.