Effect of static foot alignment on plantar-pressure measures during running.

CONTEXT Altered foot dynamics due to malalignment of the foot may change plantar-pressure properties, resulting in various kinds of overuse injuries. OBJECTIVE To assess the effect of foot characteristics on plantar-pressure-related measures such as maximum pressure, maximum pressure-time, and pressure-time integral underneath the medial aspect of the foot during running. DESIGN Cross-sectional. SETTING Laboratory. PARTICIPANTS 8 men and 17 women. MAIN OUTCOME MEASURES Static non-weight-bearing rear-foot and forefoot alignment and navicular drop were measured. Plantar-pressure data were collected while subjects jogged at 2.6 m/s on a treadmill. Maximum pressure, time to maximum pressure, and pressure-time integral of the medial side of the foot were extracted for data analysis. Multiple-regression analysis was used to examine the effect of arch height and rear-foot and forefoot alignment on maximum pressure and pressure-time integral in the medial side of the foot. RESULTS In the medial rear-foot and midfoot regions, only rear-foot alignment had a significant effect on the variance of maximum pressure and pressure-time integral. There were no significant difference effects in the medial forefoot region. CONCLUSION Rear-foot alignment was found to be a significant predictor of maximum plantar pressure and pressure-time integral in the medial rear-foot and midfoot regions. This indicates that control of rear-foot alignment may help decrease plantar pressure on the medial region of the foot, which may potentially prevent injuries associated with excessive rear-foot eversion.