THE INFLUENCE OF TIBIALIS ANTERIOR MUSCLE-ACTIVITY ON REARFOOT MOTION DURING WALKING

The purpose of this study was to determine whether tibialis anterior muscle activity influences the rate of rear-foot motion during walking. Two-dimensional rearfoot motion was recorded from 23 feet. The feet were assigned to one of two experimental groups. Muscle activity was recorded from the tibialis anterior muscle using surface electrodes. The early pronators (N = 12) reached maximal pronation within the first 20% of the stance phase. The late pronators (N = 11) reached maximal pronation only after 40% of the stance phase. The results of a t-test showed that there was a significant difference (P < .05) in the time to minimal tibialis anterior muscle activity between the two groups. These results indicate that tibialis anterior muscle activity can influence rearfoot motion during the stance phase of walking. A clinician should consider the muscular system when evaluating and designing a treatment program for patients with foot-related problems. The results of this study also indicate that static nonweightbearing evaluations alone may not provide an accurate picture of the foot during walking.