Nonparetic tibialis anterior muscle activity during gait: Association with step length asymmetry in chronic stroke patients.

Abstract

Gait disturbances following stroke often involve abnormal muscle activity of the nonparetic lower limb as a compensatory movement. Among the multiple muscles, the tibialis anterior muscle is particularly involved in balance, and tibialis anterior muscle activity may influence gait parameters such as gait speed and asymmetry. However, the role of nonparetic tibialis anterior muscle activity in hemiplegic gait is not yet fully understood. This study included 19 chronic stroke patients and 19 healthy controls. Surface electromyography was employed to measure nonparetic tibialis anterior muscle activity during gait. The gait speed, swing time asymmetry index, and step length asymmetry index were analyzed. Furthermore, statistical analyses were conducted to compare muscle activity between the groups and assess correlation analysis with gait parameters. Stroke patients exhibited significantly higher nonparetic tibialis anterior muscle activity during the early single support phases than the healthy controls (P < 0.001, d = 1.30). Nonparetic tibialis anterior muscle activity during the early single support phase was negatively correlated with the step length asymmetry index (P = 0.02, r = -0.52). The increase in nonparetic tibialis anterior muscle activity in the early single support phase is characteristic of stroke patients and may be a compensatory movement for step length asymmetry. Excessive nonparetic tibialis anterior activity may prevent recovery of paretic side swing function. While rehabilitation typically focuses on the paretic side, this study suggests that nonparetic tibialis anterior activity plays a pivotal role in achieving functional gait.