Intentionally Lengthening Nonparetic Step Length Inhibits the Paretic-Side Swing-Phase Ankle Motion More than Knee Motion

Abstract

Gait training to intentionally lengthen the nonparetic step length can increase the propulsive force of the paretic leg but may also induce overactivity of the knee extensor muscles that might limit knee flexion during the swing phase. Herein, we investigated the effects of lengthening the nonparetic step length during gait on the joint motion and muscle activity of the paretic lower limb. Fifteen chronic stroke patients (stroke group) and 15 healthy participants (control group) were evaluated for lower limb joint movements, electromyography, and spatiotemporal gait parameters during walking. Walking conditions were Normal (comfortable walking) and NP-Long/Contralateral-Long (walking with a lengthened step length of the nonmeasured limb). The trailing limb angle, a surrogate for propulsive forces, was increased in both groups by changing the step length, with no significant change in the peak knee flexion angle during the swing phase. However, the stroke group did not increase ankle plantar flexor activity in the stance phase or ankle dorsiflexion angle in the swing phase. Intentionally lengthening the nonparetic step length did not limit knee flexion. However, the effect of increased propulsive force during the stance phase was insufficient, with the possibility of decreased foot clearance.

Keywords

• stroke
• gait
• kinematics
• electromyography
• trailing limb angle