Comparing Aftereffects after Split-Belt Treadmill Walking and Unilateral Stepping

Abstract

Asymmetric step length is a problem common to many orthopedic and neurologic populations. Herein, we compare step length aftereffects during overground gait after two rehabilitation intervention strategies to combat step length asymmetry: split-belt treadmill (SBT) walking and unilateral stepping. Eighteen healthy young adults (22 ± 3 yr) first performed 10 overground gait trials. Participants then walked for 10 min under three different treadmill conditions in a randomized order: SBT walking, slow unilateral stepping, and fast unilateral stepping. Immediately after each treadmill condition, participants performed ten overground gait trials. Mean step length asymmetry was calculated across the first five strides of the overground gait trials to assess the storage of aftereffects after each treadmill condition. We also explored the lower extremity kinematics during each treadmill condition to investigate movement patterns that lead to greatest aftereffects. Significantly higher step length asymmetry was observed in overground gait trials after SBT walking compared to those after slow and fast unilateral stepping, indicating greater aftereffect/carryover of the SBT walking pattern to overground gait. During fast unilateral stepping, increased flexion in the hip, knee, and ankle of the stationary limb was significantly associated with increased step length aftereffects. The aftereffects observed after acute SBT walking were significantly greater than those after unilateral stepping. Both exercises induce aftereffects of similar kinematic patterns, although likely through different mechanisms. In sum, SBT walking induces the greatest aftereffects, although unilateral stepping also induces a change in gait behavior. During unilateral stepping, the largest aftereffects occur when the walker does not simply fully extend the stationary limb and allow the treadmill to passively move the stepping limb during stance.