Inward platform translations during treadmill walking enhance lateral weight shift and paretic leg engagement in chronic stroke.

Post-stroke gait is often characterized by compromised lateral weight transfer toward the paretic limb, which diminishes loading and engagement of the paretic limb. Strategies that promote lateral weight shift toward the paretic side may facilitate improved paretic-leg loading and neuromuscular activation. In this context, perturbation-based paradigms that disrupt stability may offer a unique advantage for promoting recovery. The purpose of this study was to determine whether treadmill-based lateral perturbations, delivered via inward platform translations, facilitate weight transfer to the paretic side and increase paretic-leg engagement in individuals with chronic stroke. Thirteen individuals post-stroke completed two randomized testing conditions: (1) treadmill walking with lateral perturbations applied during the paretic stance phase, and (2) a control condition without perturbations. Both conditions included baseline, adaptation, post-adaptation, and re-adaptation periods. Overground walking was assessed before, immediately after, and 10 min after treadmill walking. Lateral perturbations elicited a significantly greater increase in maximum center of pressure (COP) displacement from baseline during post-adaptation, compared with the control condition (p ≤ 0.01). Similarly, activation of the paretic hip abductors and adductors was significantly augmented in the late post-adaptation phase of the perturbation condition (p < 0.03). Furthermore, overground pelvis displacement toward the paretic side showed greater improvement 10 min after the lateral perturbation session, compared with the control session (p = 0.044). In conclusion, lateral perturbation during treadmill walking effectively enhances weight shifting toward the paretic leg and promotes paretic limb engagement, representing a promising strategy to target specific mechanical deficits in post-stroke gait.