Determining the Effects of Increased Demands for Voluntary Adjustments on the Neuromuscular Control of Walking Post-stroke

This proposal aims to determine the effects of explicitly driven or implicitly driven walking modifications on muscle activation patterns and co-contraction post-stroke. This work is significant, as studies have shown that muscle activation patterns after neurologic injury cannot generate walking kinematics comparable to those seen in neurotypical individuals; this finding implies that to attain true walking recovery after neurologic injury, interventions should aim to restore the muscle activations underlying walking behaviors. Here, the researchers first explore muscle activations during walking using biofeedback to guide explicit modification of walking patterns, which is a common approach used in clinical and research interventions for walking retraining. The hypothesis is that explicit walking modifications might be detrimental at a muscle activation level as they engage cortical pathways for voluntary control that have been interrupted by the stroke lesion, resulting in increased muscle co-contraction. Co-contraction hinders true recovery as it impairs the ability to selectively control different segments during walking, resulting in overreliance on compensatory patterns. Researchers will also explore muscle activation patterns during implicit walking modifications. Researchers will use external modifications in the walking environment, mainly split-belt adaptation followed by tied belt walking, to assess if implicit modifications of walking that rely less on cortical neural control are associated with levels of cocontraction comparable to neurotypical controls-an indication that implicitly-mediated modifications could be a more effective approach to restore muscle activation patterns during walking post-stroke. In this study, researchers will assess co-contraction during walking in people post-stroke as the patient reduces asymmetry in step lengths guided by explicit biofeedback (Aim 1) or implicitly following split-belt adaptation and washout (Aim 2). Results from this study will identify the tasks and conditions that can reduce cocontraction to promote restoration of neuromuscular control post-stroke. This proposal will aid develop objective markers of treatment response and functional progress that predict rehabilitation treatment response and enable the tailoring of interventions to the needs, abilities, and resources of the person with disability.