Enhancing Hip Extension in Gait Initiation to Study Abnormal Hip Extension-Adduction Coupling in Stroke

Lower limb motor deficits after stroke pose significant challenges to balance during gait initiation, particularly in the frontal plane. While studies have largely focused on behavioral aspects of these impairments, there remains a notable gap in understanding the underlying neural mechanisms. This study aims to elucidate the impact of stroke-induced neural constraints in controlling various degrees of freedom in the paretic leg following a stroke, which likely stems from an increased reliance on brainstem motor pathways in place of the injured corticospinal pathways. Specifically, we focus on the abnormal coupling between hip extension and adduction torques previously found in individuals with stroke during isometric torque generation tasks. We hypothesize that when stepping with the nonparetic limb, the reduced ability in the paretic standing limb to abduct while extending will impact frontal plane behavior/balance. To test our hypothesis, we propose to induce the abnormal hip extension-adduction coupling by increasing hip extension torque demand in the stance limb during gait initiation with a longer step and/or by applying resistance through a passive exosuit. In this study with 5 stroke, 2 control participant, our goal was to validate the experimental design in demanding the level of hip extension torque demand would impact hip abduction degrees of freedom.