Experimental Paradigm for Studying Abnormal Hip Torque Coupling During Gait Initiation After Stroke

Post-stroke lower limb impairments cause significant challenges in balance during gait initiation. While studies have mainly focused on behavioral impacts of these impairments, the understanding of neutral constraints persist a significant gap. This study is aimed to investigate the abnormal hip extension- adduction coupling previously found in individuals with stroke. We hypothesize that when stepping with the non paretic limb, the reduced ability in the paretic standing limb to abduct while extending will impact frontal plane 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. Towards this end, here we present the initial development and validation of the proposed paradigm in one healthy participant, under two (normal and long) steps x (with and without) resistance conditions. Our experimental setup successfully increased hip extension torque demand, which is expected to induce abnormal hip extension- adduction coupling in individuals with stroke. The findings from this experiment will show the effects of neural constraints on the lower limb after stroke during tasks such as gait initiation which may be effective for future therapeutic interventions.