People with Chronic Stroke Adopt Gait Patterns That Enhance Control of Center-of-Mass Dynamics in Response to Movement Amplification

There is a need to develop effective physical therapy interventions to enhance walking balance in ambulatory people with chronic stroke (PwCS). Interventions that amplify selfgenerated movements may accelerate motor learning by enhancing sensorimotor feedback. Here, we applied this concept to walking balance. Specifically, during treadmill walking we used a cable-driven robot to apply lateral forces to the pelvis of 19 PwCS that were proportional in magnitude to real-time lateral center of mass (COM) velocity. The resulting movement amplification (MA) field increased the challenge to control lateral motion of the COM. We found that following $10-{\min}$ of walking in the MA field, PwCS responded by adopting gait patterns that significantly increased control of COM dynamics (reduced lateral excursion and peak lateral velocity) and resulted in moderate but nonsignificant improvements in symmetry when compared to walking in a Null (no applied forces) field. These findings motivate further investigation to explore if extended walking practice performed in an MA field can improve walking balance in PwCS.