Movement Amplification Gait Training to Enhance Walking Balance Post-Stroke

Background: There is a pressing need to develop effective methods to enhance walking balance in people with chronic stroke (PwCS). Interventions that amplify self-generated movements may accelerate motor learning by enhancing a person's perception of movement errors. This method could potentially be applied to help PwCS improve walking balance. To this end, the investigators have developed a cable-driven robot to create a Movement Amplification Environment (MAE) during treadmill walking. The MAE challenges walking balance by applying lateral forces to the pelvis that are proportional in magnitude to real-time lateral center of mass (COM) velocity. Unlike a popular form of balance training that uses unpredictable perturbations to enhance reactive balance, training in a MAE targets anticipatory balance by developing predictive control mechanisms that are likely to persist when the training environment is removed (after-effects). The investigators believe that supplementing high-intensity gait training (the recommended practice to improve walking speed and distance) with a MAE will substantially enhance walking balance. Thus, the purpose is to evaluate the unique effects of MAE training on walking balance in PwCS and determine feasibility of conducting high-intensity gait training in a MAE. Specific Aims: Aim 1: To evaluate gait patterns PwCS adapt during and immediately following walking practiced in two balance-challenging training environments: MAE and unpredictable lateral perturbations. Aim 2: To establish feasibility of high intensity gait training in MAE the investigators will evaluate cardiovascular intensity during gait training interventions performed in either a natural unmodified environment or a MAE. Approach: Aims 1: 15 PwCS will participate in a single-day experiment evaluating gait biomechanics (COM dynamics and stepping patterns) during and immediately following treadmill walking performed in a MAE or while receiving frequent unpredictable lateral perturbations. Outcomes will assess if changes in gait patterns to maintain stability persist immediately following exposure to either of the balance-challenging environments. Aim 2: 15 PwCS will participate in two high-intensity gait training sessions. One session will be performed in a natural unmodified environment, the other in a MAE. The investigators will quantify differences in mean heart rate (HR) between the two sessions and whether mean HR is in the target high-intensity range of 70-85% of maximum HR. Impact: This project will identify if and how PwCS uniquely adapt locomotor strategies following exposure to balance challenging environments and evaluate feasibility of administering high-intensity gait training in a MAE. Training walking balance of PwCS in a MAE by amplifying their own self-generated movements is a radical departure from current practice and could substantially enhance walking balance. Successful outcomes will motivate a future randomized controlled trial assessing the efficacy of MAE training to enhance walking balance in PwCS.