Inclusion criteria:  Aged at least 18 Premorbidly independent If post-stroke, mild to moderate impairment determined by standard practices per the physical therapist Able to continuously walk for 30 minutes If post-stroke, reduced knee flexion during walking relative to unimpaired side If post-stroke, hemiparesis Ability to provide informed consent  Exclusion criteria:  No history of serious lower limb musculoskeletal injury No functionally relevant osteoarthritis and weight-bearing restrictions No functionally relevant polyneuropathy No functionally relevant cognitive impairment No functionally relevant vision impairment