Inclusion Criteria:  Healthy individuals, ages 20 or older Healthy participants will be required to be medically stable Healthy participants are able to walk at least 10 meters independently at a comfortable speed without an assistive device The participants with a history stroke, ages 20 or older Unilateral first stroke of ischemic origin in the carotid artery distribution Unilateral first stroke of hemorrhagic origin in the carotid artery distribution Diagnosis of stroke at least 6 months prior to participation Free of major post-stroke complications (e.g., recurrent stroke, hip fracture, myocardial infarction) Living within the community The participants with a history stroke are able to ambulate 10 meters with or without assistive devices  Exclusion Criteria:  A history of any significant orthopedic problems A history of psychiatric or cognitive illness (e.g., bipolar affective disorder, psychosis, schizophrenia, attention deficits, cognitive deficits, or medication refractor depression) Neurological problems Stroke secondary to subarachnoid hemorrhage or posterior circulation stroke Not expected to live more than one year Comatose Unable to follow 3 step commands Amputation Poorly controlled diabetes (e.g., foot ulceration) Blind Progressive neurological diseases Comprehensive aphasia Medical instability Significant musculoskeletal problems Congestive cardiac failure Unstable angina Peripheral vascular disease Neuropsychiatric disorders (e.g., dementia, cognitive deficits, and severe depression)