Inclusion Criteria- age 50-70,
- stroke within the past 6 to 24 months,
- residual paresis in the lower extremity (Fugl-Meyer Lower Extremity motor score <34),
- ability to walk without assistance and without an ankle foot orthotic (AFO) on the treadmill 30 seconds at speeds ranging from 0.3 - 0.8 m/s, and
- provision of informed consent.
- In addition, all subjects who meet criteria for the training portion must complete an exercise tolerance test and be cleared for participation by the study cardiologist.
Exclusion Criteria- Unable to ambulate at least 150 feet prior to stroke, or experienced intermittent claudication while walking;
- rating on Modified Ashworth Scale 3 at the knee or ankle;
- limited lower extremity range of motion of the knee (passive flexion Range of Motion [ROM] < 90); hip (inability to achieve neutral 0 hip extension); or ankle (inability to achieve 0 of active dorsiflexion);
- history of congestive heart failure, unstable cardiac arrhythmias, hypertrophic cardiomyopathy, severe aortic stenosis, angina or dyspnea at rest or during activities of daily living (ADLs);
- History of chronic obstructive pulmonary disease (COPD) or oxygen dependence;
- Preexisting neurological disorders, dementia or previous stroke;
- History of major head trauma;
- Legal blindness or severe visual impairment;
- history of significant psychiatric illness
- Life expectancy <1 yr.,
- Severe arthritis or other problems that limit passive ROM;
- post-stroke depression (PHQ-9 10),
- History of deep vein thrombosis (DVT) or pulmonary embolism within 6 months;
- Uncontrolled diabetes with recent diabetic coma, or frequent insulin reactions;
- Severe hypertension with systolic >200 mmHg and diastolic >110 mmHg at rest;
- Previous or current enrollment in a trial to enhance motor recovery;
- Presence of non-magnetic resonance (MR) compatible implants, pregnancy or severe claustrophobia.