Inclusion Criteria:  experienced unilateral stroke at least 6 months prior; voluntarily shoulder flexion of the affected arm 20 degrees with simultaneous elbow extension 10 degrees; moderate arm movement impairment (UE Fugl-Meyer Assessment > 21 but < 52 points; passive range of motion in paretic shoulder, elbow, wrist, thumb and fingers within 20 degrees of normal; 50-90 years of age; ability to communicate as per the therapists' judgement at baseline testing; ability to complete and pass an exercise tolerance test; 8) Box & Block test score of at least 3 blocks in 60 seconds with the affected arm.  Exclusion Criteria:  lesion in brainstem/cerebellum as these may interfere with visual-perceptual/cognitive skills needed for motor re-learning; presence of other neurological disease that may impair motor learning skills; orthopedic condition or impaired corrected vision that alters reaching ability (e.g., prior rotator cuff tear without full recovery); paretic arm pain that interferes with reaching; unable to understand or follow 3-step directions; severe cognitive impairment (MoCA score 17); severe aphasia; inability to read English, history of congestive heart failure, unstable cardiac arrhythmias, hypertrophic cardiomyopathy, severe aortic stenosis, angina or dyspnea at rest or during ADL's; Severe hypertension with systolic >200 mmHg and diastolic >110 mmHg at rest; History of COPD or oxygen dependence; History of DVT or pulmonary embolism within 6 months; Uncontrolled diabetes with recent weight loss, diabetic coma, or frequent insulin reactions; UBACC score < 15; and for brain stimulation procedures only: electronic or metallic implants; history of seizures; women of child bearing potential.