Inclusion Criteria:  age 18 and 75 years (the latter to reduce likelihood of heart disease) medical clearance to participate lesion at or below C2 and above L5 with non-progressive etiology classified as motor-incomplete with visible volitional leg movement injury greater than 6 months ability to advance one step overground without human assistance  Exclusion Criteria:  Concurrent severe medical illness (i.e., infection, cardiovascular disease, ossification, recurrent autonomic dysreflexia, unhealed decubiti, and history of pulmonary complications) Pregnant women because of the unknown affects of AIH on pregnant women and fetus History of seizures, brain injury, and/or epilepsy Undergoing concurrent physical therapy Diabetes Cirrhosis Caffeine and/or NSAID allergies or intolerances