High Intensity Exercise in Incomplete SCI

Inclusion criteria * Individuals with motor incomplete SCI (AIS C or D) \> 12 mo. duration will be recruited to participate in the study, with further criteria including anatomical lesions between C1-T10.. * Participants will be between 18 and 75 years of age (note: while participants \> 50 yrs with subacute SCI have a reduced probability of functional ambulation 79, participants will already be ambulatory with only minimal or no assistance and in the chronic phase of rehabilitation, and prediction rules using age will not necessarily apply in this study). * All participants must be able to perform walking training with passive range of motion within the limits of normal locomotor function, including: 0-30 degrees ankle plantarflexion, knee flexion from 0 to 90 degrees, hip flexion to 0-90 degrees. Exclusion criteria: * Participants with body mass \> 400 lbs will be excluded, which is the highest limit for use of our motorized treadmill and safety harness systems. * Participants will be medically stable with medical clearance to participate, with absence of concurrent severe medical illness including: unhealed decubiti, existing infection, significant cardiovascular or metabolic disease which limits exercise participation, significant osteoporosis (as indicated by history of fractures following injury), active heterotrophic ossification in the lower extremities, known history of peripheral nerve injury in lower legs, history of traumatic brain injury, and history of pulmon…