Spinal Cord Stimulation and Training

Inclusion Criteria: Healthy Volunteers * Age between 16 and 65 years old * Healthy people with no major comorbidities of any organ system Exclusion Criteria: Healthy Volunteers * Subjects younger than 16 or older than 65 years old * Subjects not providing consent or not able to consent * Subjects with any acute or chronic pain condition * Subjects with any acute or chronic disease of a major organ system * Use of analgesics within 24 hours prior to study period * Use of caffeine with 3 hours of study appointment Inclusion criteria: Participants with spinal cord injury (SCI) * Age between 16-65 years old * Traumatic SCI C4-T9 level, incomplete (ASIA C or D) * at least 1 year post injury * Stable medical condition * difficulty independently performing leg movements in routine activities * able to follow simple commands * able to speak and respond to questions Exclusion criteria: Participants with spinal cord injury (SCI) * Subjects younger than 16 or older than 65 years old * Not willing or able to provide consent * Any acute or chronic pain condition * Any acute or chronic disease of a major organ system * Use of analgesics within 24 hours prior to study appointment * Use of caffeine with 3 hours of study appointment * Presence of tremors, spasms and other significant involuntary movements * Etiology of SCI other than trauma * Concomitant neurologic disease traumatic brain injury (TBI) that will significantly impact the ability to follow through on study directions, multiple sclerosis (MS), stroke or peripheral neuropathy) * History of significant medical illness (cardiovascular disease, uncontrolled diabetes, uncontrolled hypertension, osteoporosis, cancer, chronic obstructive pulmonary disease, severe asthma requiring hospitalization for treatment, renal insufficiency requiring dialysis, autonomic dysreflexia, etc). * Severe joint contractures disabling or restricting lower limb movements. * Unhealed fracture, contracture, pressure sore, urinary tract infection or other uncontrolled infections, other illnesses that might interfere with lower extremity exercises or testing activities * Depression, anxiety, or cognitive impairment * Deficit of visuospatial orientation * Sitting tolerance less than 1 hour * Severe hearing or visual deficiency * Miss more than 3 appointments without notification * Unable to comply with any of the procedures in the protocol * Botulinum toxin injection in lower extremity muscles in the prior six months * Any passive implants (osteosynthesis material, metallic plates or screws) below T9. * Any implanted stimulator in the body (pacemaker, vagus nerve stimulator, etc.) * History of alcoholism or another drug abuse * Pregnancy (or possible pregnancy) * Having an Intrathecal Baclofen Therapy Pump (ITB pump) * History of epilepsy