Inclusion Criteria:

• Skeletal maturity and ability to sign informed consent (>18 years)
• Non-ventilator dependent paralysis resulting from injuries such as: mid cervical/thoracic (C4 or below) spinal cord injuries, poststroke hemiparesis, TBI, or MS, affecting the trunk and/or lower limbs
• Innervated and excitable lower extremity and trunk musculature
• Adequate social support and stability
• Willingness to comply with follow-up procedures
• Time post injury greater than six months
• Appropriate body habitus (height and weight within acceptable limits as determined by study physician)
• Neurologically stable as determined by a physician

Exclusion Criteria:

• Non-English speaking
• Females who are pregnant
• Current pressure injuries that would be exacerbated by study activities
• Severe contractures or uncontrolled spasticity of any major joint of the upper or lower extremities that results in a fixed deformity that would interfere with study activities
• History of spontaneous fractures or other evidence of excessively low bone density
• History of vestibular dysfunction, balance problems, or spontaneous falls
• Acute and or/untreated orthopedic problems that would prevent a participant from weight bearing or exercising such as a dislocation or fracture.
• Acute and/or chronic problems left untreated or not controlled that would put a participant at risk by using stimulation such as cardiac abnormalities, immunological/pulmonary/renal/circulatory compromise, diabetes or hypertension
• Presence of a demand pacemaker or cardiac defibrillator
• Any other medical or psychological condition that would be a contraindication
• Current pressure ulcers
• Significant range of motion limitations that would compromise study activities
• Body habitus that would compromise study activities