Multimodal Exercises to Improve Leg Function After Spinal Cord Injury

A Hebbian Approach to Regaining Control of Spared Circuits in Spinal Cord Injury

Many people with spinal cord injury (SCI) retain at least some movement below their injury, but their muscles often have a 'mind of their own'. Typical exercise programs focus on keeping muscles strong and flexible, but don't usually focus on helping patients control their muscles. The investigators' exercise research study will compare two different programs with the specific goal of improving conscious control of patients' muscles below the injury. This study focuses on those with 'chronic' SCI - the injury occurred at least one year prior to enrolling.

This is a single center study taking place in the Bronx, NY.

The first phase of the study will be observational - the investigators will analyze which nerve connections might remain partially intact through the injury (even if the nerves aren't consciously controlled). Participants with all severity of SCI may participate in this first phase.

The second phase of the study will involve people who retain at least slight ability to move their legs and the ability to move the arms against gravity. Each person will undergo two different exercise rehabilitation strategies: weight-supported treadmill training; and balance training combined with skilled arm or hand exercises.

The investigators will compare the effects of these exercise programs on a variety of outcomes, including gait speed, balance, strength, and muscle activation in response to brain stimulation.

The investigators hypothesize that participants with chronic SCI undergoing combined balance/arm/hand training will show improved outcomes when compared to traditional gait or balance training.

Inclusion Criteria:

• Males or females age 21-65 years;
• SCI duration > 12 months;
• SCI level C2-T12;
• All SCI severity eligible for baseline testing;
• For exercise protocol, must have severity of Grade C or D on American Spinal Injury Association (ASIA) Impairment Scale, or volitional strength of at least 1/5 in two or more key lower extremity muscles, as well as at least 3/5 in both shoulder and elbow muscles;
• Able to tolerate upright position with support;
• Morphologically capable of fitting a weight-support harness and robotic treadmill system;
• Ability to give informed consent.

Exclusion Criteria:

• Unsuitable cognitive capacity as judged by the study physician;
• Diagnosis of neurological injury other than SCI, such as stroke, traumatic brain injury, or other neurological condition that the study physician considers to be exclusionary;
• Multiple spinal cord lesions;
• History of frequent autonomic dysreflexia;
• History of seizures;
• Use of medications that significantly lower seizure threshold, such as anti-psychotics, tricyclic antidepressants, amphetamines, and bupropion;
• History of implanted brain/spine/nerve stimulators, aneurysm clips, or cardiac pacemaker/defibrillator;
• Deep vein thrombosis in lower extremities of less than 6 months duration;
• Pregnancy;
• (Interventional phase only): Lack of detectable tibialis anterior motor evoked potential (MEP) at baseline even with active facilitation;
• (Interventional phase only): Pressure ulcers greater than stage 1 severity on the foot, ankle, knee and/or pelvic girdle;
• (Interventional phase only): Bone mineral density of the hip (proximal femur) T-score <3.5 standard deviations from age- and gender-matched normative data;
• (Interventional phase only): Any spasticity, contractures, or heterotopic ossification that result in inadequate range of motion of the shoulder, elbow, wrist, fingers, hip, knee, or ankle joints in the judgment of the study physician;
• (Interventional phase only): Inability to cooperate with instructions or unwilling to commit to daily training sessions for 3-4 days per week over 12-16 weeks;
• (Interventional phase only): A diagnosis of coronary artery disease that precludes moderate to intense exercise.