SCI Acute Intermittent Hypoxia and Non-Invasive Spinal Stimulation Combined With Gait Training

This is a single blind, sham controlled crossover trial that will evaluate the effectiveness of acute intermittent hypoxia therapy (AIH) combined with transcutaneous (non-invasive) spinal cord stimulation on gait and balance function for individuals after spinal cord injury.

OBJECTIVES:

* To determine whether acute intermittent hypoxia therapy (AIH) combined with transcutaneous spinal cord stimulation during ambulation training modulates spinal locomotor networks in individuals with spinal cord injury
* To determine whether acute intermittent hypoxia therapy (AIH) combined with transcutaneous spinal cord stimulation during ambulation training improves locomotor function in individuals with spinal cord injury
* To determine whether acute intermittent hypoxia therapy (AIH) combined with transcutaneous spinal cord stimulation during ambulation training improves symmetry of gait in individuals with spinal cord injury
* To determine whether acute intermittent hypoxia therapy (AIH) combined with transcutaneous spinal cord stimulation during ambulation training improves standing posture and balance in individuals with spinal cord injury
* To determine whether ambulation efficiency (improved cardiovascular conditioning) improves with a combination of AIH, transcutaneous spinal cord stimulation and ambulation training in individuals with spinal cord injury

Eligibility Criteria:
Inclusion Criteria:

* Participants have been diagnosed with a spinal cord injury below level C2
* ASIA Impairment Scale Grade A-D
* Participants are 18 years of age or older
* Participants are at least 6 months post spinal cord injury
* Participants with paraplegia or tetraplegia secondary to a single spinal cord injury
* Participants are able to provide informed consent
* Participants are not currently receiving regular physical therapy services

Exclusion Criteria:

* Individuals less than 18 years of age
* Individuals less than 6 months post spinal cord injury
* Individuals with ataxia
* Individuals with multiple spinal cord injury history
* Pregnancy or nursing
* Pacemaker or anti-spasticity implantable pumps
* Active pressure sores
* Unhealed bone fractures
* Peripheral neuropathies
* Painful musculoskeletal dysfunction due to active injuries or infections
* Severe contractures in the lower extremities
* Active urinary tract infection
* Clinically significant depression, psychiatric disorders, or ongoing drug abuse
* Diagnosed with any of the following medical conditions: congestive heart failure, cardiac arrhythmias, uncontrolled hypertension, uncontrolled diabetes mellitus, chronic obstructive pulmonary disease, emphysema, severe asthma, previous myocardial infraction, or known carotid/intracerebral artery stenosis
* Individuals with a tracheostomy or who utilize mechanical ventilation.
* Individuals who are currently enrolled in another interventional research study or in therapy related to upper extremity function.
* Participants will be excluded if they have had a botulinum toxin injection to lower extremity musculature within the last 3 months. Participants will need to refrain from lower extremity botulinum toxin injections for the duration of the study. If participants wean off antispasticity medications to successfully complete the responsiveness to AIH screening session, they will need to refrain from the medications for the duration of the study.
* Documented sleep apnea.
* Orthopedic injuries or surgeries that would impact an individual's ability to use the lower extremity.
* Traumatic brain injury or other neurological conditions that would impact the study.
* Blood hemoglobin levels less than 10g/dL.

We will not include the following populations:

* Adults unable to consent, unless accompanied by a legally authorized representative.
* Individuals who are not yet adults (infants, children, teenagers)
* Pregnant women
* Prisoners