Change to Reflect What Was Done and reason Changes Were Made.

The purpose of this study is to determine (1) if a specific breathing treatment (intermittent hypoxia) can promote changes in breathing function and (2) if pairing breathing treatments (hypoxia) with locomotor training can enhance the benefits of walking recovery observed with locomotor training alone (without breathing treatments).

Spinal cord injury (SCI) is a very disabling health problem. Paralysis and paresis of limb and trunk muscles are major consequences of SCI and result in the inability to walk or difficulty walking. The most commonly stated goal by individuals with SCI during rehabilitation is the desire to walk again. Locomotor training (LT) that uses a body-weight support system and treadmill (BWST) is a task-specific rehabilitation intervention that allows practice of walking at normal speeds while loading the lower extremities, facilitating upright posture, and hip extension. Substantial improvement in ambulation can occur following locomotor training (LT) in individuals with motor incomplete spinal cord injury (iSCI). Despite these advances in activity-dependent rehabilitation, a need exists for defining complementary strategies that further amplify endogenous neuroplasticity. The proposed study will assess the therapeutic potential of (1) a respiratory training intervention (acute intermittent hypoxia, or AIH) on breathing function and (2) a combined locomotor (LT) and respiratory (AIH) training intervention for enhancing walking recovery.

Inclusion Criteria:

• Adults at least 18 years of age
• At least 12 months post-incomplete spinal cord injury (I-SCI), including but not limited to the following syndromes: Brown Sequard and Central Cord Syndromes
• Upper motor neuron lesion (with upper motor neuron signs (i.e. presence of clonus, spasms, and/or hyperreflexia))
• A diagnosis of first time SCI including etiology from trauma, vascular, or orthopedic pathology
• Resting oxygen saturation (SpO2) levels of 95-99%
• Individuals who ambulate independently, with an assistive device, or who can walk when provided manual assistance
• Persons using anti-spasticity medication must maintain stable medication dosage during the study
• Able to give informed consent.
• Medical approval by individual's physician

Exclusion Criteria:

• Current participation in a rehabilitation program/research protocol that could interfere or influence the outcome measures of the current study
• History of congenital SCI (e.g. myelomeningocele, intraspinal neoplasm, Frederich's ataxia) or other degenerative spinal disorders (e.g. spinocerebellar degeneration, syringomyelia) that may complicate the protocol
• Inappropriate or unsafe fit of the harness due to the participant's body size and/or joint contractures or severe spasticity that would prohibit the safe provision of either training modality.
• Severe spasticity that would prohibit the safe provision of training.
• Pregnancy - all women of childbearing age will be required to undergo pregnancy testing prior to enrollment
• Unstable medical condition that could interfere with safety during participation in study (i.e. symptomatic cardiopulmonary complication, osteoporosis, contractures or other significant medical complications that would prohibit or interfere with testing of walking function and training or alter compliance with a training protocol)