Acute Intermittent Hypoxia on Leg Function Following Spinal Cord Injury

The purpose of this study is to determine how the nervous system controlling leg muscles is altered following spinal cord injury and how they may be affected by brief periods of low oxygen inhalation over time. The investigators hypothesize: * Acute intermittent hypoxia (AIH) exposure will increase maximum voluntary leg strength in persons with incomplete cervical spinal cord injury (SCI) * AIH exposure will increase multijoint reflex excitability of leg muscles in persons with incomplete cervical SCI * AIH exposure will increase walking performance in persons with incomplete cervical SCI