Acute Intermittent Hypoxia on Spinal Plasticity The objective of this study is to examine the effects of repeated episodes of mild acute intermittent hypoxia (AIH) on motoneuron activity in persons with incomplete spinal cord injury (SCI). In particular, we will quantify the effects of repeated exposure to AIH on limb muscle activity, and determine if changes in the observed muscle responses are accompanied by enhanced voluntary torque strength and walking performance. If true, such changes may indicate hypoxia-induced spinal plasticity resulting in functionally useful enhancement of motor output. Findings from this project could offer new insight into a possible mechanism of neuromodulation of spinal motoneuron pools and recovery of neuromotor function following SCI.