Inclusion Criteria:  All participants  - age 18-30 years old.  Participants with spinal cord injury  Adult onset, traumatic spinal cord injury. Time since injury 1 year, in an effort to limit baroreflex desensitization. American Spinal Injury Association Impairment Scale, A, to limit potential confounders. Neurological level of injury, T1-T6, as defined by the International Standards for Neurological Classification of Spinal Cord Injury.  Exclusion Criteria:  History of cardiovascular disease, hypertension, neurologic disorders (with exception of spinal cord injury), or diabetes. Women who are pregnant or lactating. Currently taking blood thinners. Taking anti-hypertensive or other medication that could influence any of the dependent autonomic variables.