Double-Blinded, Placebo-Controlled Trial Of Midodrine For Exercise Performance Enhancement In Tetraplegia:A Pilot Study

BACKGROUND/OBJECTIVE: Spinal cord injury (SCI) impairs cardiovascular autonomic responses to exercise and, depending on the level of injury, may result in hypotension and pathologic fatigue with exertion. Other clinical populations with sympathetic regulatory dysfunction, but without skeletal muscle paralysis, exhibit similar signs and symptoms. Their ability to engage in physical activity improves with elevation of blood pressure through pharmacologic treatment: Midodrine, an oral alpha-sympathomimetic agent, has been shown to be safe and efficacious for this purpose. Use of this medication in individuals with SCI merits investigation. METHODS: Double-blind, placebo-controlled, randomized, crossover, within-subjects protocol. Four participants with chronic, motor-complete injuries from C6 to C8 underwent 4 peak exercise tests (PXT) using a wheelchair ergometer, following administration of midodrine, 5 mg, 10 mg, and placebo, in random order. Heart rate, blood pressure, oxygen consumption (VO2), and perceived exertion were measured. RESULTS: Treatment with midodrine, 10 mg, was associated with elevated systolic blood pressure during peak exercise in 3 participants. Two participants showed a concurrent decrease in perceived exertion and increase in VO2. No adverse effects of midodrine were evident. CONCLUSION: Midodrine enhances exercise performance in some individuals with SCI, similar to other clinical populations with cardiovascular autonomic dysfunction.