Autonomic Cardiovascular Control in Paralympic Athletes with Spinal Cord Injury

INTRODUCTION: Disruption of autonomic control after spinal cord injury (SCI) results in life-threatening cardiovascular dysfunctions and impaired endurance performance; hence, an improved ability to recognize those at risk of autonomic disturbances is of critical clinical and sporting importance. PURPOSE: The objective of this study is to assess the effect of neurological level, along with motor, sensory, and autonomic completeness of injury, on cardiovascular control in Paralympic athletes with SCI. METHODS: Fifty-two highly trained male Paralympic athletes (age, 34.8 ± 7.1 yr) from 14 countries with chronic SCI (C2-L2) completed three experimental trials. During trial 1, motor and sensory functions were assessed according to the American Spinal Injury Association Impairment Scale. During trial 2, autonomic function was assessed via sympathetic skin responses (SSR). During trial 3, cardiovascular control was assessed via the beat-by-beat blood pressure response to orthostatic challenge. RESULTS: Athletes with cervical SCI exhibited the lowest seated blood pressure and the most severe orthostatic hypotension (P < 0.025). There were no differences in cardiovascular function between athletes with different American Spinal Injury Association Impairment Scale grades (P > 0.96). Conversely, those with the lowest SSR scores exhibited the lowest seated blood pressure and the most severe orthostatic hypotension (P < 0.002). Linear regression demonstrated that the combined model of neurological level and autonomic completeness of SCI explained the most variance in all blood pressure indices. CONCLUSION: We demonstrate for the first time that neurological level and SSR score provide the optimal combination of assessments to identify those at risk of abnormal cardiovascular control. We advocate the use of autonomic testing in the clinical and sporting classification of SCI athletes.