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Abstract

Persons with spinal cord injury (SCI) often suffer from orthostatic hypotension (marked reduction in blood pressure upon assuming an upright posture) and exercise may assist with its treatment by improving cardiovascular health and autonomic regulation. Hybrid exercise (concurrent movement of the arms and legs) promotes enhancements in venous return, ventricular filling, and cardiorespiratory function. However, limited research has evaluated the effects of hybrid exercise on orthostatic tolerance. Accordingly, this study evaluated the effects of arm and hybrid exercise on orthostatic response and on cardiorespiratory function during peak exercise. Additionally, the effects of spinal cord lesion level were examined. Asymptomatic persons with SCI (C4-T6) and age- and gendermatched able-bodied controls participated in four testing days. The first two testing days examined participants’ orthostatic tolerance following rest followed by a peak arm cycle or hybrid exercise test (in random order). The final two testing days assessed the acute effects of steady state arm and hybrid exercise on orthostatic response (in random order). There was no significant decrease (p=O.07) in middle cerebral artery blood velocity upon assuming the upright position following a bout of hybrid steady state exercise in participants with SCI (67.2 ± 18.8 to 61.8 ± 14.8 cm s-1, respectively). Hybrid exercise resulted in significantly (p