The effects of novel hybrid exercise rehabilitation on cardiovascular function and orthostatic tolerance in individuals with spinal cord injury

• Main Author: Wong, Shirley Candice
• Language: English
• Published: University of British Columbia 2009
• Online Access: http://hdl.handle.net/2429/5531

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<O.05) greater cardiorespiratory requirements throughout incremental exercise in comparison to arm ergometry in all groups. The average peak oxygen uptake (across all groups) was 21 ± 9 vs. 19 ± 7 mLkgmin-1,for hybrid exercise vs. arm ergometry, respectively. The average peak oxygen uptake (across all modes of exercise) was 24.9 ± 7.9 vs. 15.7 ± 4.2 mLkgmin-1,for able-bodied participants vs. participants with SCI, respectively. Furthermore, persons with paraplegia had significantly (p<O.05) higher oxygen uptake than persons with tetraplegia and the average peak oxygen uptake (across all modes of exercise) was 18.5 ± 3.7 vs. 12.9 ± 2.4 mLkg•min-1for these groups, respectively. Hybrid exercise improved cardiovascular response to an orthostatic challenge and promoted greater cardiorespiratory response in comparison to arm exercise in persons with Sd. Furthermore, lesion level of SCI affects responses to an orthostatic challenge and peak exercise.