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UBC Theses and Dissertations

The impact of exercise on cardiorespiratory fitness and cardiovascular health in individuals with cervical and upper-thoracic spinal cord injury Alrashidi, Abdullah Alhawah S.

Abstract

Spinal cord injury (SCI) leads to motor, sensory, and autonomic dysfunctions. Cardiovascular disease (CVD) is the leading cause of mortality and morbidity following SCI, higher level of injury and more severe SCI increases this risk. Individuals with SCI experience multiple CVD risk factors including reduced cardiorespiratory fitness (CRF), physical inactivity, and cardiometabolic syndrome. In uninjured individuals, evidence supports the positive effects of exercise on these CVD risk factors. This thesis examined the effect of exercise modalities on CVD risk factors after SCI. Adult participants with motor complete SCI between the fourth cervical and sixth thoracic spinal segments were assigned to 24 weeks of active arm exercise or passive leg exercise training three times per week. Outcome measures were collected before and after training completion; with arterial stiffness measured following 12 weeks of training. Research results are presented in four studies. First, a scoping review of the SCI literature investigated and critiqued common peak oxygen uptake (V̇O2peak) averaging strategies and V̇O2peak attainment criteria. The time-interval method was the most common averaging strategy, and 52% of studies reported 30-second averaging. Second, I examined the association between V̇O2peak and echocardiographic measures and found no association between these measures. Third, in a multicenter randomised clinical trial, I examined the effect of the above-mentioned exercise modalities on arterial stiffness, CRF, and cardiometabolic measures. Arm exercise improved CRF; whereas neither exercise modality affected arterial stiffness or cardiometabolic measures. Fourth, a crossover design examined the effect of the same exercise modalities on multiple cardiovascular measures following at least a 6-month washout period. Arm exercise improved CRF, increased left ventricular (LV) mass, and improved free fat mass. Overall, results from the scoping review highlighted the importance of standardized exercise testing methodology to ensure comparability between studies. The findings emphasized on the importance of performing structured exercise to improve CRF. Apart from the underpowered trials secondary to small sample sizes, arterial stiffness, cardiometabolic measures, LV functions may have limited responses to exercise in the SCI population. This may suggest that the exercise training employed in this thesis was insufficient to provide enough stimulus to induce changes in these measures.

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