Cardiovascular autonomic consequences of spinal cord injury, cardiovascular disease risk, and exercise adjuncts

Spinal cord injury SCI is a devastating, life-changing event that impacts motor, sensory, and autonomic function. Cardiovascular disease CVD, a secondary complication of SCI, has an earlier onset and faster progression following SCI and is the leading cause of morbidity and mortality. Traditional CVD risk factors obesity, blood pressure, cholesterol etc. are negatively impacted following SCI. Additionally, injury characteristics level, severity, and duration of injury and other secondary complications of SCI neuropathic pain, poor mental health, and exercise intolerance may contribute to the increased CVD burden after SCI. In this thesis I examined the impact of SCI characteristics and secondary complications on CVD risk and investigated the efficacy of exercise adjuncts following SCI. In Chapter 2, I aimed to identify key markers of obesity, injury characteristics, and autonomic function relating to CVD risk and establish population-specific cut-points for detection and risk management. I confirmed waist circumference as a practical, effective measure of CVD risk, and suggested a lower cut-point relative to the general population. Additional cut-points are suggested for injury characteristics and autonomic function. I expanded this work in Chapter 3 by examining the relationships between two non-traditional CVD risk factors – neuropathic pain and mental health – with cardiovascular autonomic function and CVD risk following SCI. Poor mental health was associated with increased CVD risk, while neuropathic pain was more prevalent in those with more intact cardiovascular function. In Chapter 4, I conducted a systematic review of two exercise adjuncts, passive lower limb movement and passive heat therapy, and found they were safe and efficacious in producing an exercise-like cardiovascular response. Finally, in Chapter 5, I conducted an experiment to test the safety of a prototype passive cycling wheelchair attachment and its efficacy to produce an exercise response and acutely improve cardiovascular function. While safety ratings were high and stroke volume and heart rate were increased, accessibility and usability need to be improved. The research conducted in this thesis helps to further our understanding of CVD risk following SCI, provides standards to increase detection of individuals at-risk for CVD, and offers evidence and options for mitigating CVD progression through exercise adjuncts.