The effects of high-intensity exercise on cardiometabolic health in persons with spinal cord injury

: (Alternative Format Thesis)

Abstract

Individuals with a spinal cord injury (SCI) are at an increased risk of developing cardiovascular disease (CVD) in comparison to the general population. Despite convincing evidence in non-injured humans that high-intensity interval training (HIIT) can offer similar or superior metabolic advantages to moderate-intensity continuous training (MICT), the efficacy of this form of exercise has yet to be comprehensively studied in individuals with SCI. The aim of this thesis was to determine the acute and chronic training effects of upper-body high-intensity exercise on markers of CVD risk in persons with SCI. In Chapter 4, a systematic review of the available peer-reviewed research concluded that upper-body aerobic exercise training was effective at reducing waist circumference and improving hepatic insulin sensitivity. However, it was not sufficient to improve fasting glycaemia, the blood lipid profile, or resting blood pressure when performed in isolation. The addition of upper-body resistance training appeared to elicit positive changes in the lipid profile. In Chapter 5, an acute bout of upper-body high-intensity interval exercise (HIIE) or moderate-intensity continuous exercise (MICE) performed in the fasted state had no effect (in comparison to a no-exercise control condition) on subsequent postprandial glucose, insulin, or triglyceride responses in individuals with chronic paraplegia. In Chapter 6, an acute bout of iso-energetic HIIE or MICE performed the evening prior to a mixed macronutrient meal test had no effect (in comparison to a no-exercise control condition) on postprandial lipaemia in healthy non-injured adults. Finally, in Chapter 7, a randomised controlled trial found that six-weeks of home-based upper-body HIIT improved fasting insulin resistance and physical capacity, with a trend towards an improvement in postprandial insulin sensitivity in individuals with chronic paraplegia. Further, very high compliance rates were reported, and it was demonstrated that home-based upper-body HIIT is feasible, safe, and enjoyable for this population. An increase in low-density lipoprotein cholesterol was observed following upper-body HIIT, although the reason for this was unclear. This thesis has shown that an acute bout of upper-body exercise, irrespective of timing or intensity, does not appear to improve postprandial metabolism. However, upper-body HIIT is feasible and enjoyable for individuals with chronic paraplegia and leads to an increase in fitness. Additionally, unlike upper-body MICT, this form of exercise may also improve postprandial measures of insulin sensitivity.

Date of Award	12 Oct 2022
Original language	English
Awarding Institution	University of Bath
Supervisor	James Bilzon (Supervisor) & Dylan Thompson (Supervisor)