Study 1: Brachial artery flow-mediated dilation (FMD) using ultrasonography is used as a surrogate measure of coronary artery function. The purpose of this study was to i) assess the reliability of the PhD student in the use of ultrasonography to measure endothelial vasomotor function, and ii) develop and validate a custom-designed software to measure arterial diameter. The sonographer demonstrated excellent reliability in FMD assessment. Compared to in-built ultrasound calipers, the custom-designed software was shown to be a valid measure of arterial diameter. Study 2: This study evaluated the physiological and vascular responses to self-regulated exercise (SRE) and high-intensity interval training (HIIT) in individuals with cardiovascular disease. Physiological and perceptual responses were significantly higher in response to HIIT than SRE. There was no change in FMD in either group following exercise. Study 3: This study compared the effects of 4 weeks of traditional cardiac rehabilitation and 4 weeks of HIIT on the physiological and perceptual responses, endothelial function, and blood lipids in individuals with CVD. Treadmill time to exhaustion and percentage change in FMD were significantly higher in the HIIT group at week 4 than week 1.