Doctor of Philosophy (PhD)



Document Type



The effects of stretching and yoga on the cardiovascular and muscular systems are still being discovered and can be assessed non-invasively. The purpose of this dissertation was to examine the non-invasive markers of stretching and yoga on the metabolic, cardiovascular, and muscular systems. A series of three studies were conducted to gain insight into how stretching and yoga influence the body and if there are any potential differences between them.

The first study aimed to determine if stretching would influence fiber type and motor unit recruitment. An acute bout of stretch exercise was performed immediately before a biking exercise session while metabolic rate was measured. There was a change in the range of motion, but results indicated there was not a stretch effect on the metabolic crossover point.

The second study examined the feasibility and effectiveness of an 8-week yoga intervention with two local fire departments. Participants performed two specialized 60-minute yoga classes per week at their training center. Increases in full body flexibility and a decrease in waist circumference were observed from pre- and post-intervention testing measures. Together these data suggest that yoga may be an acceptable modality to improve health in firefighters.

The last study expanded the outcomes to examine the cardiovascular and muscular effects from an acute session of stretch and yoga exercise. The aim of this study was to determine what role stretching plays in the yoga exercise. Measures of heart rate variability, arterial stiffness, vascular function, tissue oxygenation, and range of motion were taken pre- and post-exercise. Results from this study showed both yoga and stretch exercise sessions increased sit-and-reach range of motion, enhanced muscular oxygenation, and stimulated the sympathetic nervous system (SNS) through an increased normalized low frequency (LFnu) to normalized high frequency (HFnu) ratio and a decreased NN50 (number of beat-to-beat (N-N) intervals that were greater than 50ms apart) that did not return to baseline within 60-minutes post-exercise. Yoga exercise had a greater impact on activating the SNS frequency heart rate variability (HRV) measures, while stretch exercise had an impact on the SNS HRV time domain measures.

Committee Chair

Johannsen, Neil M.



Available for download on Monday, April 07, 2025