Heat therapy may be an alternative or adjunct intervention to exercise training for improving cardiovascular function and health. However, its prescription must be refined in order to overcome the feasibility and tolerability issues associated with current whole-body heating modes. There is substantial evidence to support the beneficial effects of high doses (e.g., frequency, duration, and intensity) of heating typically achieved using whole-body modes, but there is limited knowledge on whether lower doses of heating administered through local hot water immersion of the limbs can still have an impact on vascular function. All studies were conducted in heathy young men and women. In the first study, we found that regardless of whether local heating was applied to the lower limbs up to the ankles or knees, upper limb endothelial function and lower limb arterial stiffness improved acutely. In the second study, we proceeded to prescribe ankle-level heating in a chronic intervention and compared its effects to that of moderate-intensity cycling exercise training. We observed no changes in endothelial function, but decreases in central arterial stiffness and increases in cardiorespiratory fitness in those who performed heat therapy and exercise training combined with heat therapy. In the third study, we evaluated the ability of acute vascular function responses to predict chronic vascular function responses with heating and exercise interventions, and found significant positive associations between the acute and chronic responses for absolute and relative brachial artery flow-mediated dilation and femoral-foot pulse wave velocity. These findings suggest that, in healthy young men and women, local heating through ankle-level hot water immersion can improve indices of cardiovascular function both acutely and chronically, alone or combined with exercise training. Further, acute responses may be used to determine an individual’s chronic responsiveness to a heat therapy and/or exercise training intervention. More research in larger, more diverse samples and with a longer duration of therapy and/or training should be conducted to determine if the results are replicable. / Dissertation / Doctor of Philosophy (PhD) / Regular participation in whole-body heat therapy can extend health and life span, but it is used infrequently because of a lack of feasibility from a cost, accessibility, and tolerability standpoint. This thesis explored whether local heat therapy in young healthy men and women would be effective for improving blood vessel health defined as endothelial function and arterial stiffness, both of which are linked to the risk of developing many chronic diseases. Furthermore, the effects of local heat therapy were compared to that of exercise training. We found that there were beneficial short- and long-term effects of lower limb hot water immersion that manifested in different areas of the body. Local heat therapy improved upper limb endothelial function and lower limb arterial stiffness immediately after a session, whereas with repeated exposure, it may have improved central arterial stiffness and cardiorespiratory fitness. Exercise training only had beneficial effects on the blood vessels when combined with heat therapy. Finally, short-term vascular responses can predict long-term vascular responses to both heat therapy and/or exercise training. Overall, our findings suggest that there may be some utility for local heat therapy to promote healthy blood vessels, but more work must be done to replicate our findings and explore its effects on other populations.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/28460 |
| Date | 15 June 2023 |
| Creators | Cheng, Jem L |
| Contributors | MacDonald, Maureen J, Kinesiology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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