Undergraduate Honors Theses

Thesis Defended

Spring 2019

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Integrative Physiology

First Advisor

Douglas R. Seals

Second Advisor

Mark R. Opp

Third Advisor

Christy L. Fillman

Abstract

Aging is associated with increases in systolic blood pressure (SBP) and impaired vascular function, largely driven by arterial stiffening and adverse arterial remodeling, which increase risk of cardiovascular diseases (CVD). Passive heat therapy—chronic use of hot baths and sauna—is associated with lower CVD risk. However, it is unknown if heat therapy improves vascular function in healthy middle-aged and older (MA/O) adults. Purpose: To determine if passive heat therapy, via hot water immersion, reduces SBP, arterial stiffness, and promotes beneficial arterial remodeling in MA/O adults. Methods: Twelve healthy MA/O men and post-menopausal women (57-76yrs) participated in thirty 60-minute sessions (3-4x/wk) of either hot (40.5°C, n=7, 3M/4F, 66±2yrs) or thermoneutral (36°C, n=5, 1M/4F, 66±3yrs) water immersion. Ultrasound- and tonometry-based measures of vascular function and structure were measured at baseline and 24-72h after the last water immersion session. Data are mean±SEM. Results: Heat therapy reduced resting brachial SBP (131±4 vs. 122±5mmHg, P=0.03) and common carotid artery intima media thickness (0.70±0.02 vs. 0.65±0.02mm, P=0.02) and increased superficial femoral artery diameter (7.85±0.34 vs. 8.27±0.37mm, P=0.02). Aortic stiffness, measured by carotid-femoral pulse wave velocity, decreased in 5 out of 7 subjects, but there was no significant reduction in the group overall. No changes were observed in other measures of arterial stiffness or in any variable for the sham group (all P>0.05). Conclusion: Passive heat therapy robustly reduces resting SBP and promotes beneficial arterial remodeling in healthy MA/O adults, suggesting heat therapy may be an effective non-pharmacological lifestyle intervention for reducing CVD risk with aging.

Available for download on Tuesday, September 22, 2020

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