Presenter: Kaitlin Livingston
Mentors: Christopher Minson and Vienna Brunt, Human Physiology
Poster: 44
Major: Human Physiology
Repeated bouts of exercise in the heat are known to decrease resting body core temperature (Tc), mean arterial pressure (MAP) and resting heart rate (HR). Although exercise in the heat produces these cardiovascular changes, it is currently unknown whether passive chronic heating provides the same benefits. Our research sought to examine the effects of passive chronic heating on resting Tc, MAP, and HR. Five sedentary, college-aged subjects (4 females, 1 male) were assigned to an 8-week hot water immersion program (4-5 sessions/week). Subjects were submerged to the clavicle in 40.5°C water until a rectal temperature (Tre) of 38.5°C was reached. Subjects maintained a Tre between 38.5-39.0°C during an hour of partial immersion. HR and Tre were measured with a HR monitor and rectal thermistor both at rest and at 5-minute intervals during the heat stress. MAP was measured on another day with brachial auscultation after ≥20 minutes of supine rest. Both resting MAP (81±1 vs. 76±2 mmHg, p=0.02) and resting Tre (37.4±0.5 vs. 36.8±0.4°C, p=0.03) decreased after 8 weeks of passive heat stress with no change in resting HR (63±5 vs. 63±6 beats/min, p=0.26). Chronic passive heat stress reduces resting MAP and Tre similarly to what is observed with exercise heat in the heat. This suggests that chronic passive heat stress could be used to benefit cardiovascular health similarly to exercise in the heat.