Blood Pressure Regulation Following Post-Exercise Heat Exposure

Cardiovascular adjustments after exercise, including temporary reductions in arterial blood pressure, vasodilation, and decreased baroreflex sensitivity likely mediate many of the vascular benefits of repeated exercise training. Hot water immersion has similarly been shown to decrease arterial pressure in both acute and chronic interventions, but it is unknown how post-exercise hot water immersion alters the cardiovascular response to exercise. The purpose of this study was to examine changes in blood pressure (BP), cardiac output (Q), peripheral resistance (TPR), and spontaneous cardiovagal baroreflex sensitivity (BRS) following aerobic exercise with or without post-exercise hot water immersion (HWI). Five healthy individuals (2M, 3F; Age: 23±4y; BMI: 21±2) completed two matched exercise bouts (7km of self-paced treadmill running with 8 x 0.4km high-intensity intervals) one week apart, and either rested for 30 min post-exercise (Control; CON) or submerged to the waist in 40°C water for 30 minutes (HWI). Brachial BP, Q, TPR, and BRS were measured in the supine position using the Finapres Nova autonomic testing suite pre-exercise and 30 min post-exercise (after Con or HWI treatment). Both systolic and diastolic BP declined more following post-exercise HWI compared to post-exercise CON (Systolic Pre = 124 ± 4 Post-HWI = 118 ± 3; Post-CON = 121 ± 2mmHg; Diastolic Pre = 70 ± 1; Post-HWI = 65 ± 2; Post-CON = 70 ± 3 mmHg). These decreases in BP with HWI appear related to a reduced Q (Pre = 5.2 ± 0.9; Post-HWI = 4.2 ± 0.4 L/min) and decreased TPR (Pre = 0.73±0.35; Post-HWI = 0.46±0.09 mmHg*min/L). In contrast, BRS did not change following post-exercise HWI (Pre = 9.2 ± 1.8; Post-HWI = 9.1 ± 2.3 ms/mmHg). These results indicate that post-exercise HWI augments the hypotensive response to exercise through reductions in both Q and TPR and may provide additional benefit for individuals who engage in exercise for cardiovascular health. Supported by the Rhode Island Institutional Development Award (IDeA) Network of Biomedical Research Excellence under grant number P20GM103430. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.