Presenter: Andrew Jeckell
Mentors: Christopher Minson and Vienna Brunt, Human Physiology
Poster: 31
Major: Post-baccalaureate
Reactive hyperemia is a transient increase in blood flow that occurs following a period of ischemia (e.g. arterial occlusion) and is indicative of microvascular health. Regular exercise is a critical preventive measure in maintaining reactive hyperemia; however, consistent exercise is difficult or impossible for some people. Recent evidence suggests chronic passive heat therapy (CHT) may result in improvements to cardiovascular health similar to exercise. To examine the effects of 8 weeks of CHT on forearm post-occlusive reactive hyperemia, six healthy university students (21 ± 1 years) underwent hot water immersion 4-5 times per week to maintained rectal temperature of 38.5°C
for 1 hour per session. Before and after 8 weeks of CHT, brachial artery blood flow was measured via Doppler ultrasonography for 3 minutes following a 5-minute forearm arterial occlusion. Data presented as mean ± SE vascular conductance (VC, blood flow divided by mean arterial pressure). In preliminary subjects, change in peak VC from baseline, indicating structural microvascular changes, increased following CHT from 1.77 ± 0.24 to 2.26 ± 0.20 ml/ min/mmHg (p = 0.09). Area-under-the-curve of the hyperemic response, indicating functional changes, increased from 59.7 ± 9.0 to 111.9 ± 13.0 sec.ml/min/mmHg (p = 0.11). CHT appears to produce structural and functional microvasculature changes comparable to that of exercise, and could potentially serve as an alternative method for improving cardiovascular health.