Hemodynamics of Post-Exercise and Post-Passive Heat Stress Recovery Periods

Presenter(s): Cameron Colbert

Faculty Mentor(s): Christopher Minson & Michael Francisco

Oral Session 4 CQ

Recent research suggests that individuals exposed to heat stress chronically (e.g. sauna users) enjoy similar benefits as chronic exercisers. Many of exercise’s benefits are facilitated during the recovery phase, or the period of time following the cessation of exercise. By studying the cardiovascular responses during the recovery period following both heat stress and exercise, we can further explore clinically-relevant applications of heat therapy. This study seeks to compare the acute physiology of the recovery periods following exercise and hot water immersion (HWI). METHODS: 9 subjects (4 F, 5 M, age 22.4 ± 2.4 years) in random order exercised for 60 minutes at 60% VO2 peak and were immersed in 40.5oC water for 60 minutes on separate days. Measurements were made at baseline, during the interventions, and for 60 minute recovery period following both interventions. Heart rate, blood pressure, core temperature, and subjective measures were recorded every five minutes. Cardiac output, femoral and brachial artery hemodynamics were assessed using Doppler ultrasonography every 20 minutes. Skin blood flow was measured continuously during recovery. RESULTS: Brachial artery antegrade shear rate increased during HWI to a greater extent than exercise (p0.06). Skin blood flow following hot water immersion was significantly greater than that of post-exercise for the first 35 minutes of recovery (p<0.028). DISCUSSION: Many of the changes seen during the post-exercise recovery period that lead to beneficial cardiovascular adaptation are also seen during the post- immersion recovery period, suggesting hot water immersion may improve cardiovascular health.

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