Decreased core-to-skin heat transfer in mild essential hypertensives exercising in the heat.

In previous reports (1,2) we examined the physiological responses of normotensive and essentially hypertensive men to steady state leg exercise (at 40% V02max) in a warm (38 degrees C dry-bulb, 28 degrees C wet-bulb) environment. Those results are reviewed. Additionally, in this paper we report relative core-to-skin heat transfer (HT) characteristics of these two groups, matched for age, aerobic fitness, and body composition, but differing in resting blood pressure. Forearm skin blood flow (as measured from changes in total forearm blood flow) was relatively reduced in the hypertensives. This resulted in a similar (but slightly compensated) reduction in HT, e.g., at minute 30, the hypertensives had 81% less skin blood flow and 56% less HT than their normotensive counterparts. This finding has important implications for unmedicated mild hypertensives exercising or working in hot environments.