Baroreceptor influence on post-exercise warm thermal response thresholds.

Abstract

The role of baroreceptor modulation on the post-exercise esophageal temperature threshold for cutaneous vasodilation (ThVD) and sweating (Th SW) was investigated. Six subjects were randomly exposed to lower body positive pressure (LBPP) and to no lower body positive pressure (NoLBPP) following a No-Exercise (NoEx) and Exercise (Ex) treatment protocol. The Exercise treatment consisted of 15 min of cycling at 70% VO2max and the No-Exercise treatment consisted of 15 min upright resting. Immediately following either treatment, subjects were positioned within a LBPP box after which a whole body water perfused suit was used to regulate mean skin temperature to assess ThVD and ThSW. ThVD increased 0.34°C post-exercise from the NoEx/NoLBPP condition to the Ex/NoLBPP condition (P < 0.05). However, the post-exercise increase in ThVD was abolished in the Ex/LBPP condition. No differences in ThSW were measured among the 4 conditions. These data support the hypothesis that the observed elevated post-exercise ThVD is the result of baroreceptor unloading. The similarity in threshold responses for sweating onset suggests that the post-exercise ThSW is not sensitive to baroreceptor loading or unloading.