Postexercise heat loss and hemodynamic responses during head-down tilt are similar between genders

We evaluated the hypothesis that during recovery from dynamic exercise in the 15 degrees head-down tilt (HDT) position, the attenuation of the fall in mean arterial pressure (MAP), cutaneous vascular conductance (CVC), and sweat rate, and the augmentation of the rate of esophageal temperature (T(es)) decay relative to the upright seated (URS) posture, would be different between males and females.

Fourteen subjects (seven males, seven females) performed two experimental protocols: 1) 15 min of cycle ergometry at 75% VO2peak and then 60 min of recovery in the URS posture; or 2) 15 min of cycle ergometry at 75% VO2peak and then 60 min of recovery in the 15 degrees HDT position. Mean skin temperature, Tes, CVC, sweat rate, cardiac output (CO), stroke volume (SV), heart rate (HR), total peripheral resistance (TPR), and MAP were recorded at baseline; end of exercise; 2 min, 5 min, 8 min, 12 min, 15 min, and 20 min after exercise; and every 5 min until the end of recovery (60 min).

During recovery from exercise, we observed significantly greater values for MAP, CVC, and sweat rate with HDT in comparison with the URS recovery posture (P

HDT attenuates the reductions in MAP, CVC, and sweat rate observed after exercise in a gender-independent manner, and this likely is attributable to a nonthermal baroreceptor influence.