Effects of exercise-heat acclimation on fluid, electrolyte, and endocrine responses during tilt and +Gz acceleration in women and men.

Plasma fluid, electrolyte, protein, renin, and vasoactive hormone (epinephrine, norepinephrine, vasopressin) responses were measured in six women (21-23 yr) and four men (21-38 yr) before and immediately following an orthostatic tolerance test (70 degrees head-up tilt) and a +Gz (head-to-foot) acceleration tolerance test (0.5 G X min-1 linear ramp to grayout). These tests were conducted before and after 12 consecutive days of exercise-heat acclimation when the subjects exercised on a cycle ergometer at a relative oxygen uptake of 44% to 49% peak oxygen uptake in a hot environment (Ta = 40 degrees C, 42% rh).

Effect of physical training in cool and hot environments on +Gz acceleration tolerance in women.

Rectal temperature (Tre), sweat rate, plasma volume (PV), peak oxygen uptake (peak VO2), and relaxed +Gz acceleration tolerance (0.5 G X min-1 linear to grayout) were measured in 15 healthy women 21-41 years old before and after submaximal isotonic exercise training for 2 h X d-1 on a cycle ergometer. The women had 2 weeks of acceleration runs and Vo2 testing, followed by 8 d of exercise training, post-training acceleration runs on day 9, and peak Vo2 tests on day 10.

Exercise training hypotension: implications for plasma volume, renin, and vasopressin.

To determine the function of changes in plasma volume (PV), plasma renin activity (PRA), and arginine vasopressin (AVP) in the mechanism of the reduction of resting blood pressure during exercise training, resting supine, sitting, and standing systolic (SBP) and 5th-phase diastolic (DBP) blood pressures were measured in 10 men (19-24 yr) before and after an 8-day (2 h/day) training period on a cycle ergometer. The control group (5 men) exercised at 1.4 1/min [44% peak O2 uptake (VO2 max)] at 23.

Deconditioning-induced exercise responses as influenced by heat acclimation.

Five young men were tested on a bicycle ergometer before (Test 1) and after (Test 2) 8 d of heat acclimation (exercise at 50% of Vo2max at 39.8 degrees C DB, 30.0 degrees C WB) and after 8 h of water immersion (Test 3).