Journal of Applied Physiology, Vol 41, Issue 6 815-821, Copyright © 1976 by American Physiological Society
Aerobic power as a factor in women's response to work in hot environments
B. L. Drinkwater, J. E. Denton, I. C. Kupprat, T. S. Talag and S. M. Horvath
Twelve young women, athletes (n = 6) and nonathletes (n = 6), walked on a
treadmill at loads equivalent to approximately 30% Vo2 max for two 50-min
periods in three environments: 1) 28 degrees C, 45% rh, 2) 35 degrees C,
65% rh, and 3) 48 degrees C, 10% rh. There were no differences between
groups in rectal temperature, heart rate, evaporative heat loss, or mean
skin temperature at 28 or 35 degrees C or during the first work period in
the 48 degrees C environment. However, a significantly lower cardiac output
(Q) and stroke volume (SV) observed for nonathletes by the 46th min of work
at 48 degrees C may explain why no nonathletes were able to complete a 2nd
h of work while four of six athletes successfully finished the period. It
appears that in conditions of severe heat stress (48 degrees C) athletes
were able to maintain a cardiac output sufficient to meet the metabolic
requirements and the large increase in peripheral blood flow for a longer
period of time than nonathletes.
