Journal of Applied Physiology, Vol 39, Issue 4 643-647, Copyright © 1975 by American Physiological Society
Untrained females: effects of submaximal exercise and heat on body fluids
L. C. Senay Jr and S. Fortney
Five untrained females having no history of heat exposure worked in a cool
(16-20 degrees C db, 28% rh) environment on day 1 and a warm environment on
day 2 (45 degrees C db, 28% rh). Exercise level (bicycle ergometer) was 30%
of individual Vo2 max values and work time on both days was 45 min. Venous
blood samples were obtained at rest, after 40 min of exercise and 25 min
after exercise ceased. Analysis of blood samples indicated an 8.3% increase
in Hct during exercise on day 1 and a plasma volume reduction of 12.8%
though total circulating protein increased 11.5%. Except for K+ all
parameters approximated control values within 25 min postexercise. On day
2, exercise in heat caused a 12% increase in Hct and a plasma volume
reduction of 17.7%. Mean total protein did not significantly change from
resting values. These data indicated that for a given % Vo2 max, untrained
females suffer considerably greater reductions in plasma volumes than do
exercised males. Similar to males, dilatation of the cutaneous vascular bed
in unacclimatized females resulted in loss of protein from the vascular
volume.
