Journal of Applied Physiology, Vol 43, Issue 2 308-311, Copyright © 1977 by American Physiological Society
Recurrent heat exposure: enzymatic responses in resting and exercising men
R. P. Francesconi, J. T. Maher, G. D. Bynum and J. W. Mason
Heat acclimatization was induced in a group of healthy male test subjects
by repetitive treadmill walking (5.6 km-h-1, 49 degrees/27 degrees C
dry/wet bulb, 90 min-day-1, 7 days). A second group of men, paired for
maximal O2 consumption and body weight, remained sedentary under identical
environmental conditions. Total plasma protein increased significantly
after 45 (P less than 0.05) and 90 (P less than 0.025) min of exercise on
the first day of heat exposure, yet after 7 days no increments occurred.
Even after heat acclimatization was achieved (day 7), plasma levels of
creatine phosphokinase increased during the 90-min walk in the heat (time O
vs. 90, P less than 0.025), as was also the case on day 1 (P less than
0.05). Levels of lactate dehydrogenase, glutamate-oxaloacetate
transaminase, and glutamate-pyruvate transaminase were not significantly
affected by exercise in the heat either before or after heat
acclimatization. No correlations could be drawn between base-line enzyme
levels and state of physical conditioning.
