Hematological Aspects of Heat Stress in Trained and Untrained Men with Special Emphasis on Erythrocyte Volume, Acid-Base Balance and Fluid-Electrolyte Shifts.
Final rept. 1 May 76-31 Aug 78,
SAINT LOUIS UNIV MO DEPT OF PHYSIOLOGY
Pagination or Media Count:
The results of the present study indicate that with 30 min. of continued sub-maximal exercise in a cool 24 C or warm environment 40 C the rates of plasma volume decrease and restoration are virtually identical. At all levels of sub-maximal performance restoration of plasma volume was 80-90 complete 30 min. post-exercise and 100 complete in 60 minutes. The regression equations for calculating proportional changes in plasma volume, using changes in hematocrit and hemoglobin, indicate that the changes in mean erythrocyte volume MCV were small. However, based on statistical analyses, it is apparent that significant changes in MCV dc occur during sub-maximal exercise. Physical training decreased plasma osmolarity and increased the size of the human erythrocyte. Proportionally, the shift of plasma water during maximal exercise was similar before and after training. Acclimatization to heat induced increments in MCV which, however, were not statistically significant. In heat acclimatized subjects there was a tendency for quicker restoration of plasma volume than in non-heat acclimatized subjects after exercise in the heat. These changes are discussed with reference to concomittant changes in plasma osmolarity and plasma protein.
- Stress Physiology