Plasma and red cell volume after prolonged severe exercise

Abstract

On six subjects plasma volume (Evans blue space) was determined before and 1 hr after an 85-km race in cross-country skiing. The total water loss during the 5- to 9.5-hr competition was estimated to be 5.9 liters, and at the time of measuring the reduction in body weight was 3.9 kg or 5.5% of the weight. The plasma volume was increased 0.41 or 11% (0.01 > P > 0.001). A similar study was undertaken with measurements of red cell volume (Cr⁵¹) on five subjects. The decrease in red cell volume was 0.081 or 3.2%. These findings are discussed in light of the small reduction in aerobic work capacity in combination with a marked decrease in total work output after the race. In five workers in a steel mill (three at a hot bank and two at a smelting furnace) the total water loss during an 8-hr shift in a hot environment was 3.9 liters and the reduction in body weight was 1.1 kg or 1.9% of the weight. The blood volume (I¹³¹) was increased by 0.23 liters or 3.5%. dehydration; blood volume Submitted on October 16, 1963