The kinetics of blood rheology during and after prolonged standardized exercise

Abstract

The aim of the study is to define the kinetics of hemorheological changes during and after a standardized bicycle ergometry lasting for 3 hours. Hematocrit, plasma and blood viscosity, red cell aggregation and deformability are measured in 15 volunteers hourly during exercise and followed for 21 hours thereafter. During exercise there is a marked viscidation of the blood which is caused by hemoconcentration and partial loss of red cell deformability. Subsequently blood cell rheology factors normalize. Three hours after exercise there is a marked fall of hematocrit and plasma viscosity. Native blood viscosity declines significantly below baseline values 5 hours after discontinuation of exercise and is still reduced 24 hours after the start of the experiment. The results suggest that the well known exercise-induced hemoconcentration is reversed after discontinuation of exercise when a marked “autohemodilution” takes place.