In humans and higher animals, a trade-off between sufficiently high erythrocyte concentrations to bind oxygen and sufficiently low blood viscosity to allow rapid blood flow has been achieved during evolution. Optimal hematocrit theory has been successful in predicting hematocrit (HCT) values of about 0.3-0.5, in very good agreement with the normal values observed for humans and many animal species. However, according to those calculations, the optimal value should be independent of the mechanical load of the body. This is in contradiction to the exertional increase in HCT observed in some animals called natural blood dopers and to the illegal practice of blood boosting in high-performance sports. Here, we present a novel calculation to predict the optimal HCT value under the constraint of constant cardiac power and compare it to the optimal value obtained for constant driving pressure. We show that the optimal HCT under constant power ranges from 0.5 to 0.7, in agreement with observed values in natural blood dopers at exertion. We use this result to explain the tendency to better exertional performance at an increased HCT.

Department of Anaesthesiology and Intensive Care St Anne's University Hospital and International Clinical Research Center Pekarska 53 656 91 Brno Czech Republic

Department of Bioinformatics Matthias Schleiden Institute Friedrich Schiller University Jena Ernst Abbe Platz 2 07743 Jena Germany

Institute of Zoology and Evolutionary Research Friedrich Schiller University Jena Erbertstrasse 1 07743 Jena Germany

Citace poskytuje Crossref.org