[Effect of physical training on the manifestation of reactions to breathing a gas mixture containing 5% CO2 and 14% O2].

The effect of a hypoxic-hypercapnic gas mixture (5% CO2 + 14% O2) on the exercising man was studied. At a low work load inhalation of this gas mixture inhibited gas exchange, and after 10 month training stimulated it. Thus, increase in physical endurance was followed by increase in human resistance to O2 deficiency and CO2 excess in the breathing mixture.