[The regulation of breathing during the inhalation of different densities of gas mixtures under increasing muscle work in man].

The maximal working ability of the subjects did not depend on the composition of inhaled gas mixtures. The lung ventilation, oxygen consumption and CO2 release, as well as the heart rate were increasing along with the physical load increase, the changes being not dependent on the mixture composition. A significant decrease in the effort of the respiratory muscles, in the respiration work and in central inspiratory activity occurred in inhalation of a helium-oxygen mixture, whereas these parameters increased in breathing with an argon-oxygen mixture. The compensatory responses of the respiratory system seem to appear on the basis of afferents from the lungs and respiratory muscles mechanoreceptors as well as on account of the segmentary level reflexes and the properties of a muscular fibre itself.