INFORMATIVE VALUE OF A REBREATHING TEST IN ASSESSING YOUNG MALES' RESISTANCE TO THE COMBINED IMPACT OF HYPOXIA AND HYPERCAPNIA
The study was aimed at revealing the possibilities of applying an isolated space breathing test (rebreathing) in order to ascertain informative integral physiological markers that enable to assess the body resistance to the combined impact of hypoxia and hypercapnia and physical work capacity. For the aim, 63 young male students from the Northeast State University of Magadan aged 18-21 with body mass 69.4 ± 1.2 kg were examined. All examinees were divided into two groups depending upon their response to the rebreathing test that is upon the ratio of oxygen to carbon dioxide collected in the rebreathing bag. Group 1 was made up of low resistance to hypoxia and hypercapnia subjects and group 2 were high resistant ones. Found that, such characteristics as diastolic arterial pressure, heart rate, stroke volume and ratio of oxygen to carbon dioxide after a 3-min rebreathing test can be high informative markers that reflect not only hypoxia and hypercapnia tolerance but the potential rate of physical work capacity. Of note that, no studied hemodynamic or gas exchange indices at rest demonstrated significant changes through the examined groups. The dynamics of the change of very low frequency (VLF) component of the heart rate spectrum power has become the most informative index of the heart rate variability. In group 1 the VLF component proved to reliably decrease at the rebreathing test while group 2 showed its increasing. Subjects from group 1 were less capable to physical work and they experienced more tension during the standard cycling exercise. So, a rebreathing test can be used to estimate the human resistance to the combined impact of hypoxia and hypercapnia and serve as an indirect factor to characterize the rate of physical work capacity.