title: Effects of acute hypoxia on the VO2 max of trained and untrained subjects.
abstract: The purpose of this study was to compare the responses of highly trained (TR) and untrained (UT) subjects' maximal oxygen uptake (VO2 max) while breathing a hypoxic gas mixture. Two groups of healthy volunteers were recruited: (1) trained subjects (n = 8), VO2 max = 67.2 +/- 4.0 ml kg-1 min-1; (2) untrained subjects (n = 8), VO2 max = 45.4 +/- 5.5 ml kg-1 min-1. Both groups were administered maximal cycle ergometer tests under hypoxic (13% O2, 87% N2) and normoxic conditions (21% O2, 79% N2). A pulse oximeter (Ohmeda 3700) was used to estimate arterial haemoglobin saturation (SpO2). The trained group had lower values for SpO2 at maximal exercise (TR = 67.0 +/- 7.1%; UT = 77.5 +/- 9.0%) and greater reductions in VO2 max while breathing the hypoxic gas mixture was linearly correlated with the subjects' normoxic VO2 max (ml kg-1 min-1: r = -0.91). These results indicate that highly trained subjects experience greater percent decrements in SpO2 and VO2 max while breathing a moderately hypoxic gas mixture compared to untrained subjects, and may explain some of the variable decrease observed when VO2 max is measured at simulated altitude.
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville 32610-0154.
authors.forename: D
authors.initials: D
authors.lastname: Martin
authors.forename: J
authors.initials: J
authors.lastname: O'Kroy
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006452:Hemoglobinometry; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D010092:Oximetry; D010100:Oxygen / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance; D010809:Physical Fitness / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology*
chemical_list: D006454:Hemoglobins; D010100:Oxygen