Effect of hyperoxia on maximal O2 uptake in exercise-induced arterial hypoxaemic subjects

This study focuses on the effect of hyperoxia on maximal oxygen uptake VO2max and maximal power (Pmax) in subjects exhibiting exercise-induced arterial hypoxemia (EIH) at sea level. Sixteen competing male cyclists VO2max > 60 ml.min(-1).kg(-1)) performed exhaustive ramp exercise (cycle-ergometer) under normoxia and moderate hyperoxia (FIO2 = 30%). After the normoxic trial, the subjects were divided into those demonstrating EIH during exercise [arterial O2 desaturation (delta SaO2) >5%; n = 9] and those who did not (n = 7). Under hyperoxia, SaO2 raised and the increase was greater for the EIH than for the non-EIH group (P<0.001). VO2max improved for both groups and to a greater extent for EIH (12.8 +/- 5.7% vs. 4.2 +/- 4.6%, P<0.01; mean+/-SD) and the increase was correlated to the gain in SaO2 for all subjects (r = 0.71, P<0.01). Pmax improved by 3.3 +/- 3.3% (P<0.01) regardless of the group. These data suggest that pulmonary gas exchange contributes to a limitation in VO2max and power for especially EIH subjects.