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 O-2 desaturation ( Delta SaO(2)) > 5%; n= 9] and those who did not ( n= 7). Under hyperoxia, SaO(2) raised and the increase was greater for the EIH than for the non-EIH group ( P < 0.001). VO(2)max 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 SaO(2) 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 VO(2)max and power for especially EIH subjects.