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 \( {\left( {\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{{2\max }} } \right)} \) and maximal power (Pmax) in subjects exhibiting exercise-induced arterial hypoxemia (EIH) at sea level. Sixteen competing male cyclists \( \ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{{2\max }} \)>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 (Δ 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). \( \ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{{2\max }} \) 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 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 \( \ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{{2\max }} \) and power for especially EIH subjects.