Mid Sweden University

We test the hypothesis that breathing oxygen-enriched air (FIO2 = 100%) maintains exercise performance and reduces fatigue during intervals of maximal-intensity cycling. Ten well-trained male cyclists (age 25 +/- 3 years; peak oxygen uptake 64.8 +/- 6.2 ml . kg(-1) . min(-1); mean +/- s) were exposed to either hyperoxic or normoxic air during the 6-min intervals between five 30-s sessions of cycling at maximal intensity. The concentrations of lactate and hydrogen ions [H+], pH, base excess, oxygen partial pressure, and oxygen saturation in the blood were assessed before and after these sprints. The peak (P = 0.62) and mean power outputs (P=0.83) with hyperoxic and normoxic air did not differ. The partial pressure of oxygen was 4.2-fold higher after inhaling hyperoxic air, whereas lactate concentration, pH, [ H+], and base excess (P >= 0.17) were not influenced. Perceived exertion towards the end of the 6-min periods after the fourth and fifth sprints (P < 0.05) was lower with hyperoxia than normoxia (P < 0.05). These findings demonstrate that the peak and mean power outputs of athletes performing intervals of maximal-intensity cycling are not improved by inhalation of oxygen-enriched air during recovery.