Previous studies have indicated that aerobic pathways contribute to 13-27% of the energy consumed during short-term (10-20-second) sprinting exercise. Accordingly, the present investigation was designed to test the hypothesis that prior breathing of oxygen-enriched air (FinO2=60%) would enhance power output and reduce fatigue during subsequent sprint cycling. Ten well-trained male cyclists (mean ± SD, age: 25±3 years, height: 186.1±6.9 cm, body mass: 79.1±8.2 kg, maximal oxygen uptake [VO2max]: 63.2±5.2 ml·kg-1·min-1) took 25 breaths of either hyperoxic (HE) or normoxic (NO) air before performing 15 sec of cycling at maximal exertion. During this performance, the maximal and mean power outputs were recorded. The concentration of lactate, pH, partial pressure of and saturation by oxygen, [H+] and base excess in arterial blood were assessed before and after the sprint. The maximal (1053±141 W for HE versus 1052±165 W for NO; P = 0.77) and mean power outputs (873±123 versus 876±147 W; P = 0.68) did not differ between the two conditions. The partial pressure of oxygen was approximately 2.3-fold higher after inhaling HE in comparison to NO, while lactate concentration, pH, [H+] and base excess (best P = 0.32) after sprinting were not influenced by exposure to HE. These findings suggest that the peak and mean power outputs of athletes performing short-term intense exercise cannot be improved by pre-exposure to oxygen-enriched air.