Purpose: To determine whether training in a hyperoxic environment would result in greater increases in VO2max and performance at 90% VO2max as compared with training in normoxia. Methods: In a single blind design nine athletes trained for 6 wk on a cycle ergometer 3 d[middle dot]wk-1, 1 h[middle dot]d-1 (10 x 4-min intervals, with 2 min of rest between intervals) at 90% HRmax. Training HR range was maintained by adjusting the power output. Subjects were randomly assigned to H (60% O2) or N (21% O2) breathing conditions for training. After 12 wk of detraining, a second 6-wk training protocol was completed with the breathing conditions reversed. VO2max, performance time at 90% VO2max and cardiorespiratory response to a steady-state exercise at 80% [latin capital V with dot above]O2max were measured pre- and posttraining. All pre- and posttraining tests were conducted under normoxic conditions. Results: There were no significant differences between pretraining results for any of the parameters. Power output was 8.1% higher while training in H compared with N, to maintain training HR. Both H and N training resulted in increased performance time, with H being greater than N. Although there was a trend for a greater increase in VO2max after H versus N training, this difference was not significant. HRmax did not change for H or N. HR and VE at 80% VO2max decreased posttraining with no differences between H and N. Conclusion: The data showed that a higher power output was required to maintain HR during H training. This increased training intensity during H resulted in improved exercise performance whereas cycling at 90% VO2max in room air and may be due to peripheral factors because cardiorespiratory responses were similar.
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