Effects of hyperoxic training on performance and cardiorespiratory response to exercise.

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.wk(-1), 1 h.d(-1) (10 x 4-min intervals, with 2 min of rest between intervals) at 90% HR(max). 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% VO2max 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. HR(max) did not change for H or N. HR 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.