Babcock, C. J., & Kirby, T. E. (2008). The effect of intermittent simulated altitude exposure via re-breathing on cycling performance. ACSM 55th Annual Meeting Indianapolis. Presentation number, 733.

This study examined the effects of intermittent simulated altitude exposure via re-breathing on cycling performance. Well-trained male cyclists (N = 18) used a re-breathing device for 15 days. Ss were randomly assigned to either a low constant exposure group (control) in which oxygen saturation was held constant (98%); or progressively increased exposure group, where oxygen saturation was progressively reduced (90% to 77% over 15 days). An exercise performance test was performed to familiarize Ss to the protocol, prior to simulated altitude exposure, and following simulated altitude exposure. The critical power protocol was used to examine power output in varied time trial efforts. Performance was also investigated through measurements of lactate, oxygen consumption, and heart rate.

There was significant improvement for the progressively increased exposure group after the experience in the 15- and 60-minute time-trial efforts compared to no improvement in the control group. The progressively increased exposure group improvement was 3-4.5% in average power output. There were no significant differences in the power outputs of the 3-minute time trial for either group after the experiment. There were no significant differences in hematological measures after the experiment for either group.

Implication. In competitive cyclists, the use of a re-breathing device resulted in improved performance for events that rely heavily on aerobic power but not for anaerobic power. "These findings are similar in regard to performance adaptations found in other acclimatization investigations, terrestrial or simulated. It is suggested that the re-breathing form of simulated altitude may be utilized as an alternative to terrestrial or other forms of simulated altitude, in efforts to mediate performance gains in endurance type events".

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