Brothers, M. D., Hilger, K., Carson, J. M., Sullivan, L., & Byrnes, W. C. (2007). GXT responses in altitude-acclimatized cyclists during sea-level simulation. Medicine and Science in Sports and Exercise, 39, 1727-1735.

This study examined the effects of gender on a graded exercise stress test in moderate-altitude acclimatized cyclists during sea-level simulation. It was hypothesized that alterations in arterial saturation would relate to changes in VO2peak. Competitive cyclists (M = 12; F = 8) who were residents of moderate-altitude locations underwent two tests; one under local normoxic hypobaria, and the other under simulated sea-level conditions.

Under the sea-level condition, there was a significant increase in absolute and relative VO2peak, improved (~4%) economy at lactate threshold, and time-adjusted peak power (7%). There was a considerable variation between Ss (-6% to +25%). Simulated sea-level also resulted in a greater arterial saturation (SaO2) at rest and VO2peak, and significantly less desaturation (4% versus 8%) from rest to VO2peak. The individual variability in VO2peak change was not related to sea-level arterial saturation or any other SaO2 variable analyzed.

Implication. Moderate-altitude residents may attenuate the occurrence of exercise-induced arterial hypoxemia and eliminate the relationship between SaO2 and VO2peak that has been reported among sea-level residents when acutely exposed to altitude. The improvements that occur in predictors of aerobic performance when moderate-altitude residents are exposed acutely to sea-level conditions have a large degree of individual variability.

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