Esposito, F., Limonta, E., Alberti, G., Veicsteinas, A., & Ferretti, G. (2010). Effect of respiratory muscle training on maximum aerobic power in normoxia and hypoxia. Presentation 847 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

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This study assessed the effects of respiratory muscle training, as a means of reducing ventilatory resistance, on VO2max in normoxia and hypoxia. On different days, healthy males (N = 9) performed maximal incremental tests on a cycle ergometer in normoxia and normobaric hypoxia (FIO2 = 0.11), before and after eight weeks of respiratory muscle training (five days per week). During each test, gas exchange variables were measured breath-by-breath.

After respiratory muscle training, no changes in cardiorespiratory and metabolic variables were detected in maximal exercise in normoxia. However, in hypoxia, expired and alveolar ventilation in maximal exercise were significantly higher than in the pre-training condition (gains of 12% and 13% respectively). Accordingly, alveolar O2 partial pressure (PAO2) after respiratory muscle training significantly increased by ~10%. Nevertheless, arterial O2 partial pressure and VO2max did not change when compared to the pre-training condition.

Implication. Respiratory muscle training ameliorated respiratory function but did not have any effect on VO2max under normoxia or hypoxia. In hypoxia, the significant increase in expired and alveolar ventilation at maximum exercise after training led to higher alveolar but not arterial O2 partial pressure values, suggesting an increased A-a gradient. This result, according to the theoretical models of VO2max limitation, seems to contradict the lack of VO2max increase in hypoxia, suggesting a possible role of an increased ventilation-perfusion mismatch.

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