To assess the effects of respiratory muscle training (RMT) on maximum oxygen uptake (over(V, ̇) O2 max) in normoxia and hypoxia, 9 healthy males (age 24 ± 4 years; stature 1.75 ± 0.08 m; body mass 72 ± 9 kg; mean ± SD) performed on different days maximal incremental tests on a cycle ergometer in normoxia and normobaric hypoxia (F I O2 = 0.11), before and after 8 weeks of RMT (5 days/week). During each test, gas exchange variables were measured breath-by-breath by a metabolimeter. After RMT, no changes in cardiorespiratory and metabolic variables were detected at maximal exercise in normoxia. On the contrary, in hypoxia expired and alveolar ventilation (over(V, ̇) E and over(V, ̇) A, respectively) at maximal exercise were significantly higher than pre-training condition (+12 and +13%, respectively; P <0.05). Accordingly, alveolar O 2 partial pressure (P A O2) after RMT significantly increased by ∼10%. Nevertheless, arterial P O2 and over(V, ̇) O2 max did not change with respect to pre-training condition. In conclusion, RMT improved respiratory function but did not have any effect on over(V, ̇) O2 max, neither under normoxic nor hypoxic condition. In hypoxia, the significant increase in over(V, ̇) E and over(V, ̇) A at maximum exercise after training lead to higher alveolar but not arterial P O2 values, revealing an increased A-a gradient. This result, according to the theoretical models of over(V, ̇) O2 max limitation, seems to contradict the lack of over(V, ̇) O2 max increase in hypoxia, suggesting a possible role of increased ventilation-perfusion mismatch.
- Aerobic exercise
- over(V, ̇)
- Oxygen uptake
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine