Exercise V̇E and physical performance at altitude are not affected by menstrual cycle phase

We hypothesized that progesterone-mediated ventilatory stimulation during the midluteal phase of the menstrual cycle would increase exercise minute ventilation (V̇E l/min) at sea level (SL) and with acute altitude (AA) exposure but would only increase arterial O₂ saturation (Sa(O₂), %) with AA exposure. We further hypothesized that an increased exercise Sa(O₂) with AA exposure would enhance O₂ transport and improve both peak O₂ uptake (V̇O(2peak); ml·kg^-1·min^-1) and submaximal exercise time to exhaustion (Exh; min) in the midluteal phase. Eight female lowlanders [33 ± 3 (mean ± SD) yr, 58 ± 6 kg] completed a V̇O(2 peak) and Exh test at 70% of their altitude-specific V̇O(2peak) at SL and with AA exposure to 4,300 m in a hypobaric chamber (446 mmHg) in their early follicular and midluteal phases. Progesterone levels increased (P < 0.05) ~20-fold from the early follicular to midluteal phase at SL and AA. Peak V̇E (101 ± 17) and submaximal V̇E (55 ± 9) were not affected by cycle phase or altitude. Submaximal Sa(O₂) did not differ between cycle phases at SL, but it was 3% higher during the midluteal phase with AA exposure. Neither V̇O(2peak) nor Exh time was affected by cycle phase at SL or AA. We conclude that, despite significantly increased progesterone levels in the midluteal phase, exercise V̇E is not increased at SL or AA. Moreover, neither maximal nor submaximal exercise performance is affected by menstrual cycle phase at SL or AA.