We hypothesized that progesterone-mediated ventilatory stimulation during the midluteal phase of the menstrual cycle would increase exercise minute ventilation (E; 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 (O_{2 peak}; ml · kg¹ · min¹) 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 O_{2 peak} and Exh test at 70% of their altitude-specific O_{2 peak} 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 E (101 ± 17) and submaximal E (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 O_{2 peak} 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 E is not increased at SL or AA. Moreover, neither maximal nor submaximal exercise performance is affected by menstrual cycle phase at SL or AA.

hypobaric hypoxia; ovarian hormones; submaximal exercise; peak oxygen uptake; ventilatory control

This article has been cited by other articles:

				P. N. Ainslie, A. Barach, K. J. Cummings, C. Murrell, M. Hamlin, and J. Hellemans Cardiorespiratory and cerebrovascular responses to acute poikilocapnic hypoxia following intermittent and continuous exposure to hypoxia in humans J Appl Physiol, May 1, 2007; 102(5): 1953 - 1961. [Abstract] [Full Text] [PDF]

				G. E Foster, D. C McKenzie, and A. W. Sheel Effects of enhanced human chemosensitivity on ventilatory responses to exercise Exp Physiol, January 1, 2006; 91(1): 221 - 228. [Abstract] [Full Text] [PDF]

				G. E. Foster, D. C. McKenzie, W. K. Milsom, and A. W. Sheel Effects of two protocols of intermittent hypoxia on human ventilatory, cardiovascular and cerebral responses to hypoxia J. Physiol., September 1, 2005; 567(2): 689 - 699. [Abstract] [Full Text] [PDF]

				B. St. P. Schneider, J. P. Fine, T. Nadolski, and P. M. Tiidus The Effects of Estradiol and Progesterone on Plantarflexor Muscle Fatigue in Ovariectomized Mice Biol Res Nurs, April 1, 2004; 5(4): 265 - 275. [Abstract] [PDF]

				B. A. Beidleman, S. R. Muza, C. S. Fulco, A. Cymerman, D. T. Ditzler, D. Stulz, J. E. Staab, S. R. Robinson, G. S. Skrinar, S. F. Lewis, et al. Intermittent altitude exposures improve muscular performance at 4,300 m J Appl Physiol, November 1, 2003; 95(5): 1824 - 1832. [Abstract] [Full Text] [PDF]

				T. D. Brutsaert, H. Spielvogel, E. Caceres, M. Araoz, R. T. Chatterton, and V. J. Vitzthum Effect of menstrual cycle phase on exercise performance of high-altitude native women at 3600 m J. Exp. Biol., January 15, 2002; 205(2): 233 - 239. [Abstract] [Full Text] [PDF]

				J. T. Reeves, S. Zamudio, T. E. Dahms, I. Asmus, B. Braun, G. E. Butterfield, R. G. McCullough, S. R. Muza, P. B. Rock, and L. G. Moore Erythropoiesis in women during 11 days at 4,300 m is not affected by menstrual cycle phase J Appl Physiol, December 1, 2001; 91(6): 2579 - 2586. [Abstract] [Full Text] [PDF]

				S. R. Muza, P. B. Rock, C. S. Fulco, S. Zamudio, B. Braun, A. Cymerman, G. E. Butterfield, and L. G. Moore Women at altitude: ventilatory acclimatization at 4,300 m J Appl Physiol, October 1, 2001; 91(4): 1791 - 1799. [Abstract] [Full Text] [PDF]