Effect of menstrual cycle phase on exercise performance of high-altitude native women at 3600 m

At sea level normally menstruating women show increased ventilation ((V) over dotE) and hemodynamic changes due to increased progesterone (P) and estrogen (E2) levels during the mid-luteal (L) compared to the mid-follicular (F) phase of the ovarian cycle. Such changes may affect maximal exercise performance. This repeated-measures, randomized study, conducted at 3600 m, tests the hypothesis that a P-mediated increase in (V) over dotE increases maximal oxygen consumption (V)over dot (O2max)) during the L phase relative to the F phase in Bolivian women, either born and raised at high altitude (HA), or resident at HA since early childhood. Subjects (N=30) enrolled in the study were aged 27.7+/-0.7 years (mean+/-S.E.M.) and non-pregnant, non-lactating, relatively sedentary residents of La Paz, Bolivia, who were not using hormonal contraceptives. Mean salivary P levels at the time of the exercise tests were 63.3 pg ml(-1) and 22.9 pg ml(-1) for the L and F phases, respectively. Subset analyses of submaximal (N=23) and maximal (N=13) exercise responses were conducted only with women showing increased P levels from F to L and, in the latter case, with those also achieving true (V) over dot (O2max). Submaximal exercise (V) over dotE and ventilatory equivalents were higher in the L phase (P<0.001). P levels were significantly correlated to the submaximal exercise (V) over dotE (r=0.487, P=0.006). Maximal work output (W) was higher (approximately 5 %) during the L phase (P=0.044), but (V) over dot (O2max) (1min(-1)) was unchanged (P=0.063). Post-hoc analyses revealed no significant relationship between changes in, P levels and changes in (V) over dot (O2max) from F to L (P=0.072). In sum, the menstrual cycle phase has relatively modest effects on ventilation, but no effect on (V) over dot (O2max) of RA native women.