Respiratory drives and exercise in menstrual cycles of athletic and nonathletic women

To invesitgate the influence of the midluteal and midfollicular phases of the menstrual cycle on exercise performance and ventilatory drives, we studied six outstanding female athletes, six controls with normal menstrual cycles, and six outstanding athletes who were amenorrheic. In all menstruating subjects resting minute ventilation (VE) and mouth occlusion pressures (P0.1) were higher in the luteal phase (P < 0.0001 and P < 0.02, respectively). Hypoxic (expressed as the hyperbolic shape parameter A) and hypercapnic (expressed as S, ΔVE/ΔPACO₂) ventilatory responses were increased in the luteal phase (P <0.01). The athletes had lower A values during the luteal phase than the nonathletes (P < 0.001). Maximal exercise response, expressed either as total exercise time or maximum O₂ consumption or CO₂ production (VO₂ max or VCO₂ (max) was decreased during the luteal phase but was significantly different at a P <0.05 level only among the nonathletes. Ventilatory equivalent (VE/VO₂) during progressive exercise on a bicycle ergometer was significantly increased during the luteal phase. The amenorrheic athletes showed no changes between the two test periods. The luteal phase of the menstrual cycle induced increases in ventilatory drives and exercise ventilation in both athletes and controls, but the athletes, in contrast to controls, demonstrated no significant decrease in exercise performance in the luteal phase.