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

Abstract

To investigate the influence of the midluteal and midfollicular phases of the menstrual cycle on exercise performance and ventilatory drives, female athletes, 6 controls with normal menstrual cycles and 6 outstanding athletes who were amenorrheic were studied. In all menstruating subjects resting minute ventilation (.ovrhdot.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 parameter A) and hypercapnic (expressed as S, .DELTA..ovrhdot.VE/.DELTA.PACO2 [ventilation change-arterial CO2 pressure change ratio]) 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 as total exercise time or maximum O2 consumption or CO2 production (.ovrhdot.VO2 max or .ovrhdot.VCO2 max) was decreased during the luteal phase but was significantly different at a P < 0.05 level only among the nonathletes. Ventilatory equivalent (.ovrhdot.VE/.ovrhdot.VO2) during progressive exercise on a bicycle ergometer was significantly increased during the luteal phase. Amenorrheic athletes showed no changes between the 2 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.