EFFECTS OF MENSTRUAL-CYCLE PHASE ON ATHLETIC PERFORMANCE

The purpose of this study was to examine the effects of menstrual cycl e phase on four selected indices of athletic performance: aerobic capa city, anaerobic capacity, isokinetic strength, and high intensity endu rance. Sixteen eumenorrheic women (VO2max greater than or equal to 50 ml . kg(-1). min(-1)) were tested during the early follicular (F) and midluteal (L) phases of the menstrual cycle. Cycle phases were confirm ed by serum estradiol and progesterone assays. No significant differen ces were observed between F and L tests in weight, percent body fat, s um of skinfolds, hemoglobin concentration, hematocrit, maximum heart r ate, maximum minute ventilation, maximum respiratory exchange ratio, a naerobic performance, endurance rime to fatigue (at 90% of VO2max) or isokinetic strength of knee flexion and extension. Both absolute and r elative VO2max, however, were slightly loer in L than in F (F = 3.19 /- 0.009 . min(-1), L 3.13 +/- 0.08 . min(-1), P = 0.04; and F = 53.7 +/- 0.9 ml . kg(-1). min(-1), L = 52.8 +/- 0.8 ml . kg(-1). min(-1), P = 0.06). These results suggest that the cyclic increases in endogenou s female steroid hormones of an ovulatory menstrual cycle may have a s light, deleterious influence on aerobic capacity, with potential impli cations for individual athletes. Nevertheless, the cycle phase did not impact significantly on the majority of the other performance tests a nd cardiorespiratory variables measured in this study.