Abstract

The effects of two one-hour exercise bouts on a cycle ergometer were investigated during mid-menstrual cycle at 60% (low intensity exercise, LI) and 85% (high intensity exercise, HI) of peak oxygen consumption (VO2peak) on serum concentrations of oestradiol (E-2), follicle stimulating hormone (FSH), luteinising hormone (LH), and progesterone (P) in 5 eumenorrheic women. Venous blood samples were collected at rest, 40 and 60 min of exercise, and at 20 min of recovery during the exercise trials, as well as before and after 1 h of rest during the control trial. The concentrations of E-2, P, LH, and FSH were determined in serum by fluoroimmunoassay and corrected for changes in plasma volume. Analysis of covariance, using resting values as the covariate, showed that mean LH (+/-SE) decreased from rest to 60 min of exercise (9.76+/-4.8 6 to 7.31+/-3.52 mIU/ml; P<0.05) in LI and from rest to 40 and 60 min of exercise and 20 min of recovery in HI (7.7+/-3.96, 6.04+/-2.73, 5.48+/-3.00, 5.68+/-2.24 mIU/ml, respectively; P<0.05). E-2 increased significantly at both intensities (87.1+/-32.7 to 108.1+/-46.7 pg/ml in LI and from 98.7+/-45.1 to 143.9+/-56.6 in HI; P<0.05). P increased significantly only at 60 min in HI (2.55+/-2.03 to 2.87+/-2.11 ng/ml; P<0.05). The results suggest that a single bout of a prolonged, intense exercise significantly affects pituitary and ovarian hormones that control the menstrual cycle more than low-intensity exercise. Verf.-Referat