Physical exercise-induced changes and season-associated differences in the pituitary-ovarian function of runners and joggers.

The hormonal responses to energetic chronic exercise and to seasonal shift from autumn to spring were evaluated by measuring concentrations of serum FSH, LH, PRL, estradiol (E2), progesterone (P), testosterone (T), and sex hormone-binding globuline (SHBG) during 1 menstrual cycle in the autumn (light training season) and 1 in the spring (hard training season) in 18 endurance runners and 12 age-matched nonrunning women, and in 13 joggers and 11 age-matched nonjogging women. The appearance, growth, and maximal size of the ovarian follicles were monitored by ultrasonography. The high intensity training of the runners was associated with decreased concentrations of FSH on cycle days 7-8 in the autumn, E2 on cycle days 12-13 in the spring and days 22-23 in both seasons, P on cycle days 20-21 in both seasons and days 22-23 in the autumn, and T on cycle days 12-13, 14-15, and 22-23 in the spring. Jogging, however, did not alter the concentrations of these hormones. Using as criteria the presence of 2 or 3 abnormal values of the 3 indicators used for evaluation of folliculogenesis (midfollicular E2 lower than 0.09 nmol/liter, luteal phase P lower than 7 nmol/liter, and peak diameter of the largest ovarian follicle less than 15 mm), seriously disturbed folliculogenesis was found in 50% of the 32 study cycles of the runners and 9% of the 23 cycles of their controls (P less than 0.01). In all four study groups, there was a significant seasonal difference in the concentrations of ovarian hormones, with lowered E2, P, and T levels in the autumn. There were no differences in the serum concentrations of SHBG between the study groups or between the autumn and the spring. High training activity and a dark photoperiod appeared to independently suppress ovarian activity and were not associated with chronic changes in anterior pituitary hormone or SHBG concentrations.