[Pulsatile release of gonadotropins in athletic women]

In athletic women menstrual disorders such as luteal insufficiency, oligomenorrhea and amenorrhea are often seen. It has been suggested that such disorders may be related to hypothalamic-pituitary axis insufficiency caused by physical activity. To investigate the mechanism by which the disorder is promoted, episodic gonadotropin secretion was studied in 10 athletic women (normal ovulatory, 5; short luteal, 5) and 6 non-athletic controls. In the early follicular phase of the menstrual cycle, blood samples were obtained through an indwelling venous catheter at 15-minute intervals for 4 hours. The concentrations of luteinizing hormone (LH) and follicle-stimulating hormones (FSH) were measured by radioimmunoassay. The mean LH and FSH concentrations in the athletic groups were lower than those in the control group. LH pulse frequencies in the short luteal group were 2.8 +/- 0.2 times/four hours (mean +/- standard error) and decreased compared with that of the control group (3.7 +/- 0.2 times/four hours; p less than 0.001). The LH pulse amplitudes of all three groups were similar. Pulsatile FSH secretion was also observed in all the women. Dynamism of FSH was the same as that of LH except for low pulse amplitude in the athletic groups. These data suggest that hypothalamic-pituitary axis insufficiency, especially of hypothalamic origin may be caused by athletic activity.