In addition, comparing different sports, the long distance runners had the lowest level of estradiol and progesterone. Although the mechanism of EAMD-induced damages of ovarian ultrastructure remains unclear, studies suggested that reduction of ovarian hormones by exercise may be associated with the hypothalamic GnRH,which is known as an energy metabolism factor. The reduction of GnRH release indirectly decreases the secretion of estradiol and progesterone.