the,~nstrual Cycle

In the work described in this theses, hormonal '.and physio-logical responses to exercise were investigated in women in relation to the menstrual cycle. Alterations in estradiol, progesterone, luteinizing or follicle stimulating hormones with exercise may interfere with the delicate hormonal balance which is necessary for regular ovulatory menstrual cycles. At rest, estradiol and progesterone have effects on carbohydrate and lipid metabolism, on pulmo~ary and cardiovascular function and on the plasma concentrations of a number of other hormones, all of which may also be important during exercise. As wide.fluctuations in resting levels of the ovarian steroids occur during a normal menstrual cycle, they may influence exercise performance or the physiological adaptations to exercise at different times in the cycle. To investigate these.issues, nine subjects were studied during cycle ergometer exercise at three exercise intensities on two occasions in the menstrual cycle. Tests were conducted when resting levels of estradiol and progesterone were low, in the early follicular phase, and when the concentrations of both hormones were elevated. in the mid-luteal phase. Separation into the two phases was confirmed by hormone analysis. For the first time. it has been shown that in women. exercise is associated with an increase in the plasma levels of estradiol. progesterone. luteinizing hormone and follicle stimulating hormone. iii "The response of the ovarian hormones,is more marked in the luteal., Ii ' phase while the gonadotropins are affected only in the follicula