Effects of the Mentrual Cycle on Physiological and Hormonal Responses to Submaximal and Maximal Exercise in Eumenorrheic and Amenorrheic Athletes

The effects of menstrual cycle phase (follicular vs. luteal) and menstrual status (eumenorrhea vs. amenorrhea) on selected physiological (oxygen uptake, minute ventilation, respiratory exchange ratio, heart rate, perceived exertion and time to fatigue), hormonal (adrenocorticotropin, cortisol, prolactin, arginine vasopressin and aldosterone) and other blood (lactate, renin activity and osmolality) parameters were studied following maximal (excluding fluid balance variables) and submaximal (80J V02max for 40 minutes) exercise in eumenorrheic (n=8, 29.0±4.2 yrs) and amenorrheic (n=8, 24.5±5.7 yrs.) runners. Eumenorrheic subjects performed one maximal and one submaximal test during both the follicular (days 2-4) and mid-luteal (6-8 days from onset of luteinizing hormone surge) phases determined via urinary luteinizing hormone and progesterone and plasma estradiol and progesterone assays. The amenorrheic runners performed one maximal and submaximal test. Runners were carefully matched for physical, training and gynecological characteristics. The physiological and plasma lactate responses to the maximal and submaximal exercise were similar in the groups across menstrual phase and status. Among the eumenorrheic runners, all hormones and blood variables were elevated (p< 0.05) 4 minutes post exercise following maximal and submaximal exercise except adrenocorticotropin which was not significantly elevated following the 40 minute run during the follicular phase. Among the amenorrheic runners, pre-exercise cortisol levels were elevated (p< 0.05) and adrenocorticotropin increased after both exercise conditions, however, cortisol was elevated only in response to the submaximal run. The exercise tests did not initiate an increase in prolactin in the amenorrheic runners. Pre-exercise aldosterone was elevated (p < 0.05) and exercise responses were higher during the luteal phase compared to the follicular phase and in the amenorrheic runners. The following conclusions were made: (1) exercise is not limited by menstrual phase or status, (2) hypercortisolism is observed in amenorrheic runners and is apparently characterized by reduced adrenal sensitivity to adrenocorticotropin, (3) amenorrheic runners have an absent prolactin response and this is attributed to ovarian suppression and (4) aldosterone is elevated during the luteal phase and exercise results in a greater aldosterone response during this phase.