Physical Exercise and Menstrual Cycle Alterations

Abstract

The prevalence of menstrual cycle alterations in athletes is considerably higher than in sedentary controls. There appears to be a multicausal aetiology, which makes it extremely difficult to dissociate the effects of physical exercise on the menstrual cycle from the other predisposing factors. From cross-sectional studies it appeared that physical training eventually might lead to shortening of the luteal phase and secondary amenorrhoea. Prospective studies in both trained and previously untrained women have shown that the amount and/or the intensity of exercise has to exceed a certain limit in order to elicit this phenomenon. We hypothesise, therefore, that apart from a certain predisposition, athletes with a training-induced altered menstrual cycle are overreached (short term overtraining, which is reversible in days to weeks after training reduction). Menstrual cycle alterations are most likely caused by subtle changes in the episodic secretion pattern of luteinising hormone (LH) as have been found in sedentary women with hypothalamic amenorrhoea as well as in athletes after very demanding training. The altered LH secretion then, might be caused by an increased corticotrophin-releasing hormone (CRH) secretion which inhibits the gonadotrophin-releasing hormone (GnRH) release. In addition, increased CRH tone will lead to increased beta-endorphin levels which will also inhibit the GnRH signaller. Finally, the continuous activation of the adrenals will result in a higher catecholamine production, which may be converted to catecholestrogens. These compounds are known to be potent inhibitors of GnRH secretion. In conclusion, menstrual cycle alterations are likely to occur after very demanding training, which causes an increase secretion of antireproductive hormones. These hormones can inhibit the normal pulsatile secretion pattern of the gonadotrophins.

The Association of Life Style Factors with Menstrual Symptoms in Women Serving Aboard U.S. Navy Ships

“…In the present study, the only significant association found with exercise was that women with high frequency of exercise were at increased risk of excessive frequency of menstrual periods, which differed from studies that reported excessive exercise was associated with an absence of menstrual periods [6,13,18,19]. Exercise interventions have been associated with a beneficial effect on dysmenorrhea [13][14][15][16], and more frequent exercise has been associated with less severe symptoms [17].…”

“…al. [12] reported that there were no significant differences between women with and without dysmenorrhea in exercise behavior, and other studies have associated excessive exercise with delayed menarche, lack of ovulation and the absence of menstrual periods [6,13,18,19].…”

Knee joint kinaesthesia and neuromuscular coordination during three phases of the menstrual cycle in moderately active women

“…These are new findings that may be of importance for the previously reported increased risk of injuries during the premenstrual phase of the menstrual cycle and during the first days of menses [4,11]. The ideal menstrual cycle is 28 days long with ovulation at cycle day 14, but the range of a normal cycle length is between 22 days and 36 days [18]. Furthermore, anovulatory cycles may occur despite regular periods and thus, affecting hormonal levels.…”

Growth hormone responses to continuous and intermittent exercise in females under oral contraceptive therapy

“…Testing during the OCNU phase occurred on days 3±5 of the menstrual cycle when the subjects abstained from OCU in the normal course of therapy. In normally menstruating females not under OC therapy, this is a period of low endogenous estrogen levels, as levels gradually peak towards mid-cycle (Keizer and Rogol 1990). Although full metabolic clearance of exogenous estrogen from the circulation after the last day of OC ingestion of the previous menstrual cycle was unlikely, signi®cant levels of it were expected to have cleared (Bonen et al 1991).…”