Few oligo-amenorrheic athletes have vasomotor symptoms

Abstract

Objective: To assess whether women with athletic oligo-amenorrhea have vasomotor symptoms. Material and methods: A mailed questionnaire was sent to 252 female athletes about vasomotor symptoms. Identical questions were also mailed to 1523 peri- and postmenopausal women. Results: The prevalence of vasomotor symptoms was low in female athletes with oligo- and amenorrhea and similar to that found in athletes with regular menstruations. The prevalence was significantly lower than in menopausal women. Although more than a third of the menopausal women had hormone replacement therapy, 30% of them still had vasomotor symptoms at least every week compared with only 2% of the oligo-amenorrheic athletes. Conclusion: Vasomotor symptoms are very uncommon in oligo-amenorrheic athletes, although many of them are hypoestrogenic. It was suggested that one factor contributing to these symptoms around menopause is low hypothalamic activity of β-endorphins, which makes the thermoregulatory centre labile. On the other hand, supraphysiological activity in hypothalamic β-endorphins may cause the oligo-amenorrhea in athletes, but may stabilise the thermoregulatory centre and thus prevent hot flushes.

Introduction

The majority of women in Western countries report vasomotor symptoms with hot flushes and sweating around menopause [1], [2]. Vasomotor symptoms are the most typical symptoms around menopause [1]. During the flushes it is possible to objectively register increased pulse rate, skin-temperature, skin-moisture, peripheral vasodilatation and decreased central temperature using plethysmography, thermogram or registration of skin-conductance [3]. There is a temporal correlation between elevations of serum luteinizing hormone (LH) and the flushes [4], [5]. The flushes are probably elicited by a sudden resetting in the thermoregulatory center, whereas the rapid elevations of LH are caused by an increase in gonadotrophin releasing hormone (GnRH) pulse rate or amplitude [4], [5].

β-Endorphins are regulatory peptides secreted by neurones in the hypothalamus, and are in turn regulated by sex steroids. β-Endorphins inhibit the release of GnRH and, if β-endorphin concentrations are lower after menopause, the secretion of GnRH, and thereby also LH, is allowed to increase [6], [7]. A decrease in β-endorphin levels after menopause probably also affects the thermoregulatory centre, located in the hypothalamus, and makes it less stable. This postulated mechanism concerning menopausal vasomotor symptoms is speculative, but β-endorphins are known to influence the thermoregulation in animal models [8], [9] as well as in humans [10].

Already in 1962 Erdelyi reported on menstrual disorders in female athletes [11]. Since then an increasing number of reports have shown that menstrual disorders including amenorrhea are common in women taking part in strenuous exercise [12], [13], [14], [15]. Decreased bone density and fracture risk are signs of the hypoestrogenism, which is the cause of the amenorrhea in these subjects [15].

Vasomotor symptoms, typical and characteristic symptoms in hypoestrogenic postmenopausal women, have not been reported in amenorrheic athletic women, although they are known to have low estrogen levels. The reason could be that they do not experience such symptoms, but also that these symptoms have not been of interest to researchers. If vasomotor symptoms do not exist among amenorrheic athletes this could be a clue to the aetiology of both the menstrual disturbance in athletes and the vasomotor symptoms around menopause.

The aim of the present study was to assess if oligo- and amenorrheic athletes have vasomotor symptoms and in such case to compare the prevalence of flushes with that found in women around menopause.