Comment on Health Issues for Women Athletes: Exercise-Induced Amenorrhea

Carl De Crée

Reproductive Endocrinology and Sports Medicine Department of Applied and Experimental Reproductive Endocrinology Institute for Gyneco-Endocrinological Research B-3000 Leuven 3, Belgium

Since the 1970s, the problem of exercise-induced menstrual irregularities and its possible consequences (osteoporosis, subfertility) has been recognized and studied in detail. Warren et al. (1) present a chrestomathy of theirs and a number of other North American authors who have delivered important contributions to our understanding of the etiology and reproductive health of female athletes. It is suggested that secondary amenorrhea, inadequate luteal phase, and the female athlete triad are a caused by a disturbance of normal GnRH pulsatility, which is provoked by weight loss or dietary restriction. Indeed, studies of Loucks et al. (2) have clearly pointed out how a disturbance of a critical energy balance, possibly accompanied by low T3 levels, may lead to menstrual problems.

However, we feel that the clear focus of North American authors on this specific mechanism seems to have led to a generalized belief that this is the sole mechanism involved or, in other words, that all or most exercise-induced menstrual problems result from a poor energy balance.

Nevertheless, Keizer et al. (3) have clearly shown that exercise-intensity on its own can produce the same menstrual problems in eucaloric athletes. Subsequent investigations by ourselves (4), Russel et al. (5), and Snow et al. (6) have demonstrated that regular high-intensity exercise leads to a shift in estrogen metabolism from 16{alpha}- to C-2 oxidation and formation of the so-called catecholestrogens. The intrahypothalamic interactions between increased catecholestrogen formation and norepinephrine exerts important effects on the GnRH oscillator, which can produce menstrual problems. This mechanism may be activated without any interference from an individual’s energy balance, and it is even speculated that changes in eating behavior might even be secondary to such steroid-mediated intrahypothalamic and metabolic effects.

Finally, it is opportune to mention that there are several subtle, but numerous differences between menstrual problems that seem to find their origin in eating behavior and those purely resulting from exercise. Such differences are reflected in a specific hormonal profile (differences in T3, IGFBP-1, 17,20-desmolase, among others), but it has also been speculated that disturbed eating behavior form of menstrual problems in athletes might be genetically predisposed and associated with the so-called 5-HT2A receptor (-1438 AA) promoter polymorphism.

The laboratory techniques required for the analysis of some of these mechanism are complicated and laborious, but it does not justify that our attention is reduced to the impact of diet. Only a comprehensive approach linking diet, hormone metabolism, and genetics will lead to a full understanding of the etiology of exercise-induced menstrual problems.

References

  1. Warren MP, et al. 1999 Health issues for women athletes: exercise-induced amenorrhea. J Clin Endocrinol. 84:1892–1896.
  2. Loucks AB, Verdun M, Heath EM. 1998 Low energy availability, not stress of exercise, alters LH pulsatility in exercising women. J Appl Physiol. 84:37–46.
  3. Keizer HA, Platen P, Menheere, et al. 1989 The hypothalamic/pituitary axis under exercise stress: the effects of aerobic and anaerobic training. In: Rogol A, Laron Z, eds. Hormones and Sport. Serono Symposium Publications, Vol 55. New York: Raven Press; 101–105.
  4. De Crée C, Ball P, Seidlitz B, et al. 1997 Responses of catecholestrogen metabolism to acute graded exercise in normal menstruating women before and after training. J Clin Endocrinol Metab. 82:3342–3348.
  5. Russel JB, Mitchell DE, Musey PL. 1984 The role of ß-endorphin and catechol estrogens on the hypothalamic-pituitary axis in female athletes. Fertil Steril. 42:690–695.
  6. Snow RC, Barbieri RL, Frisch RE. 1989 Estrogen 2-hydroxylase oxidation and menstrual function among elite oarswomen. J Clin Endocrinol Metab. 69:369–376.




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