The Causes of Delayed Menarche in Female Athletes

- THE CAUSES OF DELAYED MENARCHE IN FEMALE ATHLETES -

INTRODUCTION

Greater emphases on the benefits of exercise have led to a greater participation of women in sport at all levels. Exercise has been promoted, endorsed and encouraged in the medical community as a way to reduce stress and maintain a healthy lifestyle. While moderate exercise does provide valuable benefits, intensive exercise associated with elite female athletes poses serious health risks to the female body.

The female reproductive system is very intricate and highly sensitive to physiological stress. This increased stress level is often associated with several reproductive abnormalities such as delayed menarche, primary and secondary amenorrhea and oligomenorrhea occurring in 6-79% of women engaged in athletic activity (Warren and Perlroth 2001). This wide range of percentages is a result of various levels of athletic discipline and level of competition (Abraham et al. 1982, Glass et al. 1987).

The aforementioned reproductive abnormalities are largely the result of hypothalamic dysfunction and disturbance of the gonadotropin-releasing hormone (GnRH) pulse generator. This suppression of GnRH results in possible infertility and an irreversible decrease in bone density. The scientific community seems to be split however, on the specific trigger that causes the reproductive dysfunction in athletes. There are two theories, which are widely accepted, the body composition theory and the energy drain theory.

The body composition theory states that intensive athletic training activates the hypothalamic-pituitary-adrenal axis, which disrupts GnRH pulsatility and hence menstrual function. It is theorized that this suppression of the menstrual cycle may be a physiological adaptation to low caloric intake (Warren 1980). There is much evidence that suggests that the hormone leptin may help regulate reproductive function. Leptin levels have been found to change with respect to fat stores and energy availability. So, it can be reasoned that a low caloric intake will result in low levels of leptin. A study of females showed that had there is a certain threshold level of leptin that when gone below will result in no menstrual cycle (Kopp et al. 1997). Leptin receptors have also been located on hypothalamic control of the GnRH pulse generator thus leptin may be a critical factor involved in signaling low energy