What is Amenorrhea?
Amenorrhea is the absence of menstrual cycles for more than 6 months. It is a symptom of impaired hormonal function. Female athletes or women who perform considerable amounts of exercise on a regular basis are at risk of developing 'athletic' amenorrhoea. It was thought for many years that low body fat levels and exercise related chemicals (such as beta endorphins and catecholamines) disrupt the interplay of the sex hormones, estrogen and progesterone. However, recent studies have shown that there are no differences in the body composition, or hormonal levels in amenorrheic athletes. Instead, amenorrhea has been shown to be directly attributable to low energy availability. Many women who exercise at a high level do not take in enough calories to expend on their exercise as well as to maintain their normal menstrual cycles (http://jap.physiology.org/cgi/content/full/84/1/37)
A serious risk factor of amenorrhea is severe bone loss sometimes resulting in osteoporosis and osteopenia. It is the third component of an increasingly common disease known as female athlete triad syndrome. The other two components of this syndrome are osteoporosis and disordered eating. Awareness and intervention can usually prevent this occurrence in most female athletes.