Athletic Amenorrhea: Women at Risk

Editor’s Note: This post was originally published March 2014 and has recently been updated and revised for accuracy and comprehensiveness.

It is estimated that up to 45 percent of female athletes in certain sports experience menstrual irregularity, also referred to as Athletic Amenorrhea. Within the last 20 years, our society has witnessed a significant increase in the level of athletic participation by women and as a result, women are more aware of the changes experienced in their menstrual cycle.

There is highly regarded speculation that in some way the female body “senses’ when energy reserves are inadequate to sustain a pregnancy and thereby ceases ovulation to prevent conception. Research has defined a level of body fat of 11 percent as the “critical level” for the onset of menstruation. This level varies plus or minus 4 percent in many healthy, active females. During the past four years there has been an abundance of studies indicating a high incidence of menstrual irregularities among women athletes.

Evidence has demonstrated that chronic, high-intensity exercise stimulates profound changes in the menstrual cycle. At the same time, an increase in the level of testosterone in the blood stream of women who engage in strenuous physical activity has been noted. It is theorized that the mass of body fat relative to lean body weight is a critical factor in the onset of secondary amenorrhea. This condition is clinically defined as the absence or suppression of menstruation from any cause other than pregnancy or menopause.

The term amenorrheic refers to women whose menstrual cycles occur at intervals of longer than 90 days, and is the only clinical symptom to indicate a disruption of the reproductive system. Female athletes generally have a percentage of body fat lower than 20 percent, and competitive body builders can reach as low as 10 percent. The average non-athletic woman’s body fat varies between 22-28 percent, with a level of above 30 percent considered obese.

Evidence has demonstrated that chronic, high-intensity exercise stimulates profound changes in the menstrual cycle.

Factors Leading To Amenorrhea

Some of the factors which lead to the irregular occurrence of the menstrual cycle, include the following:

1. Low body fat (below 12 percent).
2. Early pre-pubertal athletic training.
3. Decreased hypothalamic activity.
4. Intensity of training regimens.
5. Reproductive maturity.
6. Stress (mental as well as physical).
7. Diet, (a high protein, low-carbohydrate diet can disrupt menstrual cycle).
8. Anabolic steroid usage: the Influx of male hormones, whether synthetic (Anavar, Deca-Durabolin, etc.) or testosterone, can wreck havoc on a woman’s body.
9. Severe exercise (heavy weight training or long-distance running).

Changes in the Body

There are several changes that occur in the female who is experiencing amenorrhea because of strenuous exercise. These include a decrease in ovarian function and metabolic and hormonal changes (the ratio of estrogens to androgens in the body).
Hormonal Changes

It is known that Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH), both of which are involved in the onset of ovulation, increase in concentration in the blood before exercise. Critical changes are taking place in the hypothalamus, and the pulse frequency of the gonadotrophin-releasing hormone is altered. All this activity is related to the changes in insulin receptor sensitivity in the hypothalamus. The potential for long-term effects on women who experience chronic amenorrhea are as follows:

A lower bone-mineral content, which can lead to reduced bone mass and the earlier onset of osteoporosis.
The potential for a female athlete’s inability to become pregnant. Studies show that women runners who develop amenorrhea have decreased spinal bone mineral content. The magnitude of the loss appears to be related to the duration of the amenorrhea.

Research at the University of California, San Francisco, was conducted to determine whether the bone loss was gradual, as in the aging process, or rapid at first and then slower, as in menopause. Bone loss (osteoporosis) makes bones easily susceptible to breaking.

One Probable Cause: Low Levels Of Calcium.

Lowered calcium levels have been found in women who restrict their carbohydrate! Caloric intake while increasing their protein intake. Research has demonstrated that high protein intake is related to lower calcium levels. Estrogen levels drop dramatically when a woman ceases to menstruate.

Forty women runners, ranging in age from 18 to 40 had their bone mineral content checked. These athletes had been experiencing amenorrhea for six months up to ten years. Those who had been amenorrheic for less than three years lost approximately 4.2 percent of their bone content during the year. The longer-term amenorrheic women lost an insignificant amount of bone. This study concluded that significant bone loss occurs during the first years of amenorrhea and tapers off in the chronic amenorrheic athlete.

It is important to stress that women athletes should consult their physicians immediately if menstruation ceases. In order to prevent irreversible bone damage, it is important to follow the directions and suggestions below.

Directions and Suggestions

The potential for side effects for women experiencing amenorrhea as a result of strenuous exercise has been found to be more pronounced in the leaner and lighter athletes. Pharmacological treatments can include prescribing Clomiphen citrate, a non-steroidal anti- estrogen drug that acts to stimulate the ovaries or estrogen replacement.

This type of intervention should be used on the advise of a gynecologist or endocrinologist, as these drugs do have potential side effects. A more sensible approach to reversing an irregular menstrual cycles (oligo-menorrhea) or a complete cessation of menses (amenorrhea) would be to follow some basic tips. Try to cycle your training by using lesser intensity during the off- season and allowing the body to return to its critical fat level (approximately 13 percent) during the off -season.

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