Female Athletic Triad Part One
When Three Key Factors Fall Out of Balance

Part Two of the series is: Cardiovascular and neurological problems of low estrogen

In the vast majority of sports, men and women compete on a level field. For the most part, both sexes use the same timers, same distances, same rules, etc.

Thus, coaches of women’s teams adopt many of the training procedures used for men. The problem is that while the games and rules are the same, the physiology of each sex is different, and what works for a man might not be as effective for a woman — or worse, the training might actually lead to injuries in women.

Concern for just this problem has been an interest of many researchers, coaches and athletes when it became apparent that women athletes suffered many more stress fractures of certain bones (typically tibia and foot bones) than men.

So, if the training was the same, why were women suffering these injuries? The result lead to an understanding of the interaction of three factors — the female athletic triad unique to training women: nutrition, menstruation and bone health.

The general assumption is that the lighter an athlete, the faster they will be. So in sports were speed is an issue, carrying excess body fat is a liability. Therefore, many women athletes will try to lose body fat to become more efficient. The problem is that women tend to try to lose weight during the time of year of greatest workload — in season. In addition, to speed up weight loss, they will limit their dietary intake.

Both factors are happening at the wrong time — in season (if weight loss is needed or desired, do it in the offseason). As a result, they end up in a negative calorie balance — they expend more calories (exercise) then they take in (dieting).

A second factor that happens during some women's training is a disruption of the normal menstrual pattern. This can be due to training overloads, caloric deficits, or a host of clinical problems. (Never assume that menstrual irregularities are due to training. Always consult a physician.) When this happens, the normal cycling of estrogen is upset, and estrogen is an important hormone for more than just reproductive health.

The third factor is bone density. Normally, bones become denser (stronger) with weight bearing (i.e. running). There is another factor that is necessary for improving bone density. That’s right: estrogen. In the absence of estrogen, bone density decreases to the point where excessive loads (training) actually cause the bone to break down. Normally, such problems don’t start happening until menopause, but women athletes with the triad may have bones with the density of a woman many years older.

What appears to be happening is that when a training female athlete limits her caloric intact, the body has to make some decisions. Does it continue to channel the limited fuel intake to menstrual function, or to the muscles for training? If the body chooses the muscles, then reproductive health is pushed into the background, leading to a disruption of normal menstruation and a decline in estrogen levels.

This then leads to a decrease in bone density, with the results being stress fractures. This concept has been referred to as the "energy drain hypothesis."

So how do women avoid the triad? First and foremost is to maintain a healthy diet and don’t try to lose weight during the season. Second, ramp up training slowly. A rapid increase in training is a quick path to injury.

But there is more to this than just stress fractures of bones.

Next: Cardiovascular and neurological problems of low estrogen