You will recall that if a female athlete trains hard and restricts food intake in an effort to loose weight, she may upset her normal menstrual cycle. This can lead to reduced estrogen in her system.
Estrogen is very important to many body processes beyond reproductive health. The list of systems influenced by estrogen is quite lengthy: the obvious secondary sex characteristics of females, skin, heart, blood vessels, bone, intestinal function, blood clotting, cholesterol metabolism, the kidneys' filtering of sodium and water, uterine muscle mass, and a multitude of other hormones.
(Guys, dont worry; we are not short-changed. We produce plenty of estrogen for our needs as well.)
In the triad of factors for women (nutrition, menstruation and bone health), the main concern is the effects on bone. A decline in estrogen that comes with irregular or absent menstrual periods leads to a reduction in bone density. The pounding that comes with training can lead to stress fractures of bones in particular the tibia and foot bones.
But estrogen has more wide-ranging effects. Two areas of the cardiovascular system also are affected by a reduction in estrogen: the heart and the blood vessels of the brain.
Now this might sound like taking things to the extreme. Anorexic patients are studied to learn how their body has adapted to severe caloric restriction. Everyone knows they have lost weight, but much of the weight loss is as muscle mass; its not only fat mass that has been lost. So if the patient lost muscle that controls movement (skeletal muscle), wouldnt it make sense that other muscle is also lost?
The muscle of the heart is very similar to skeletal muscle and also is reduced, pretty much in proportion to the amount of skeletal muscle loss. What appears to happen is that some of the tissue between cardiac muscle cells becomes filled with what is called fibrous tissue, and this fibrous tissue might be at the core of why some anorexics have heart problems. Has this been proven in training females who have been diagnosed with the triad? Not yet. But we've all seen some very lean and skinny distance runners. It is possible that they may have some alterations in their heart cells as well.
Believe it or not, there is an accepted clinical method to produce a standard blow to the head of a rat. The procedure is quite involved. When male and female rats are submitted to this impact, they respond differently: Male rats are far more affected by the impact than female rats. Researchers have taken a group of female rats that have had their ovaries surgically removed (and all hormones but estrogen replaced) and performed this same impact. Guess what? The results of the impact in these female rats are almost the same as the results of the impact in male rats. Estrogen protects the head from this method of impact. The area of the brain that has its function altered by the loss of estrogen governs the circulation of blood meaning the integrity of the blood vessels is influenced by estrogen.
There is very little data on gender differences in head injuries in athletes. One survey of about 140 national-class soccer players showed that around half the men had a history of concussion while about one-quarter of the women had a concussion history.
Much more research needs to be done on gender differences in head injuries, but it is not much of a jump to see that a woman who is under the effects of the triad may be placing more than her bones at risk; her heart and brain may also be at risk.
As stated last time, never assume that a change in menstrual function in a female athlete is due to training alone. A physicians examination is necessary.
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