Female
Athletic Triad Part Two
How Heart and Brain Function are
Affected
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Part one of my series on female athletic triad was
directed toward some of the issues that can affect women in athletic training.
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, don’t 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.
Heart
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; it’s not only fat mass that has been
lost. So if the patient lost muscle that controls movement (skeletal muscle),
wouldn’t 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.
Brain circulation
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
physician’s examination is necessary. |
