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The Survival of the Fittest
Natural selection is a cold and harsh process. Animals that become
weak, slow, or sick become vulnerable to elimination. These individuals
are usually the first to be culled from the herd by predators or harsh
conditions. For most of the existence of the human race, physical fitness
was not an option. The weakest and slowest members of the tribe were the
most susceptible to predators, severe elements, and times of scarcity.
Today you do not have to worry about falling prey to wild carnivores,
famine, or the elements. But even in highly civilized 21st century
America, when you become weak, out of shape, or unfit you better 'watch
your back'. Natural selection is still culling the herd, though it won't
be lions or wolves nipping at your heels and dragging you down. The modern
predators are heart disease, cancer, osteoporosis, diabetes, and many
other forms of disease.
I really worry about my patients who become so weak that they can no
longer perform their normal daily activities like climbing the stairs,
doing housework or yard work. Sure, we have all seen examples of very fit
and strong people who succumbed to a premature death from heart disease or
cancer, but much more often disease strikes the weak and unfit
individuals.
A study published recently in the New England Journal of
Medicine found that being out of shape (or unfit) was more
dangerous than all of the other classic risk factors such as smoking, high
blood pressure, and established heart disease. That trial showed that a
person's exercise capacity, measured simply by how long they could walk on
a treadmill, was a more powerful predictor of death than all other risk
factors. It also showed that regardless of what risk factors you may have,
when you become physically fit you decrease your risk of premature death
by 50 percent.
Most of this benefit is realized by going from a completely sedentary
lifestyle to being just moderately active. This means simply making a
habit of taking the stairs rather than the elevator, taking your dog for a
stroll one or two times a day, or doing vigorous housework can
substantially reduce your risk of dying. The more fit you become, the
lower the risk that you will fall prey to the modern scourges. For
instance, studies show that people with significant plaques in the heart
arteries can markedly reduce their risk of heart attack by walking or
jogging 15 miles per week. The people who increase the distance to 20 or
more miles weekly have an even lower risk of heart trouble.
In fact, exercise is a great way to prevent heart attack, stroke, and
even some forms of malignancy like colon cancer. Studies show that being
sedentary is linked to a host of serious health problems - from depression
and diabetes to osteoporosis, dementia, and even sexual dysfunction. Yet
almost 75 percent of adults in the United States are now considered unfit,
and 65 percent are overweight or obese. I personally find this concept of
natural selection a great motivational tool to 'train for life.' Our very
survival may depend on our ability to stay strong and fit. In the
meantime, exercise also keeps us lean, enthused and vigorous.
© 2005, Cardiovascular Consultants.
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