The Dangers of Too Much Exercise

By Jason Girdon

Special to CSMS Magazine

When Dr. Kenneth H. Cooper was writing his first fitness book, Aerobics, back in 1968, He believed that a regimen of sustained, strenuous exercise was necessary for health and longevity… and more was better. In the decades since then, countless studies have helped to radically refine this basic “exercise prescription.”

It has become increasingly clear that the health benefits of less exercise—less strenuous and less time consuming—are almost as great as a very demanding workout program.

We’ve also learned that excessive exercise exacts a toll on our bodies—in the form everything from musculoskeletal injuries to increased risk of cancer, heart attack, arthritis, and other diseases.

How Much Exercise Is Best?

In 1989, Steven Blair, PED, a researcher here at The Cooper Institute, shook the scientific world.

In measuring the fitness of more than 13,000 American men and women, Blair found than 20% who were fittest were 75% less likely to die over the next eight years than the 20% who were least fit. No surprise there.

The shock was that the biggest reduction in mortality came from only a slight increase in exercise. Those who were just a tad filter than their most sedentary peers enjoyed a 55% lower death rate.

Implication: Very moderate physical activity gives the biggest health return on your investment of time and energy. A modest exercise regimen confers increased energy and endurance and a stronger, more resilient cardiovascular system. This “aerobic training effect” lowers your risk of disease…and raises your life expectancy by up to two-and-one half years.

Now there is a strong believe that there’s no health-related reason to do anything more strenuous activities like mountain climbing, skiing and an occasional five-kilometer running race.

Why More Isn’t Better

People who exercise harder than this may be doing themselves more harm than good. I’m talking especially about the individuals who run 30 miles a week or more.     For starter, the risk of muscle injury steeply once you run much than 15 miles a week. Most people who used to work out at this level have had to cut sharply because of chronic injuries. Many of those who kept running long distances eventually had to quit altogether. Some required hip or knee replacements.

But muscle and joint problems are just the beginning. It turns out that serious exercisers may be unusually vulnerable to life-threatening illnesses. In Dr. Cooper’s practice, he’s seen many cases of cancer and heart disease among elite athletes. Studies examining the relationship between exercise and health, like Dr. Blair’s, indicate that the death rate goes up slightly for those at the peak of the fitness pyramid.

What’s to blame? The most likely culprit is a class of highly unstable.