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How hard you can exercise is best predictor of longevity

Living on the Couch is Living on the Edge

By Chris Vaughan
Illustration Philippe Weisbecker

The life of a couch potato turns out to be a risky proposition, say researchers at Stanford University Medical Center and the Veterans Affairs Palo Alto Health Care System. The researchers offer particularly compelling evidence that being out of shape correlates with a higher risk of death. More specifically, their study, published in the May 14, 2002, issue of the New England Journal of Medicine, shows that your ability to push yourself hard when exercising is a better predictor of longevity than any other common measure.

For instance, how hard you can exercise is a better measure of longevity than how much you smoke or whether you have hypertension or diabetes, says lead author Jonathan Myers, PhD, a VA Palo Alto researcher. And exercise capacity also did better at predicting survival than other measurements, such as peak heart rate.

In the study, the researchers measured peak exercise capacity of 6,200 men and related that data to the subjects’ mortality over 10 years. Victor Froelicher, MD, professor of medicine at the VA, began collecting the data more than a decade ago and worked with Myers, Eddie Atwood, MD, professor of medicine at the VA, and colleagues to analyze the findings.

For the Vigorous, the End is Not Quite So Near

Many studies have shown that improving fitness can lower your risk of cardiovascular disease, and still others have shown that if you have heart disease, exercise capacity is a good indicator of mortality. But this is the first study to correlate exercise capacity and mortality in people who don’t have cardiovascular disease as well as those who do. “What we found was that exercise capacity is similarly important in both groups,” says Myers.

In the study, the men were put on a treadmill that increased in speed and angle until they could no longer run or started to feel chest pains. Their maximum effort was measured in “metabolic equivalents” or MET. One MET is the amount of oxygen the average person uses while sitting down, while five MET is about what one consumes while walking at 4 mph, and eight MET is what most people consume while jogging at 6 mph.

The team found that for every MET increase in a man’s exercise capacity, the risk of mortality dropped by 12 percent.

Those with a maximum capacity of less than five MET had double the chance of dying (from any cause) of those with an exercise capacity of eight MET or more.

The authors did point out qualifiers to their study. Because it included only men, they don’t know if results apply equally to women. Furthermore, while they have shown a relationship between exercise capacity and mortality, they cannot reveal if the relationship is causal — that is, whether improving exercise capacity directly decreases chances of dying.

Still, the study’s authors say, the available evidence is enough for physicians and patients to act upon. “In terms of reducing mortality from any cause, improving exercise tolerance warrants at least as much attention as the other major risk factors for patients who have cardiovascular disease or are at high risk for it,” Myers says.

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