Fitter do live longer, study shows
The Associated Press
A person's peak exercise capacity as measured on a treadmill test is a more powerful predictor of how long someone will live than risk factors such as heart disease, high blood pressure or smoking, a study says.
"We're now beginning to prove the hypothesis of Darwin's whole 'survival of the fittest' category, in that people who are fitter tend to do better and live longer," said Dr. Gary Balady, a Boston Medical Center cardiologist.
For the study, done by researchers from the Veterans Affairs Palo Alto Health Care System/Stanford University, patients with and without heart trouble were given treadmill tests, which are used to check people for heart trouble.
In treadmill tests, patients walk on a treadmill at gradually increasing speed and angle. They continue until they are exhausted, reach their maximum heart rate, or develop chest pain or other symptom of heart disease.
The study found that a person's chances of staying alive rise 12 percent with each increase of one "metabolic equivalent" when exercising as hard as one can on a treadmill.
A metabolic equivalent is defined as the amount of oxygen used by an average seated person.
The researchers looked at more than 6,200 men whose VA doctors had referred them for treadmill testing. Some had heart disease, some did not. A total of 1,256 died during the next decade or more.
When people were grouped by risk factors, the risk of death in people who could not get beyond 4 metabolic equivalents was more than double that of people who could get past 8 metabolic equivalents.
Aside from age, fitness was a better indicator of potential lifespan than any of the other risk factors checked, such as smoking, heart problems, high blood pressure, diabetes or high cholesterol.
"Whether you have heart disease or don't have heart disease going into the test, the higher you can go on your exercise test, the better you'll do in the long run. It makes a very compelling statement in that regard," Balady said.
It also is one of the first studies showing the effect of fitness on people who already have heart disease, lead author Jonathan Myers said.
"It's not how long you exercise or how long you can exercise. It doesn't have to be marathons or running," said T. Edwin Atwood, one of the VA researchers. "Walking briskly every day for half an hour is a great risk-factor modifier."
The study found that the improvement in death rates was largest between the lowest 20 percent and the next-lowest 20 percent.