Exercise Used As Life Span Indicator
BY: By JANET McCONNAUGHEY
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 states. The study, done by researchers from the Veterans Affairs Palo Alto Health Care System/Stanford University, amounts to some of the strongest evidence yet of the importance of physical fitness.
It’s Survival Of Fittest “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 Gary J. Balady, a Boston Medical Center cardiologist. For the study, patients with and without heart trouble were given treadmill tests, which routinely are used to check people for heart trouble. In treadmill tests, patients are hooked to sensors, including a mask to measure the amount of oxygen and carbon dioxide in each breath, and 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 some 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, or MET, is defined as the amount of oxygen used by an average seated person. Using two METs is roughly equivalent to walking less than 2 mph; five METs, walking at 4 mph; and eight METs, jogging at 6 mph.
Many studies have shown fitness reduces the chance of developing heart disease and other ailments, but there have been few studies of its effect on people with heart disease, lead author Jonathan Myers said.
The researchers looked at more than 6,200 men whose 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.
The Key Is Your MET
When people were grouped by risk factors, the risk of death in people who could not get beyond four METs was more than double that of people who could get past eight METs. Aside from age, fitness was a better indicator of potential life span 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,” Balady said. The test had nothing to do with endurance – it was peak exercise capacity,said T. Edwin Atwood, one of the researchers. “It’s not how long you exercise or how long you can exercise. It doesn’t have to be marathons or running,” he said.