The study by the Stanford University School of Medicine found that people over 50 who ran regularly over several years suffered fewer disabilities, had a longer span of active life and reduced their risk of dying early by 50 percent compared to those who were inactive.
"The study has a very pro-exercise message," said James Fries, MD, an emeritus professor at the medical school and the study's senior author.
"If you had to pick one thing to make people healthier as they age, it would be aerobic exercise."
The study, published in the Archives of Internal Medicine, tracked 538 people over 50 who had run several times a week since 1984 and compared them to a similar group of non-runners.
As the subjects aged, the health gap between the runners and non-runners widened, continuing even into their 90s.
"We did not expect this," said Fries, 69, himself an avid runner. "The health benefits of exercise are greater than we thought."
He attributed this to runners having a leaner body mass and generally healthier habits.
Running's effect on delaying death also was more dramatic than the researchers had expected -- nineteen years after the study began, 34 percent of the non-runners had died, compared to just 15 percent of the runners.