The following, courtesy of The Age * August 12, 2008 - 7:06AM

Running can slow the aging process, according to a study conducted over two decades by American researchers and published today.

The study by the Stanford University School of Medicine found 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 per cent 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 -- 19 years after the study began, 34 per cent of the non-runners had died, compared to just 15 per cent of the runners.

I'll keep running then.