Regular running appears to reduce the risk not only of heart disease, but also delay cancer and other illnesses, according to a study that began tracking people over the age of 50 back in 1984.

People who ran an average of about four hours a week when the study started were compared with a control group of healthy people who weren't regular runners. After 21 years of followup, researchers have found that everyone has more ailments, but the onset of such problems began later for the runners.

'We're all going to die some day, but we want to compress that to the final days of our life, if we can."— Kinesiology professor Jo Welch

"They begin to get the earliest forms of disability about 16 years later than do the controls," said Dr. James Fries, the senior author of the study published Tuesday in the Archives of Internal Medicine.

"They have the same or fewer knee replacements or destroyed knees. They have less musculoskeletal pain, they spend less money on medical care expenses, and by any metric that you use, they have benefited from their lifelong exercise habit."

Prolonging high quality of life

Fries, a professor of medicine at the Stanford University School of Medicine, said his findings don't stand alone and are "entirely consistent" with those of other researchers who've addressed the question. But back in 1980, it was a slightly different world.

At that time, Fries proposed a theory of aging called the compression of morbidity that was published in a journal, suggesting that we should try to prolong a high-quality life and push the onset of chronic disability as far into advanced age as possible.

He thought humans should "compress the morbidity of the average life into a shorter and shorter period between when the disability comes and when one dies."

"This was a radical change in the way people were then thinking about it, and there were no real data," he explained in an interview from Stanford, Calif.

And so Fries embarked on this project, which began with annual self-administered questionnaires filled in by 538 members of a nationwide running club and 423 healthy controls from northern California who were 50 years and older beginning in 1984.

Altogether, 284 runners and 156 controls were still in the study after 21 years. Causes of death were determined through to 2003 using a National Death Index.

Nineteen years into the study, 15 per cent of runners had died compared with 34 per cent of controls. Mortality data were available for all subjects through the death index even if participants had previously withdrawn from the study.

Hooked on vigorous exercise

As for now, Fries reported that about two-thirds of those in the running group are still running.

"The other third for the most part changed to other vigorous athletic activities, and they changed for the reasons you wouldn't have thought. They changed because they moved away or they lost their running partner — everything but knee pain. They never changed for knee pain, almost never," he said.

Some became serious swimmers or serious cyclists, or they would work out, he said. Some quit running because they were bored.

Jo Welch, assistant professor of kinesiology at Dalhousie University, said the findings by Fries and colleagues "completely make sense to me."

"If we can deal with prevention of medical treatment through looking after ourselves better, exercising vigorously, eating well, those sorts of factors, then it makes sense that we'll have reduced disability and premature mortality," she said from Halifax.

"We're all going to die some day, but we want to compress that to the final days of our life, if we can."

She mentioned one caveat. The best data would come from identical groups assigned to either run or not run for 21 years, and researchers would then know it's the exercise making a difference and not genetics or other aspects of a healthy lifestyle.

"They weren't able to do that and nobody yet has been able to do that," she observed.

As well, she noted the control group wasn't a regular sample from across America.

"They had reasonably good education, they worked at a university, so they don't include a complete cross-section of society. They don't include the migrant workers and the alcoholics under the bridge."

As for his findings, Fries said there are a number of health policy lessons that could be gleaned.

"I suppose the simplest one is that vigorous serious exercise regularly over a lifetime — swapping off into another exercise if you have some difficulty with one of the exercises — is a very, very good way to go."

Fries, who turns 70 later this month, has been running since he was 30, and has done a number of marathons. "My knees are fine," he said with satisfaction.