US scientists comparing middle aged and older regular runners with healthy equivalents for more than 20 years found that vigorous regular exercise was linked to longer life and less disability in old age.
The study was the work of Dr James Fries and colleagues, based at the Division of Immunology and Rheumatology in the Department of Medicine at Stanford University School of Medicine in California and is published in the Aug 11/25, 2008 online issue of the Archives of Internal Medicine.
Fries, who is an emeritus professor of medicine at the medical school and senior author of the study, said:
“The study has a very pro-exercise message.”
When they started the study in 1984, research was already showing strong links between exercise and many health outcomes for people of all ages, but there were no long term studies on older adults that looked at the effect on disability and longevity.
Back then many experts were of the opinion that strenuous exercise was likely to do older people more harm than good, fearing that the then still new craze for jogging would result in floods of admissions of older people with orthopedic injuries.
But Fries and his team had a hunch this would not be the case, that in fact exercising regularly would be linked to higher quality life that was more likely to be free of disability for longer. They suggested that by keeping the body moving, people wouldn’t necessarily live longer, but the length of time toward the end of life when they would not be able to carry out the daily tasks of living would be much shorter. This became known as the “compression of morbidity theory”.
So Fries and his team had 538 members of a nationwide running club and 423 healthy controls from northern California fill in questionnaires every year for as long as they could, from 1984 to 2005, when there were 286 runners and 156 controls still in the study.
The participants were aged 50 and over at the start of the study, and the data gathered included how often they ran and exercised, body mass index (BMI), and disability level (using the HAQ disability index score of 0 for none through to 3 for unable to perform). The disability index assesses ability to do basic every day things like walking, dressing and grooming, getting out of a chair and gripping objects.
For those who died during the study, Fries and colleagues obtained cause of death from a national register.
The researchers then performed statistical tests like multivariate regression analysis on the data to compare the two groups. The results showed that:
- At the start of the study (baseline), the runners were leaner, and less likely to be smokers than the controls.
- At baseline, the runners ran an average of 4 hours a week. After 21 years, they were running an average of 76 minutes a week.
- The mean disability score was higher for the controls than the runners at all stages of the study and went up with age in both groups, but on average, for runners the onset of disability started later.
- Runners had a significantly lower risk of having a disability score of 0.5.
- 19 years into the study, 15 per cent of the runners and 34 per cent of the controls had died, and after adjusting for possible confounders, runners showed a greater chance of living longer.
- The differences in disability and longevity between the runner group and the control group continued to diverge at the end of the study, as the participants approached their 80th birthday.
The researchers concluded that:
“Vigorous exercise (running) at middle and older ages is associated with reduced disability in later life and a notable survival advantage.”
Commenting on the results, Fries said:
“Runners’ initial disability was 16 years later than nonrunners.”
“By and large, the runners have stayed healthy,” he added. Not only did the running appear to delay disability but the gap between the runners and the controls got bigger with time, a feature that surprised the researchers, “the health benefits of exercise are greater than we thought,” said Fries.
Even as the participants entered their ninth decade of life, the gap continued to widen, an effect which the researchers put down to the runners’ greater lean body mass and healthier habits. But Fries said he didn’t think the effects would go on for ever, “we know that deaths come one to a customer. Eventually we will have a 100 percent mortality rate in both groups,” he said.
But there is no denying that the effect of running has been much bigger than the researchers expected. While as expected it slowed cardiovascular deaths, unexpectedly it was also linked to fewer early deaths from cancer, neurological disease, and other causes like infections.
As for the idea that running in old age would bring a flood of injuries, that fell completely flat. Fries and colleagues have also published another study about this in the August issue of the American Journal of Preventive Medicine where they showed that running was not linked to greater rates of osteoarthritis in the elderly runners and they did not require more total knee replacements than nonrunners.
Fries said:
“Running straight ahead without pain is not harmful.”
He explained that running appears in fact to be safer for the joints than high-impact sports like football, or standing in unnatural positions like en pointe in ballet. Fries said people were skeptical about their ideas when they started the research, but nowadays, more and more studies are showing the same results.
Fries, who is 69, is an accomplished runner, mountaineer and outdoor adventurer.
“Reduced Disability and Mortality Among Aging Runners: A 21-Year Longitudinal Study.”
Eliza F. Chakravarty; Helen B. Hubert; Vijaya B. Lingala; James F. Fries
Arch Intern Med. 2008;168(15):1638-1646.
Vol. 168 No. 15, Aug 11/25, 2008
Sources: Journal Abstract, Stanford School of Medicine.
Written by: Catharine Paddock, PhD