Running on a regular basis can slow the effects of ageing, a study by US researchers shows.
Elderly joggers were half as likely to die prematurely from conditions like cancer than non-runners.
They also enjoyed a healthier life with fewer disabilities, the Stanford University Medical Center team found.
Experts said the findings in Archives of Internal Medicine reinforced the importance that older people exercise regularly.
Survival of the fittest
The work tracked 500 older runners for more than 20 years, comparing them to a similar group of non-runners. All were in their 50s at the start of the study.
Nineteen years into the study, 34% of the non-runners had died compared to only 15% of the runners.
Both groups became more disabled with age, but for the runners the onset of disability started later - an average of 16 years later.
The health gap between the runners and non-runners continued to widen even as the subjects entered their ninth decade of life.
Running not only appeared to slow the rate of heart and artery related deaths, but was also associated with fewer early deaths from cancer, neurological disease, infections and other causes.
And there was no evidence that runners were more likely to suffer osteoarthritis or need total knee replacements than non-runners - something scientists have feared.
At the beginning of the study, the runners ran for about four hours a week on average. After 21 years, their weekly running time had reduced to around 76 minutes, but they were still seeing health benefits from taking regular exercise.
Lead author Professor James Fries, from the University of California at Stanford, said: "The study has a very pro-exercise message. If you had to pick one thing to make people healthier as they age, it would be aerobic exercise.
"The health benefits of exercise are greater than we thought."
Age Concern says many older people do not exercise enough.
Figures show more than 90% of people in the UK over 75 fail to meet international guidelines of half-an-hour moderate intensity exercise at least five times a week.
Gordon Lishman, director general, said: "This research re-confirms the clear benefits of regular exercise for older people.
"Exercise can help older people to stay mobile and independent, ensure a healthy heart, keep weight and stress levels under control, and promote better sleep.
"While younger people are barraged with encouragement to lead healthier lifestyles, the health needs of older people are often overlooked."
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