Professor Marion McMurdo, of Dundee University, said exercise could be of more benefit to the elderly than to the young.

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Writing in the British Journal of Sports Medicine, Prof McMurdo said some doctors frequently warned the elderly against exercise, despite strong evidence that it helped them maintain their independence.

The Dundee academic said the medical profession has spent too much time identifying reasons why the elderly should not exercise, fearing they would injure themselves.

It is time, she said, to unwrap the cotton wool and encourage the elderly to exercise.

Speaking to BBC Radio Scotland, she said: "The evidence suggests that older people who maintain regular physical activity and avoid smoking cigarettes are less likely to become dependent or a 'burden' in later years.

"To me that's a very powerful, persuasive argument to the older people of Scotland to start taking some regular physical exercise."

Prof McMurdo said exercise did not need to be high-tech or involve people dressing up in lycra.