It goes to show that it's never too late to take up exercising

British Heart Foundation spokeswoman

"The take-home message is you don't have to expect that you are going to function terribly in old age."

Mackey's team looked at 356 men and women aged between 70 and 96.

Volunteers answered questions about how active they were and whether they had exercised in the past two weeks.

All types of exercise were considered, including mowing the lawn and dancing.

Researchers measured the stiffness of their arteries with a technique known as pulse wave velocity.

Ms Mackey said: "When the heart beats, it creates a pressure wave and we are measuring those pressure waveforms.

"They travel faster in a stiffer artery."

Wear and tear

Surprisingly, scientists found the oldest people did not necessarily have the stiffest arteries.

Those who had taken the most exercise had the stretchiest arteries, according to an article in the American Journal of Hypertension.

A British Heart Foundation spokesman said this was further evidence of the health benefits of exercise.

She said: "This report underlines what we have known for sometime - that exercise at any age can have a beneficial effect on the health of the endothelium (the wall lining of arteries).

"It also goes to show that it's never too late to take up exercising - although older people (and those who have never exercised before) should always build physical activity into their daily routine gradually."

Ms Mackey said artery walls wear out if the heart is beating more rapidly, which happens when a person is in poor physical shape.

Although the heart rate goes up temporarily during activity, people who are frequently active have a lower overall heart rate.

Athletes have the lowest heart rates of all.

Exercise also lowers glucose levels.

Glucose or blood sugar can chemically interact with the walls of the blood vessels, damaging them and causing them to stiffen.