Couch potatoes who start exercising in later life can still significantly cut their chances of developing coronary artery disease, suggests a small study published ahead of print in Heart.

The authors base their findings on 312 adults between the ages of 40 and 68 who had confirmed coronary artery disease and 479 volunteers matched for age and sex.

Each participant was interviewed about their level of physical activity in early adulthood, classified as the period between 20 and 39, and in late adulthood, defined as the period after the age of 40.

Unsurprisingly, known risk factors for coronary heart disease, including smoking, diabetes, and high blood pressure tended to be more common among those with confirmed disease.

Around half of those with heart disease and seven out of 10 of the healthy volunteers said that they had been moderately or very physically active in younger and older adulthood.

But around one in 10 of those with confirmed disease and around one in 20 of the healthy volunteers confessed to having enjoyed a lifetime of physical inactivity.

Those who had been active all their lives had the lowest risks. They were around 60 per cent less likely to be diagnosed with coronary heart disease.

But those who became very physically active after the age of 40 were around 55 per cent less likely to be diagnosed with heart disease than those who had embraced inactivity all their lives.

The authors conclude that while optimal health is likely to be enjoyed by those who exercise all their lives, it is not too late to start. Regular exercise, even if started in older life, still confers many benefits and substantially cuts the risk of heart disease.

But an accompanying editorial points out that only about a third of men and a fifth of women in England manage the recommended 30 minutes of moderate physical activity on most days of the week.

And these proportions fall to just 17 per cent and 12 per cent, respectively among those aged 65 and above, it says.