Women who walk for an hour a day can cut their risk of breast cancer in later life, say researchers.
Taking a brisk stroll can dramatically reduce the chances of developing the disease in women over 50, the period at which they are most at risk.
Just 60 minutes of so-called moderate activity a day led to a 14 per cent lower risk compared to women who were less active, a study revealed.
And women who did more vigorous activities got almost double the protection, cutting their risk of breast cancer by a quarter.
Previous studies have shown the benefits of exercise, but scientists claim the latest research is the first to examine walking.
It is thought to help cut down the body fat that can produce cancer-stimulating hormones such as oestrogen and insulin.
Scientists at the American Cancer Society studied 73,615 post-menopausal women, of whom 4,760 were diagnosed with breast cancer during a 17-year follow-up.
Among all women in the group, 47 per cent said walking was their only recreational activity.
Of that group, those who walked at least seven hours a week had a 14 per cent lower risk of getting breast cancer compared to those who walked three hours or fewer every week.
The study also found that women who took part in more vigorous exercise for an hour each day had a 25 per cent lower risk of developing the disease than the least active.