This is the first study on the effects of moderate exercise and in the consequence of whether or not less active females who start exercising can get similar results.

The study reported on 100,000 subjects who had reached postmenopausal period of their lives and followed their progress for a period of 20 years.

During this period, women told how active they were in their lives and the type of exercises they had.

A. Heather Eliassen and her team at Harvard reviewed data in the Archives of Internal Medicine and the many risk factors for breast cancer that women have no control on.

These included family history of the disease or the age at which they began menstruating, the researchers told Reuters Health.

The team believes physical activity “is one of the few breast cancer risk factors that women can do something about. And it’s never too late.”

Those women who had at least an hour of brisk walking every day, or the same amount of activity per day, were 15 percent less likely to develop breast cancer than those who walked less than one hour per week.

The group defined brisk walking as walking at about three to four miles per hour — a speed at which it is hard to keep a conversation while walking.