Exercise has another benefit: A new study finds that being active may help prevent kidney stones in women.

They don’t have to break a sweat. Even mild activity such as walking two to three hours a week cut the risk of kidney stones by about one-third.

Kidney stones are on the increase, partly because of rising obesity. About 9 percent of people will get one sometime in their life.

The study involved 85,000 women 50 and older. Those who got the equivalent of four hours of light gardening or an hour of jogging each week had lower chances of kidney stones than women who got no regular exercise.

Results were to be discussed Friday at an American Urological Association conference in San Diego.