Just a little exercise each week - jogging for an hour or walking for about three hours - can reduce the risk of developing kidney stones by up to 31%, according to a new study. Researchers looking at data on more than 84,000 postmenopausal women found that engaging in any type of light physical activity can help prevent the formation of these pebbles in the kidneys. Even light gardening might curb their development, according to the study, which was published in the Journal of the American Society of Nephrology. "Even small amounts of exercise may decrease the risk of kidney stones," said study author Dr. Mathew Sorensen, of the University of Washington School of Medicine. "It does not need to be marathons, as the intensity of the exercise does not seem to matter." Kidney stones, which have become increasingly common, are more prevalent among women. During the past 15 years, research has shown that kidney stones might actually be a systemic problem, involving more than just the kidneys. Recent research has linked the stones to obesity, diabetes, metabolic syndrome and heart disease. In conducting the study, the researchers analyzed information compiled since the 1990s on the women's eating habits and level of physical activity. After taking into account the women's body-mass index (a measurement of body fat based on a ratio of height and weight), the researchers found that obesity was a risk factor for the development of kidney stones. Eating more than 2,200 calories a day could increase the risk for kidney stones by up to 42%, they found.