Exercise cuts the risk of developing breast cancer. But, just how much exercise is required to reduce the risk? A new study has provided some answers to this question.

The researchers found that women who exercised for 10 to 19 hours a week (around 1.5 to 2.5 hours a day) had 30 percent reduced risk of developing breast cancer. The results were same for women in reproductive and post-menopausal age. Intensity of exercise wasn't found to be a factor associated with breast cancer risk reduction.

Moderate exercises were found to be as effective as intense exercises. However, gaining weight was seen to negate the benefits of exercises.

"The observation of a reduced risk of breast cancer for women who engaged in exercise after menopause is particularly encouraging given the late age of onset for breast cancer," said Lauren McCullough, doctoral candidate at the UNC Gillings School of Global Public Health and lead author of the study.

More than 3000 women participated in the study. Of these 1,504 were diagnosed with either invasive or non-invasive breast cancers. The 1,555 other participants of the study group had no known cancers. Age of the participants was between 20 and 98. They all were part of Long Island Breast Cancer Study Project.

The study also showed that intensity was not a factor suggesting that even moderate or light exercise will reduce the risk of breast cancer. The study is particularly encouraging because exercise may affect hormone receptor status which reduces the most common types of breast cancer, hormone receptor positive breast cancers.

Weight gain may eliminate the risk reduction. The researchers found that women who were physically active but gained a significant amount of weight had an increased risk of developing breast cancer. This increased risk was especially true for women after menopause.

Experts believe that moderate exercise helps reduce risk of many diseases including stroke, diabetes, heart disease , Alzheimer's to name a few. Any kind of moderate to intense activity reduces risk of diseases in people above 40 years of age. Although genetic factors play an important role in determining what diseases people get, adopting healthier lifestyle does reduce the risk of getting a particular disease.

The study was published in Cancer.