Walking just four hours per week can dramatically reduce the risk of breast cancer, according to a recent study Live Science reported.

Researchers found that older women who had engaged in regular physical activity, equivalent to at least four hours of walking per week, had a 10 percent decrease in their risk for developing breast cancer compared with women who exercised less, including those who didn't exercise at all.

"The results of our study are consistent with the World Cancer Research Fund recommendation of walking 30 minutes per day," study author Agnès Fournier, a researcher at the Centre for Research in Epidemiology and Population Health at the Institut Gustave Roussy in France, is quoted as saying by Live Science. "The study also indicates that engaging in vigorous or very frequent activity is not necessary to receive the protective benefits of exercise."

For the study, researchers collected and analyzed data from more than 59,000 postmenopausal women from 1993 to 2005. They completed biennial questionnaires and reported their levels of physical activity in 1993, 1997 and 2002. At a follow-up nearly nine years later, the researchers determined that 2,155 of the women had been diagnosed with invasive breast cancer.

"The literature reporting the association between regular physical activity and reduced breast cancer risk after menopause has been pretty consistent," Fournier told Live Science. "In our study, we wanted to examine how rapidly this association is observed after regular physical activity is begun and for how long it lasts once women stop exercising."

The findings also illustrate that the benefit of exercise dropped women stopped being active.

"Women who engaged in this level of physical activity between five and nine years earlier, but who were less active in the four years prior to the study, did not have a decreased risk for invasive breast cancer," Fournier said.

The findings were recently published in the journal Cancer Epidemiology, Biomarkers & Prevention.