Alpa Patel, senior epidemiologist at the American Cancer Society in Atlanta, said the study of 73,615 postmenopausal women found women who engaged in at least an hour of vigorous physical activity every day had a 25 percent lower risk for breast cancer, while those who walked for at least seven hours a week had a 14 percent lower risk for breast cancer.
"We examined whether recreational physical activity, specifically walking, was associated with lower breast cancer risk. Given that more than 60 percent of women report some daily walking, promoting walking as a healthy leisure-time activity could be an effective strategy for increasing physical activity among postmenopausal women," Patel said in a statement.
"We were pleased to find that without any other recreational activity, just walking an average of 1 hour per day was associated with lower risk of breast cancer in these women."
The researchers determined the observed benefits of physical activity and walking were not influenced by body type -- body mass index and weight gain -- or hormonal status, or postmenopausal hormone use.
"Current guidelines recommend that adults should strive to get at least 2.5 hours per week of moderate-intensity activity, or 75 minutes per week of vigorous-intensity aerobic activity for overall health," Patel said. "Higher levels of activity might provide greater benefit for breast cancer prevention."
The researchers also found about 9.2 percent of the participants did not partake in any physical activity, while about 47 percent reported walking as their only activity.
The findings were published in Cancer Epidemiology, Biomarkers & Prevention.
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