Postmenopausal women who engage in regular physical activity are known to be less likely to develop breast cancer. Increased physical activity reduces levels of estrogens in postmenopausal women, and thus may reduce the risk of breast cancer.
Women who exercised experienced significant declines in blood levels of the female hormones estrone, estradiol, and free estradiol.
Fat mass decreased in exercisers and greater losses of body fat were associated with larger decreases in blood hormone levels.
“Exercise could lower breast cancer risk in postmenopausal women by reducing body fat and ultimately circulating estrogen concentrations” lead researcher Dr. Anne McTiernan – Fred Hutchinson Cancer Research Center in Seattle.