英語(yǔ)時(shí)差：鍛煉減少乳癌

If you're not already convinced that regular exercise is important to stay healthy, now there is yet another reason to break a sweat, especially if you're a woman: breast cancer. Several studies have linked exercise to lowering the risk of developing breast cancer. Considering that breast cancer is the second most common cancer among women, these findings are nothing to shrug about. First, regular exercise reduces the risk of breast cancer by helping women to maintain a healthy and consistent body weight. Post-menopausal women who have gained more than twenty pounds since the age of eighteen are forty percent more likely to develop breast cancer. Women who gain seventy or more pounds in their adult years are eighty percent more likely to develop breast cancer.

Another study suggests that the correlation between breast cancer and body weight may have much to do with female hormones produced by body fat. Higher levels of estrogen, as well as testosterone, have been demonstrated to increase one's risk of developing breast cancer. However, exercise significantly reduces the levels of these hormones by burning body fat, which produces the hormones. So the more you exercise, the more fat you burn, hence the lower your hormone levels, and the lower your risk of developing breast cancer.

How much exercise is necessary? Just thirty minutes of exercise each day or three to four hours a week could lower one's risk of breast cancer by about twenty percent. And exercising more than four hours a week may further lower your risk.

Keep in mind, however, that no amount of exercise can guarantee you won't develop cancer. Certain risk factors such as genetic make-up and environmental exposures are uncontrollable.