Exercise intensity and breast cancer risk

WaPo reports:

Vigorous activity can reduce the risk of breast cancer by about 30 percent in normal-weight women, according to an 11-year U.S. study of 32,269 postmenopausal women.

For the study, vigorous activity was defined as heavy housework (scrubbing floors, washing windows, demanding yard work, digging, chopping wood) and strenuous sports or exercise, such as running, fast jogging, competitive tennis, aerobics, bicycling on hills, and fast dancing.

While vigorous activity reduced breast cancer risk in normal-weight women, it had no effect in women who were overweight or obese, according to study leader Michael F. Leitzmann and colleagues.

They also found that non-vigorous activity, such as light housework (vacuuming, doing laundry, painting, general gardening) and light sports or exercise (walking, hiking, light jogging, recreational tennis, bowling) offered no protection against breast cancer.

For a long time, the medical establishment has backed the view that modest exercise is sufficient to realize the protective effects against a variety chronic illnesses. In fact, study after study is showing exercise to be far more effective in reducing the incidence of many chronic diseases than almost any dietary change -- except maybe frequent fasting or a calorie restricted diet.

This study is interesting because it suggests that only intense regular exercise is protective against breast cancer.