Posted: Jun 27, 2012 10:57 AM
A study published earlier this week in the journal Cancer indicates even mild to moderate exercise started later in life lowers breast cancer risk in women.
Researchers looked at exercise, weight and breast cancer risk in more than 3,000 women ages 20 to 98 who participated in the National Cancer Institute's Long Island Breast Cancer Study Project. Women who reported 10 to 19 hours of weekly exercise during child-bearing or post-menopausal years experienced about a 30 percent lower breast cancer risk compared to inactive women. Exercise was even beneficial to heavy women who were not losing weight.
"Heavy women can still exercise, and even if they're not losing weight, the exercise is still helping them," Dr. Michelle Holmes, an epidemiologist at Harvard School of Public Health said.
The study also indicates exercise duration is more important than intensity. Lauren McCullough, an epidemiologist at the University of North Carolina, Chapel Hill, said even relatively mild forms of exercise such as walking the dog or taking the stairs provides benefits.
"You don't have to be in the gym running on the treadmill, and it doesn't all have to be 10 consecutive hours," she said.
Researchers say exercise as women gets older provided the most benefit. Workouts during adolescence and early adulthood showed no effect.
"It's not saying that that early exercise is harmful. After all, that's when you form your habits," Holmes said. "It probably has to do with lowering hormone levels that may not even be in play until the reproductive years or later."
McCullough says the study gives a clear message - start exercising early and keep it up.
"From a public health perspective, I would recommend you should always be active from adolescence," she said. "But the results of this study say it's never too late to start."