Skip to content

Fitness & Exercise

Font Size

Modest Exercise Lowers Breast Cancer Risk

Less Than 3 Hours a Week Offers Protection Close to Longer Workouts
WebMD Health News

Sept. 9, 2003 -- Even a little exercise may offer big protection against breast cancer.

A new study shows that walking briskly for less than three hours a week reduces the risk almost as much as longer workouts.

Researchers looked at 74,000 women enrolled in the ongoing Women's Health Initiative. They found that exercising a mere 1 1/4 to 2 1/2 hours each week -- walking briskly or similar exercise -- reduced the risk of breast cancer by 18% compared with inactive women. That protective effect is only slightly less than the 22% reduced risk observed in women who exercise at least 10 hours a week.

You Don't Have to Be an Athlete

"This is great news for women who don't want to be athletes," says lead researcher Anne McTiernan, MD, PhD, of the Fred Hutchinson Cancer Research Center in Seattle. "Even modest exercise can reduce their risk of breast cancer."

The benefits of exercise on breast cancer are well established, with more than 30 studies showing that women who regularly engage in physical activity have significantly less breast cancer. But most of those studies show protection resulting from more vigorous levels of activity -- typically starting at the often-recommended 30 minutes per day.

But this new study, published in this week's edition of TheJournal of the American Medical Association, shows that even moderate intensity exercise done regularly -- say, walking at a 20-minute-per-mile pace -- may offer significant breast cancer protection.

"Some of the older studies made it look like women had to do vigorous activity in order to reduce their risk," McTiernan tells WebMD. "But it looks like light, brisk walking done a few days a week may also offer significant benefit."

Even for Those at Highest Risk

There is a caveat, though: This lower risk is more likely to occur in women who are thin, average, or only slightly overweight -- especially as they reach middle age and beyond. Modest or even more intense exercise alone plays little, if any, role in reducing cancer risk in the obese, she says.

"Exercise works in reducing breast cancer risk by reducing body fat, which itself is a risk factor," says McTiernan, a longtime breast cancer researcher who authored Breast Fitness: An Optimal Exercise and Health Plan for Reducing Your Risk of Breast Cancer. "But if body fat levels are not low enough, even if women are overcompensating with exercise, they're not getting the same benefit. They also need to diet in order to lose that body fat."

Healthy Living Tools

Ditch Those Inches

Set goals, tally calorie intake, track workouts and more, all via WebMD’s free Food & Fitness Planner.

Get Started

Today on WebMD

pilates instructor
15 moves that get results.
woman stretching before exercise
How and when to do it.
couple working out
Moves you can do at home.
woman exercising
Strengthen your core with these moves.
man exercising
knees to chest
Man looking at watch before workout
Overweight man sitting on park bench

Pollen counts, treatment tips, and more.

It's nothing to sneeze at.

Loading ...

Sending your email...

This feature is temporarily unavailable. Please try again later.


Now check your email account on your mobile phone to download your new app.

pilates instructor
jogger running among flowering plants
woman walking
woman doing pushups