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Does Breaking a Sweat Reduce Breast Cancer Risk?

Many studies have shown that exercise and physical activity lower the risk of breast cancer. But how much exercise is enough? And what kinds of activity are best?

The first study to look at all types of activity over a woman's lifetime has been reported. A large number of women up to age 80 were included. Each participant filled out a survey and was interviewed. Activities at work, home, and play were evaluated. Women were asked to report what kinds of activity they did, for how long, and how vigorously. Light activity was defined as anything that was easy to do while standing or walking slowly. Moderate activity increased the heart rate and caused a light sweat. Heavy activity increased the heart rate and caused heavy sweating.

Which kind of activity reduces the risk of breast cancer? Is it how long a woman exercises? How hard? How many years she does it? It seems the intensity of the activity (getting the heart rate to go up and breaking a light sweat) makes a difference. Light or vigorous activities did not lower the risk of the women who took part in this study. The authors thought this might be because most women in the study did not exercise vigorously or did not remember to report easier activities.

At the moment, it looks like lowered risk for breast cancer occurs with work and household activities. These activities must be of moderate intensity over a lifetime. According to this study, recreational activities at any intensity level do not lower breast cancer risk. But for those of you who have traded in the couch for a bowling bowl, don't despair. Scientists admit they don't know what it is about certain activities that helps reduce risk. More studies may yet find the answer and show which recreational activities are best.

References: Christine Friedenreich, PhD, et al. Relation Between Intensity of Physical Activity and Breast Cancer Risk Reduction. In Medicine & Science in Sports & Exercise. September 2001. Vol. 33. No. 9. Pp. 1538-1545.

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