Previous studies have shown that breast cancer survivors who meet the current exercise recommendations (2.5 hours of moderate intensity physical activity per week) are at 25% lower risk for dying from breast cancer. New research from the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and reported in the International Journal of Cancer suggests that exceeding the recommendations may provide greater protection, and that running may be better than walking.
The study, by Berkeley Lab's Paul Williams of the lab's Life Sciences Division, followed 986 breast cancer survivors as part of the National Runners' and Walkers' Health Study. Thirty-three of the 714 walkers and 13 of the 272 runners died from breast cancer over 9 years. When analyzed together, their risk for breast cancer mortality decreased an average of 24% per metabolic equivalent (MET) hours per day of exercise, where one MET hour equals a little less than a mile of brisk walking or about two-thirds of a mile of running.
However, when the runners and walkers were looked at separately, there was significantly less mortality in those who ran than walked. The runners' risk for breast cancer mortality decreased over 40% per MET hour per day. Runners that averaged over 2 and a quarter miles per day were at 95% lower risk for breast cancer mortality than those that did not meet the current exercise recommendations. In contrast, the walkers' risk for breast cancer mortality decreased a non-significant 5% per MET hour per day.
Williams cautions, however, that this study doesn't disprove the benefits of walking because the number of subjects was small compared to previous research showing a benefit. However, he does believe that the research shows that exceeding the current exercise recommendations is probably better than simply meeting them, and that running may be better than walking.
"If I were a breast cancer survivor, I would certainly consider running or some other vigorous exercise over walking, and I wouldn't just be doing the minimum, with the consequences and potential benefit being so great," he adds
Previous research from the national study showed that running was more effective than walking for weight loss. For many health benefits, however, running and walking appear to give the same benefits for the same amount of energy expenditure. These include lower risk for coronary heart disease, diabetes, hip replacements, as well as brain cancer. Running and walking also seem to be equally beneficial in the primary prevention of breast cancer.
The National Runners' and Walkers' Health Studies were supported by a grant from the National Heart, Lung, and Blood Institute of the National Institutes of Health.
The IJC study is available here: http://onlinelibrary.wiley.com/doi/10.1002/ijc.28740/abstract
Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit http://www.lbl.gov.
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