A new study from the US Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and reported in the International Journal of Cancer finds breast cancer survivors who meet the exercise regimen recommendations of 2.5 hours of moderate intensity physical activity per week, sufficiently lower their risk of mortality.
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.
At least 31 of the 714 walkers and 13 of the 272 runners died from breast cancer over nine years.
When analyzed together, their risk for breast cancer mortality decreased an average of 24 percent 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-third 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 percent per MET hour per day. Runners that averaged over two and a quarter miles per day were at 95 percent 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 five percent per MET hour per day.
Williams cautions, however, that this study does not 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 will be 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 said.
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.