Breast cancer is the most common form of cancer among women, with roughly 237,000 cases diagnosed in the United States each year. Nearly one-fourth of women with breast cancer will die within 15 years of diagnosis. Findings from a 2014 study indicate that running reduces the risk of death from breast cancer.

Most public health organizations recommend that adults of all ages engage in at least 150 minutes of moderate-intensity exercise or at least 75 minutes of vigorous-intensity exercise each week, or an equivalent combination of both. Most adults fall far short of these recommendations, however.

Data from epidemiological, clinical, and mechanistic studies suggest that exercise reduces the risk of cancer-related death. However, scientists are unsure about how much or what type of exercise is best. Running and walking are both aerobic forms of exercise, but they differ in intensity, with running categorized as vigorous, and walking categorized as moderate. The authors of the study investigated whether running and walking differed in their effects on breast cancer-related death risk.

The authors drew on data collected in the National Runners' and Walkers' Health Study, a long-term assessment of the health benefits associated with running and walking. They compared death rates among 272 runners and 714 walkers who had previously been diagnosed with breast cancer, taking age, race, menopause, family history, breastfeeding and oral contraceptive use into account. They quantified the intensity of the women’s activity as metabolic equivalents, or METs, a measure of the rate of energy expended per unit of time.

Over a nine-year period, the risk of death from breast cancer was 49 percent lower among women who ran or walked 1.8 to 3.6 MET-hours per day and 68 percent lower for 3.6 MET-hours per day, when compared to less active women. Among runners only, the risk of death from breast cancer was 14 percent lower among women who ran 1.07 to 1.8 MET-hours per day, 87 percent lower for 1.8 to 3.6 MET-hours per day had a, and 95 percent lower for 3.6 hours or more per day, when compared to those who ran for less than 1.07 MET-hours per day.

The findings indicate that running promotes greater survival among women who have had breast cancer. The authors noted that the amount of exercise that provided the greatest protection exceeded current guidelines, suggesting that breast cancer survival could be increased by engaging in greater exercise doses than recommended. Other behaviors that may promote breast cancer survival include dietary modifications, especially time-restricted eating. Learn more about the effects of time-restricted eating on breast cancer survival in this clip featuring Dr. Ruth Patterson.

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