Much research has shown a link between regular, moderately intense or vigorous exercise and a lower risk of breast cancer. While less intense exercise can benefit general health, this research suggests that lower-intensity exercise doesn't really lower breast cancer risk.
A study found that only vigorous exercise was linked to a lower risk of breast cancer in postmenopausal women, and only when that exercise was done from mid-life onward.
This research was done in a collaboration between the National Institutes of Health (NIH) and AARP. Nearly 120,000 postmenopausal women, all AARP members between the ages of 50 and 71, completed a comprehensive health survey that included questions about levels of regular exercise activity over their lifetimes. During a period of over 6.5 years after completing the survey, the heath status of these women was followed. Over 4,200 women developed breast cancer during this follow-up period. The researchers compared the exercise histories of the women who did and did not develop breast cancer.
- Women who reported more than 7 hours per week of high-intensity exercise activity during the 10 years prior to the survey were 16% less likely to be diagnosed with hormone-receptor-positive breast cancer, compared to women who reported lesser levels of exercise activity. Hormone-receptor-negative breast cancer was also less likely to be diagnosed, but the research team couldn't be sure that the difference seen with hormone-receptor-negative breast cancer wasn't just the result of chance.
- Regular exercise that was not high-intensity was not associated with a lower risk of postmenopausal breast cancer.
- Regular exercise at any level prior to age 40 was not associated with a lower risk of postmenopausal breast cancer.
- The reduced breast cancer risk seen with regular high-intensity exercise was not linked to weight; in other words, regular high-intensity exercise lowered postmenopausal breast cancer risk regardless of a woman's weight.
The researchers caution that the reliability of these results may have been influenced by at least two important factors. First, only a small portion of the 3.5 million women who were invited to participate in the survey chose to participate. It is possible that factors that influenced the decision to participate may have resulted in a study group that doesn't truly represent all women. Second, the exercise levels were based on self-reporting from memory and not based on direct observation of actual exercise levels over time. Self-reporting can result in over-estimating and under-estimating actual exercise activity at points in the past.
The following would be examples of vigorous exercise: running, fast jogging, scrubbing floors, and chopping wood. Examples of non-vigorous activities would be walking, washing clothes, and mowing the lawn.
Along with healthy diet and lifestyle choices, regular exercise is one of the best steps ALL WOMEN can take to help keep breast cancer risk as low as it can be. This and other studies suggest that the more intense the exercise, the more likely the reduction in breast cancer risk. Regular exercise also helps keep your general health the best that it can be. No matter how old you are, it's never too soon or too late to get moving.