Exercise and Cancer Prevention
by Trudy Harris
As an exercise professional, I am often asked if exercise can help protect against cancer. We know exercise is good for the heart and cardiovascular system, but can it reduce the risk of developing cancer? The answer is yes. In fact, one study estimates 90,000 cancer deaths a year are linked to obesity. A well-balanced exercise program is the most effective way to avoid excess pounds and maintain a lifelong healthy weight.
Breast cancer survivors who exercised the equivalent of walking 3-5 hours a week reduced their risk for recurrence by 50%. A study of women with BRCA mutations showed those who were active in sports, dance, or casual exercise during their teenage years had a delay in the onset of breast cancer later in life. BRCA carriers of normal weight (rather than overweight) at menarche and lighter weight at age 21 had a similar delay.
Women over age 25 tend to add a few pounds each year, even if they are not eating more. Many factors contribute to this increased weight, including a reduced activity level and loss of muscle. With less muscle, the metabolism, or rate of burning calories, slows. Cardiovascular exercise such as walking, biking or aerobics, is necessary for good health, but it burns fewer calories than people think. A pound is equivalent to 3,500 calories. Walking at a pace of 20 minutes per mile results in a loss of 300 calories after 69 minutes. At 15 minutes per mile, the same 300 calories are burned after 52 minutes. Since most people spend fewer than 30 minutes walking only a couple of times a week, the resulting weight loss is less than expected.
Resistance training—working out with weights, rubber bands, or anything that offers resistance, is the most efficient way to boost your metabolism and burn more calories. As your muscle mass increases, you burn more calories throughout the day, and even at night while you’re sleeping! A weight-resistance program plus cardiovascular exercise helps stabilize weight as you age.* It improves strength and balance, as well as the blood lipid profile (such as cholesterol level). Bones become stronger, blood circulation increases, and fat is burned more effectively. Even the immune system is stimulated. Exercise helps to prevent heart disease, stroke, diabetes, obesity, and several kinds of cancer. Yes! The prescription is exercise.
* Always discuss any new exercise program with your physician, especially after surgery or if you are at risk for lymphedema.
Trudy Harris is a Certified Clinical Exercise Specialist and Lifestyle & Weight Management Consultant.
Editor’s Note: A recent study of 1,073 women from five countries suggests losing as few as 10 pounds between ages 18 and 30 may dramatically reduce the risk for breast cancer in those who have a BRCA1 mutation. Study results published in the journal Breast Cancer Research.
E Calle, C Rodriguez, K Walker-Thurmond, M Thun. Overweight, obesity, and mortality from cancer in a prospectively studied cohort of U.S. adults. New England Journal of Medicine, April 2003; vol. 348, no. 17: p. 1625-1638.
M Holmes, W Chen, D Feskanich, C Kroenke, G Colditz. Physical activity and survival after breast cancer diagnosis. Journal of the American Medical Association, May 2005; vol. 293, no. 20: p. 2479-2486.
M King, J Marks, J Mandell. Breast and ovarian cancer risks due to inherited mutations in BRCA1 and BRCA2. The New York Breast Cancer Study Group. Science, October 2003; vol. 24: p. 643-6.
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