Exercise for Life
Women: You've heard about the many benefits of regular exercise. Now a recent study shows that women diagnosed with breast cancer who engage in regular physical activity have an increased rate of survival over those who don't exercise.
The study examined the physical activity of 2,987 female registered nurses who were diagnosed with stage I, II, or III breast cancer between 1984 and 1998. Physical activity was assessed using metabolic equivalent task (MET) hours. Three MET-hours equal walking at an average pace of 2 to 2.9 mph for one hour. Categories of MET-hours per week were classified as fewer than 3; 3 to 8.9; 9 to 14.9; 15 to 23.9; and 24 or more. Participants were asked about the amount of time they spent engaged and participated in physical activities in 1986. Physical activity was then assessed at intervals in 1988, 1992, 1994, 1996, 1998, and 2000.
Results: Compared with women who engaged in physical activity fewer than 3 MET-hours per week, the adjusted relative risk of death from breast cancer was 20 percent lower for 3 to 8.9 MET-hours per week of physical activity; 50 percent lower for 9 to 14.9 MET-hours per week; 44 percent lower for 15 to 23.9 MET-hours per week; and 40 percent lower for 24 MET-hours per week or more. The absolute unadjusted risk of death reduction was 6 percent at 10 years for women who engaged in 9 MET-hours per week or more, compared with women who engaged in fewer than 3 MET-hours per week.
The researchers concluded that "Women who engaged in an amount of physical activity equivalent to walking 1 or more hours per week had better survival compared with those who exercised less than that or not at all." Researchers also noted that maximal benefit occurred in women who walked 3 to 5 hours per week at an average pace of 2-2.9 miles per hour.
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Holmes MD, Chen WY, Feskanich D, et al. Physical activity and survival after breast cancer diagnosis. JAMA May 25, 2005;293(20):2479-2486.