The study of more than 14,000 women found that those with moderate or high aerobic fitness levels were much less likely to die from breast cancer.
“Women in the study’s lowest fitness category were nearly three times more likely to die from breast cancer than women in the most fit group,” said Dr. Steve Blair, study author.
“We believe this is the first study to evaluate the association of objectively measured fitness and risk of dying from breast cancer,” he said. “The results suggest a stronger protective effect than has been seen in most studies on self-reported physical activity and breast cancer, probably because the objective laboratory test of fitness is more accurate than self-reports of activity.”
The researchers studied women from 20 to 83 years of age who had no previous history of breast cancer. The study participants received an initial medical examination that included a maximal exercise test on a treadmill, between 1973 and 2001, and were monitored for breast cancer mortality through 2003.
“The good news is that women who do at least 150 minutes of moderate-intensity activity, like walking, per week will escape the low fitness category,” he said. “Even better for some women, this activity can be accumulated in 10-minute bouts.”
This level of exercise meets the federal “Physical Activity Guidelines for Americans” recommendations, and can be easily achieved in 30 minutes of exercise five days/week.
To develop the highest fitness category in this study, Blair said, women should aim for the “high activity” level recommended by federal guidelines, which includes 300 minutes of moderate-intensity activity, such as walking, over the course of the week. This can be achieved through 150 minutes/week of more vigorous activity, such as jogging or taking an aerobics class.
“With more than 40,000 women dying each year from this disease, finding a strong association between fitness, which can be improved by the relatively inexpensive lifestyle intervention of regular physical activity, such as walking, is exciting,” Blair said.
In addition, the study found that women with high aerobic fitness had lower body mass index, better cholesterol levels, lower blood pressure, and fewer chronic conditions such as diabetes and cardiovascular disease.
“This study is more evidence that physical activity is critical to health across our lifespan,” Blair said.
1. A Prospective Study of Cardiorespiratory Fitness and Breast Cancer Mortality. Medicine & Science in Sports & Exercise:Volume 41(4)April 2009pp 742-748.