It’s possible to do regular exercise and still be a couch potato. And that inactivity can increase your cancer risk, said Charles E. Matthews, Ph.D., at today’s AICR conference session on Sedentary Behavior and Physical Activity. Matthews and other researchers are finding that sitting (being sedentary) too much is a separate health risk that needs to be studied separately from the health-protective effects of exercising.
“You can exercise 30 minutes a day, but if you sit the rest of the time your overall activity level is not that high,” he says. And it’s the total time you spending sitting that may be associated with cancer, according to Dr. Matthews (right), Physical Activity Epidemiologist and Investigator in the National Cancer Institute’s Division of Cancer Epidemiology and Genetics in Bethesda, Maryland.
Many adults spend 70 percent or more of their waking hours sitting — at desk jobs, in front of television and computer screens and in the car. On top of this inactivity, eating too much high-calorie convenience food has led to the obesity epidemic in this country, he says.
Too much sitting may be associated with an increased risk of cancer in several ways, according to Dr. Matthews and Neville Owen, PhD, a prominent inactivity researcher at Baker IDI Hart and Diabetes Institute in Australia. When a person sits too much, the mitochondria in our muscle cells don’t do their jobs, and as a result our energy metabolism it lower, increasing risk for weight gain.