Too Much Sitting After 60 May Lead to Disability
For each extra sedentary hour per day, researchers found a 50 percent increased risk
By Kathleen Doheny
WEDNESDAY, Feb. 19, 2014 (HealthDay News) -- Too much sitting has been linked to increased risk for health problems such as heart failure and earlier death. Now, a new study finds older adults who sit too much are more likely to be disabled -- regardless of their exercise habits.
"Sedentary behavior is its own separate risk factor [for disability]," said study researcher Dorothy Dunlop, a professor of medicine at the Northwestern University's Feinberg School of Medicine. She evaluated the exercise habits of more than 2,000 men and women, aged 60 and above, and their ability to perform normal everyday activities.
"Regardless of how much time they spent in moderate physical activity, the more time they spent being sedentary, the more likely they were to be disabled," Dunlop said.
However, another expert wonders if the relationship may occur in the opposite way -- that the more disabled people are, the more sedentary they are due to inability to exercise.
The study was supported in part by the U.S. National Institute for Arthritis and Musculoskeletal Diseases. It was published online Feb. 19 in the Journal of Physical Activity & Health.
Dunlop and her colleagues evaluated responses given to the U.S. National Health and Nutrition Examination Survey. The men and women answering the survey wore accelerometer devices to measure their activity on at least four different days between 2002 and 2005.
Few met the guidelines of getting moderate activity for 2.5 hours a week, Dunlop said. Only about 6 percent met that goal, and the other 94 percent did not, the study found.
On average, the men and women spent nine hours a day being sedentary during waking hours. About 4 percent reported being disabled. Disability was defined as having much difficulty (or inability) in performing activities of daily living, such as getting out of bed, dressing and walking.
For each additional daily hour of being sedentary, the odds of disability rose about 50 percent, Dunlop said. For instance, a woman aged 65 who was sedentary for 13 hours a day was 50 percent more likely to be disabled than a woman who was sedentary for 12 hours, she explained.
What is it about sitting? Dunlop can't say for sure, but said experts think that sitting for an extended period causes muscles to burn less fat and blood to flow more sluggishly. Idle muscles and sluggish blood flow can contribute to high blood pressure, heart disease, swollen ankles and diabetes.
Dunlop's study found a link, not a cause-and-effect relationship.
The connection may actually go the other way, said Andrea LaCroix, a professor of epidemiology in family and preventive medicine and director of the Women's Health Center of Excellence at the University of California, San Diego School of Medicine. She recently found a link in her own study between higher amounts of sedentary time and higher risk of death in older women.