Sitting for long periods each day linked to increased mortality
Even people who exercise the recommended two-and-a-half hours per week likely face an increased risk of death if they sit a lot every day, according to a new study on sitting's health risks.
The study is not the first to link sedentary behavior and increased death risk, but it is one of the first to measure participants' activity levels using a device attached to their hips instead of relying on questionnaires to estimate activity.
It included about 8,000 participants who were 45 or older. Over a median follow-up period of four years, 340 participants died, according to the results. Those who sat or stood still for at least 12-and-a-half hours per day in bouts of 30 minutes or more had the highest risk of death, according to study results. Those who were less sedentary overall had a lower risk of death, even if they sometimes sat for hours at a time, the results showed.
Researchers from Columbia University Medical Center and Weill Cornell Medical Center led the study, which was published Monday by the Annals of Internal Medicine. Researchers measured activity and outcomes among people participating in a large ongoing stroke study called REGARDS, which includes black and white people from a range of geographical areas.
Dr. Indu Poornima, an Allegheny Health Network cardiologist who was not involved with the study, said the results strengthen evidence that should make doctors pay closer attention to the risks of sitting.
“I think it's worthwhile re-looking at those recommendations we make, and as physicians maybe we need to start asking that question of how much time do you spend sitting,” Poornima said.
The total number of sedentary hours is the biggest determinant of a person's risk, but breaking up bouts of sitting can help, the study found. Moving every 30 minutes appears to reduce risks most, but the study's authors acknowledge most working adults can't realistically move that often.
The science of sedentary behavior is more limited than the science of physical activity, said Bonny Rockette-Wagner, an assistant professor in the Department of Epidemiology at the University of Pittsburgh's Graduate School of Public Health.
So while the Centers for Disease Control and Prevention has been able to create weekly exercise guidelines for adults, older adults, pregnant women and children, recommendations for how much to limit sitting are not yet possible, Rockette-Wagner said.
Some researchers are homing in on a target of around six hours, she said, but more research is needed.
“The most important thing I would tell people is to try to reduce the total amount of time you spend sitting,” she said.
The new study helps advance the research, but still has some limitations, she said. The study measured participants' activity for only a week, estimating average times based on the measurements.
It didn't distinguish between sitting and standing still. Rockette-Wagner said standing seems to be better for back and neck posture but not necessarily to improve cardiovascular health or other physiological outcomes. Another recent study found little difference in the risks from sitting and standing .
Because it wasn't a randomized, controlled trial, the study could be affected by unknown variables, Poornima said.
“In a cohort study such as this, there are many other confounders that you really can't account for. We have no idea what dietary patterns these patients followed,” she said.
Rockette-Wagner said she tells her friends and family to find creative ways to get up and move around – whether it's pausing a TV show to get a little exercise or walking up a stairwell at work.
“It's about finding ways that work in your life, because there's no one suggestion for everybody,” she said.
Wes Venteicher is a Tribune-Review staff writer. Reach him at 412-380-5676, firstname.lastname@example.org or via Twitter @wesventeicher.