Americans may add as many as two years to the nation’s life expectancy if they can stand up more often and watch fewer hours of television, a study found.
While studies have shown that too much time sitting and watching TV are bad for a person’s health, today’s research in the journal BMJ Open is the first to show how reducing sedentary behaviors may increase life expectancy in the U.S., now about 78 years, said Peter Katzmarzyk, the lead author.
“It’s about the inactivity in your muscles,” Katzmarzyk, a professor of epidemiology at Pennington Biomedical Research Center in Baton Rouge, Louisiana, said yesterday in a telephone interview. “When you’re sitting your legs are completely inactive.
‘‘It’s not just about getting physical activity in your life. Just because you’re doing 30 minutes of physical activity, what about the other 23.5 hours,” he said. “Don’t just sit the rest of the day.”
For those who work in an office setting, standing during meetings, walking over to a colleague’s desk rather than sending an e-mail and getting up as often as possible are a few ways to keep the muscles in the body active, he said.
Reducing sitting time to fewer than three hours a day may add two years to U.S. life expectancy and cutting TV viewing time to fewer than two hours a day may extend life by about 1.4 years, according to the study, which analyzed previous research.
The researchers pooled data from five studies that involved almost 167,000 adults. They combined the data with figures from the National Health and Nutrition Examination Survey, which was used to determine how much time U.S. adults spent sitting and watching TV. Americans watch an average of five hours of TV a day, according to a June 2011 study in the Journal of the American Medical Association.
The analysis found that sitting less would reduce premature deaths by 27 percent in the U.S., while spending fewer hours in front of the TV may reduce it by 19 percent, Katzmarzyk said.
Previous research has shown that every two hours of television viewing raises the risk of Type 2 diabetes 20 percent, the risk of cardiovascular disease 15 percent and the risk of early death 13 percent.
While today’s study looked at the total U.S. population, individual actions such as weight, diet, health and whether someone smokes go together with other factors to determine a person’s life span, said Nancy Copperman, director of public health initiatives at North Shore-LIJ Health System in Great Neck, New York.
“I wouldn’t bet I would die two years earlier because I sat in the office all day,” Copperman, who wasn’t an author on the study, said yesterday in a telephone interview. She did agree that people who sit as part of their jobs “need to take an activity break where we actually get up and walk around.”
More studies are needed to determine how many hours of sitting are bad for people’s health and how to reduce sedentary behavior, Katzmarzyk said.