Reducing the time you spend sitting on your tush may also reduce your risk of death, a new study suggests. Though many earlier studies have looked at the connection between sitting and increased risk for ailments like type 2 diabetes, obesity, and heart disease, this is among the first to look at chair-time and mortality from any cause.
For women who sat for more than six hours per day, the risk of death from any cause was 37% greater than for women who spent less than three hours per day; and for men, this number was slightly lower, at 17%.
The new study used data from the American Cancer Society, which included surveys from over 123,000 people. The questionnaires included information about their lifestyles (jobs, smoking, weight, etc.) and health issues, if applicable, their cause of death. Participants were followed for 14 years.
The researchers, led by Alpa V. Patel, used the following question to determine how much time respondents spent sitting: "During the past year, on an average day (not counting time spent at your job), how many hours per day did you spend sitting (watching television, reading, etc.)?" Note that the researchers were only interested in sitting time outside of one's job.
The amount of exercise that people got did tend to counteract this link, but not completely – in other words, even when exercise was factored in, there was still a connection between sitting and increased death risk. But, not surprisingly, people who spent more than six hours a day sitting and who reported very little exercise were at the greatest risk of dying: for women it was 94% higher and for men it was 48% higher than their counterparts who sat less and exercised more.
The authors write that it's likely that sitting leads some harmful metabolic changes – like higher LDL ("bad") cholesterol, blood pressure, blood fats, glucose, and the appetite hormone leptin. And these changes are strong markers for obesity, heart disease, and other disorders, which could be behind the increased risk of death found for people who sit the most.
While researchers try to get to the "bottom" of this connection, one thing is clear: it can't hurt to get off the chair and add a little bit of exercise to your life – and possibly years to your lifespan.
Alpa V. Patel is a researcher with the American Cancer Society. The study was published in the July 22, 2010 online issue of the American Journal of Epidemiology.