The researchers examined data collected for the National Health and Nutrition Examination Survey in order to determine how much time US adults spent sitting down and watching TV each day. In addition, they analyzed five published studies on sitting time and deaths from all causes. Combined, the studies involved nearly 167,000 adults.
The research team discovered that individuals could live an additional two years if they decreased the amount of time they spent sitting to under three hours a day. In addition, they discovered that reducing the amount of time spent watching TV to under 2 hours each day would boost life expectancy by 1.38 years.
The researchers emphasize that their study assumes a causal association rather than proving that there is one. However, they note that earlier studies have connected extended periods spent sitting down and/or watching TV to poor health and ailments such as diabetes and heart disease.
Furthermore, the research team states that results of this study do not mean that someone who leads a more sedentary lifestyle can expect to live two or 1.4 years less than someone who is more active.
The researchers explain that, "The results of this study indicate that extended sitting time and TV viewing may have the potential to reduce life expectancy in the USA. Given that the results from objective monitoring of sedentary time in NHAHES has indicated that adults spend an average of 55% of their day engaged in sedentary pursuits, a significant shift in behavior change at the population level is required to make demonstrable improvements in life expectancy."
The authors conclude that further studies are required to determine recommendations on safe levels of sedentary behavior.