An Australian study has found that watching just four hours of television a day can increase the risk of dying from heart disease by 80 percent.
Australian researchers from the Baker IDI Heart and Diabetes Institute tracked 8000 individuals for an average of six years and found that those who watched more than four hours of TV a day were 46 percent more likely to die of any cause and 80 percent more likely to die of cardiovascular disease than those who watched less than two hours a day.
Researchers also reported that the risk of premature death from any cause increased by 11 percent and for heart attack by 18 percent for each hour a day of inactivity spent in front of the TV.
And it's not just couch potatoes who are at risk. Even those who exercised regularly were at increased risk of dying prematurely the longer they spent being inactive.
The results are supported by other research which has shown that prolonged inactivity can affect the body's processing of fats and other substances that contribute to heart disease. These studies suggest the risks can be mitigated by avoiding extended periods of sitting.
"It's not the sweaty type of exercise we're losing," Dr David Dunstan, a researcher at Baker IDI Heart and Diabetes Institute said in a press statement.
"It's the incidental moving around, walking around, standing up and utilising muscles that [doesn't happen] when we're plunked on a couch in front of a television."
The report, published in the American Heart Association journal Circulation, focuses on watching TV as it's a popular Australian leisure-time activity. However, Dr Dunstan says it's likely to apply to other sedentary activities such as sitting in front of a computer, reading a book or driving.
Participants in the study were an average of 50 years of age when they enrolled and after the six-year follow-up, 284 had died, including 87 from cardiovascular causes and 125 from cancer.
For tips on how to boost your incidental exercise without even noticing, read Shape Mate's tips or see their Incidental exercise fitness plan.