Meredith Griffiths reported this story on Tuesday, January 12, 2010 08:26:00

TONY EASTLEY: Television viewing has often been accused of rotting the human brain, but it seems the real risk may be that it's doing some damage to the rest of your body.



Australian scientists have published research showing a link which suggests that the more people watch TV, the sooner they die.



The report says that every hour spent watching television increased people's risk of premature death.



Meredith Griffiths reports.



MEREDITH GRIFFITHS: Channel surfers are being warned that all the time they spend in front of the box, may be harmful to their health.



DAVID DUNSTAN: What this study provides is the first compelling evidence linking television viewing to an increased risk of early death.



MEREDITH GRIFFITHS: Professor David Dunstan works for the Baker IDI Heart and Diabetes Institute in Melbourne.



He and his team followed more than 8,000 Australian adults for six years. The ones who watched the most TV died younger.



DAVID DUNSTAN: People who watch four or more hours of television a day have a 46 per cent higher risk of death from all causes and an 80 per cent increased risk of death from cardiovascular disease.



MEREDITH GRIFFITHS: Professor Dunstan says the increased risk of premature death was independent of other risk factors like smoking, blood pressure, cholesterol, diet or exercise.



He says that that shows that too much sitting is bad for our health.



DAVID DUNSTAN: Essentially prolonged sitting, because that's the default position. And from that there's an absence of muscle movement. We know from extensive evidence that muscle contractions are so important for many of the body's regulatory processes, such as breaking down and using glucose.



So that loss of muscle movement for prolonged periods may result in a disruption to the body's regulatory processes.



MEREDITH GRIFFITHS: The report stresses that sitting too much is different from not exercising enough



DAVID DUNSTAN: The risks associated with prolonged sitting are also not necessarily offset by doing more exercise, because in this study, even people whom were exercising, if they also watched high amounts of television, they had an increase risk of premature death.



MEREDITH GRIFFITHS: So is TV just a bit of a scapegoat here? Couldn't part of the problem be the jobs we work these days? Lots of people are very sedentary in the office?



DAVID DUNSTAN: That is a very good point. We are actually starting to explore this and we have some preliminary evidence that indicates that nearly three-quarters of working hours in office-based employees is spent sedentary.



MEREDITH GRIFFITHS: Trevor Shilton from the Heart Foundation says this is a vitally important new field of study.



TREVOR SHILTON: In just a couple of generations we've gone from being a very active people to people who sit around for most of the day. I can foresee a time where we will have, in addition to our guidelines, a defined 30 minutes of physical activity a day.



Also guidelines about moving more and standing more throughout the day, and about sitting less, standing up every 20 minutes, going for a walk at work, having rules around television and computer times for our kids.



MEREDITH GRIFFITHS: The study is published in the journal Circulation today.



TONY EASTLEY: AM's radio reporter Meredith Griffiths.