This was a statistical work from data on 220,000 people in a large Australian longitudinal study, and it claims to show that sitting time correlates with increa

This was a statistical work from data on 220,000 people in a large Australian longitudinal study, and it claims to show that sitting time correlates with increased mortality independently of level of physical activity. Some thoughts: http://www.fightaging.org/archives/2012/04/sitting-time-correlating-with-mortality-independently-of-exercise.php http://www.fightaging.org/archives/2012/04/sitting-time-corr... This is not the first study to propose this correlation, of course. There are a range of others from past years. One has to wonder what the mechanism is here, however - my suspicion is that it actually does all come back down to the level of physical activity in the end. In these massive studies the level of exercise and activity is reported by the participants. A person who stands and works is going to be somewhat more active than a person who sits and works, even though that time may not be categorized as physical activity, or reported differently. Exercise is much like calorie restriction - the effects are so large in comparison to other factors we have easy access to that they are likely to creep into any study. You might look at a recent study on activity and Alzheimer's disease that was one of the few to use measuring devices rather than reports of activity. One point that emerges is that a fair degree of ongoing low level activity and exercise won't be classified as such by the participants of study without machine measurement. Housework, taking out the trash, the small increase in energy expenditure from standing while waiting versus sitting while waiting, that sort of thing repeated day in and day out. How much you are sitting really does sound a lot like a proxy for how much activity you are undertaking when you are doing things that most people don't really count as activity.