Van der Ploeg et al 2012 published the latest volume of some well-known research- moving is good for you. Following 22 497 Australians for 14 years, the researchers found a correlation between hours spent sitting and all-causes mortality. Those who sat 4-8hrs/day had 1.02% increase, 8-11hrs/day 1.15% and more than 11hrs/day 1.40%. Clearly people, who sit in their homes, card and for the majority of their work-life are at higher risk of death. Keeping in mind this is a correlational study we must be cautious in drawing conclusions. We know exercise rocks but is simply sitting that hazardous?
Patel et al 2010 followed over 125,000 Americans for 14 years and found similar data- those who sat more than 6 hours a day had a 1.71% chance of increased all-causes mortality. Dunstan et al 2009 followed 58,000 for over 6 years and found that for hour every hour in front of a screen the daily hazard of death increased 1.11%.
So we may not be aware of the direct mechanism of action. We may in fact, be observing a secondary effect of exercise or some other primary effect- it is unknown. All we do know is people who spend a lot of time sitting generally die sooner than those who don’t.
Now, we know exercise affects heart rate, blood pressure, blood-chemistry profiles, hormones, brain function and tons of other factors which control our bodies. So how can we know? At this point, our best evidence is the fact that ‘all-cause’ mortality rises, not simply mortality from metabolic syndromes. If was merely from the purely exercise factors- other factors of death should be just as common and yet the exerciser is life likely to die of bacteria compared to the couch surfer.
So operating under this assumption, the old instructions come back- move more, sit less, walk 30min every day, etc. All those little things which seem to add up to half a percentage point of death. The earlier the proper habits are developed and reinforced, the sooner we’ll get a handle on our obesity, type 2 diabetes and heart disease rates.