I’ve been reading a lot about the impact of various lifestyle factors on mortality risk (as I usually do), and I came across a very interesting meta-analysis on whether or not the health impact of sitting can be offset. As you’ve probably heard, a sedentary lifestyle (defined by >8 hours per day spent sitting) has been described as being as dangerous to your long term health as smoking! From what I’ve seen, even being physically active regularly does not completely offset this risk – until now! (That was a Dr Greger-ism).
A new study I came across in The Lancet gives us evidence that physical activity does in fact counter the dangerous effects of prolonged sitting. The paper was a meta-analysis (a big study which used the combined data of several smaller studies). The combined population of the 16 studies reviewed totaled over 1 million individuals and spanned a time period of up to 18 years, giving this review some serious weight. Here are the take home points:
- Exercise DID offset the mortality risks of sitting (approximately 1 hour of moderate exercise cancels the increased risk associated with 8 hours of sitting)
- The most active quartile of individuals (60-75 minutes of moderate exercise daily) had no increased mortality risk from daily sitting
- The least active quartile of individuals (5 minutes of moderate exercise daily) had an increased risk of mortality, even if they didn’t sit for long periods
This, to me, clearly shows that as bad for you as sitting is, exercise is still much better for you! So if your job requires long periods of daily sitting don’t feel hopeless – just be sure to get plenty of exercise in too!
Now, as an interesting further investigation, the researchers performed the exact same comparison with exercise, mortality risk and time spent watching television (instead of sitting). The population size that had TV watching data was much smaller, but the results were startling. Here’s what they found:
- Watching TV for 3+ hours a day increased mortality risk, regardless of activity level (except for the most active quartile)
- The most active quartile was protected from increased mortality of 3 hours of television per day, but still saw an increased risk from 5 or more hours of TV viewing per day.
This shows 1) That TV watching is significantly more dangerous to your health than just general time spent sitting, and 2) It is so dangerous that 3-5 hours of TV viewing per day will increase your risk of death, no matter how much you exercise!
In conclusion: Exercise a lot, sit as little as you can, and throw away your damn TV!
As an aside, this information is part of a larger philosophy I’m putting together on exercise and movement for general health and longevity. We are working on our second book (hooray!) and concepts and recommendations like the ones above will definitely be included throughout!
Ekelund, Ulf, et al. “Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women.” The Lancet 388.10051 (2016): 1302-1310.
