Sitting Won't Kill You - If You Walk Enough

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If you've been scared by dire reports of "sitting is the new smoking," your head may spin with a study that disputes that conclusion. Researchers followed 5000 London office employees for 16 years and found no association of long periods of sitting with increased risks of mortality. 

The Whitehall II study data was analyzed by researchers from Exeter University and University College London. They were able to look at five different indicators of sitting time, as self-reported on yearly questionnaires.

  • Work sitting (including commuting)
  • TV viewing time
  • Non-TV leisure time sitting
  • Total leisure time sitting (TV and non-TV leisure sitting)
  • Total sitting time (total of the above)

The participants also reported their physical activity over the previous four weeks, including daily minutes of walking time and weekly moderate-to-vigorous physical activity (MVPA). Mortality risks were assigned based on standard measures and 450 deaths were noted over the study period.

Sitting Didn't Increase Mortality Risk

Will sitting kill you? Not according to the conclusions of this large study. There was no increase in the risk of death from any cause no matter how much or how little the subjects sat each day.

If you got the recommended amount of daily exercise (MPVA), your risks were the same whether or not you sat for long periods at work or at home. Sitting didn't increase the risks you'd expect for people of the same gender, age or BMI indicator of obesity.

Does More Walking and Exercise Prevent the Health Risks of Sitting?

The group of office workers studied differed from the general population of the United Kingdom in one significant way - their daily walking time (an average of 42 minutes) was twice as long. Working in London required a more active commute to and from work.

Previous studies have found active commuting to decrease mortality risks.

The study group also got more moderate-to-vigorous exercise than typical in the UK. The largest effects of long sitting time was seen in previous studies in those who got no physical activity. This may dispel the conclusions of studies that exercise had no protective effect if you sat for long periods.

Overall, the study participants burned more calories in walking and in exercise than typical. This difference in energy balance may have overcome the risks of sitting.

Does Breaking Up Periods of Sitting Decrease Risks?

Short walking breaks have been shown by other studies to reduce the risks of long periods of sitting. This study didn't differentiate between total sitting time and whether or not the participants took active breaks regularly. It's possible that these workers were more likely to break up long sitting times, but this was not analyzed in this study.

Standing still, compared with sitting, may not decrease the risks of being inactive.

Using a standing desk to prevent sitting would have shown as less time spent sitting in this study.

Increasingly, activity monitors, including the Apple Watch, have inactivity alerts and coach you to get up and move around for one or more minutes each hour.

Study Conclusion - Sitting May Not Kill You

The study found no increased risks from sitting at work or at home, comparing people of the same activity level, age, gender and body fat. Sitting, by itself, didn't appear to be a risk factor for increased mortality. This contradicts findings in some previous studies, and further research may bring new conclusions.

Should you just stop worrying and plop yourself onto the couch? Not unless you put in the same average walking time as the workers studied. With 42 dedicated walking minutes and more exercise than the average person, they were probably near a goal of 10,000 steps per day, despite long hours of sitting. How about you?

Source

Richard M. Pulsford, Emmanuel Stamatakis, Annie R. Britton, Eric J. Brunner and Melvyn Hillsdon. "Associations of sitting behaviours with all-cause mortality over a 16-year follow-up: the Whitehall II study" International Journal of Epidemiology Accepted August 27, 2015. doi: 10.1093/ije/dyv191

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