Still Sitting?


There is compelling evidence that we sit too much – the negative health effects are real and measurable. It’s worse for the otherwise-inactive but even effects those who exercise!

“Sitting is the new smoking” has become quite a popular phrase in recent years. The notion is that sitting is a significant and independent health risk factor linked to mortality, obesity, cardiovascular health, diabetes, some cancers (colon, ovarian, endometrial), and poor mental health. The initial evidence for this claim seemed quite compelling3 5 6 12 and several lay-press as well as advisory-authority publications have been advising that we need to sit less, even if we are otherwise active. Is this sound advice or just a fad? Has more recent research confirmed the initial findings?

The science

Some 1000 published studies have looked at the issue, with 144 being of reasonable quality and 27 of high quality, by peer-review standards7. There is an association between prolonged sitting and poor health outcomes although there are complexities (and some conflicting findings) for example:

  • The findings vary slightly in different age groups7.
  • The type of sitting or sedentary behaviour influences the health-impact: TV watching is especially negative1.
  • There are associated risks with certain types of sitting e.g. TV watching includes exposure to unhealthy food advertising and snack-eating as well as being associated with psychosocial problems and lower socio-economic status8. These associated risks are difficult if not impossible to exclude or control-for in research.
  • The link to cancers (colon, endometrial, ovarian) is present but not strong7.
  • Some but not all studies have found that when BMI is controlled-for as a variable, the association with metabolic risk (diabetes) falls away8.
  • There is not yet consensus on the precise amount of sitting that should be encouraged or aimed for or set as a limit1.
  • Prolonged sitting is worst for those who are inactive (do not exercise) but several studies have also shown that prolonged sitting is associated with poor health outcomes even for those who are active (exercise)4.

In summary, the body of research is extensive and the results are convincing, even though more research is needed in several areas before full consensus is reached (it is worth noting that this is really the nature of all issues that science and rigorous research explore – the truth evolves over time as we learn).

The recommendations

World authorities have published a variety of recommendations and these continue to evolve over time. A reasonable and practical distillation of these, for adults, is that we should 1 9 10:

  1. Be active (non-sweaty or “incidental” activity such as walking) for 30 minutes each day or on most days.
  2. Exercise vigorously (sweaty exertion involving being short of breath) for 150 minutes each week.
  3. Minimise the amount of time spent sitting.
  4. Always seek medical advice before starting any exercise regimen.

Item 3 is a fairly new addition to the recommendations, and may be the most difficult one to achieve for many office workers who sit as they work. Most authorities do not currently set a specific target although research suggests that sitting for more than 4-5 hours a day is unhealthy1.

How to sit less

There are ways to reduce sitting-time, including:

  • Less TV – television consumes huge amounts of time that could often be spent more constructively. That the associated sitting adds health risk is an additional reason to curtail this habit.
  • Exercise equipment in the TV room – this seemingly “odd” idea really works for many people. Integrating activity into social and family and TV time can really make a difference.
  • Stand-up desks – they can be expensive and they take some getting-used-to, but standing desks are becoming more popular for good reason11.
  • Stand-up meetings – less sitting, more focus, better health, and nobody falls asleep!
  • Break it up – try not to sit for more than 30-45 minutes at a time. A short break or a quick walk will help.

It does seem clear that sitting is unhealthy. More specifically prolonged sitting (probably anything more than 4-5 hours a day), especially while watching TV, and especially (but not only) if you do not exercise. So, please, stand up!