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    Defining sedentary behaviour 

    Is stationary behaviour the same as sedentary behaviour? Absolutely not, according to sitting scientists.  

    You can be stationary but not sedentary, because standing is active.

    It's all explained in a new dictionary written by scientists studying sedentary behaviour, a field of research that began less than 10 years ago with the question: What if sitting is dangerous?

    "In the history of our species, we've largely moved, and so the imposition in contemporary society is the actual sitting. That's the change," said Dr. Mark Tremblay, a pioneer researcher in the emerging field.

    Some of the first hard data on the benefits of physical fitness came from a 1953 study comparing drivers and conductors on London's double-decker buses. Epidemiologist Jeremy Morris discovered that the drivers who sat for most of the day had more heart attacks than the conductors who were actively climbing the stairs and punching tickets.

    The conclusion: exercise prevents disease.

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    A 1953 study comparing drivers and conductors on London's double-decker buses found that the drivers, who sat for most of the day, had more heart attacks than the conductors, who were actively climbing the stairs and punching tickets

    . (Dan Kitwood/Getty Images)

    Modern sedentary behaviour scientists have come at it from another angle, asking whether the conductors were behaving the way humans are supposed to, by moving around, while the drivers were actually hurting their health by sitting so much.

    "We know there is a lot of associational evidence," said Tremblay, founder of the Sedentary Behaviour Research Network (SBRN) and an obesity researcher at the Children's Hospital of Eastern Ontario (CHEO) in Ottawa.

    But so far, there is no causal link between sitting and disease. The experiments required to try and find it pose an ethical problem. 

    "We've attempted to try some randomized controlled trials, but we can’t get ethics approval because you can't impose sedentary behaviour on research volunteers," Tremblay told CBC Health. 

    So far, research has associated sitting with cardiometabolic disease and skeletal weakness, and there are some emerging associations with mental and emotional health.

    Tremblay says the new dictionary will help move the field forward. It was published last weekend, after more than a year of discussion involving 85 researchers from all over the world, and includes some of the following definitions:

  • Sitting: a position in which one's weight is supported by one's buttocks rather than one's feet, and in which one's back is upright.
  • Active sitting: Working on a seated assembly line; playing guitar while seated; using devices that engage one's feet/legs while seated; doing arm ergometry while in a wheelchair.
  • Passive lying : Lying on a couch, bed or floor while sedentary.
  • Active lying : Isometric plank hold (yoga position).
  • Passive standing: Standing in line.
  • Active standing: Standing on a ladder; standing while painting, washing dishes, working an assembly line; standing while juggling; standing while lifting weights.
  • Supported standing: Standing while holding a couch, chair or a parent's hand; standing with the aid of crutches or a cane.