SECOND OPINION | The science of sitting

Hello and happy Saturday! Here's our roundup of the week's interesting and eclectic news in health and medical science.

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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 beganless 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.

Modern sedentary behaviour scientists have come at it from another angle, askingwhether the conductors were behaving the way humans are supposed to, by moving around, while the driverswereactually hurting theirhealth by sitting so much.

"We know there is a lot of associational evidence," said Tremblay,founder of theSedentary 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.

• How to fight the bad health effects of sitting all day at work

"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 dictionarywill 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, chairor a parent's hand; standing with the aid of crutches ora cane.

Huntingbats for new viruses

Meet Simon Anthony, virus hunter. He and his team are capturing bats and tracking coronaviruses in an effort to predict future SARS-like pandemics before they happen.

They travelled to 20 hotspots in Africa, Asia and South and Central America, where they caught and releasedthousands of bats, rodents and monkeys, and sent saliva and other samples off for virus testing.

"Our main goal was to find viruses that we didn't know about," Anthony told CBC Health.

The research is challenging some major assumptions about our ability to predict new pathogens that could trigger pandemic disease.

"I think one of the reasons people have not put much effort into trying to predict emergenceis that people think it's a very random eventand therefore impossible to predict," Anthony said. "The other is that people think there is an inexhaustible diversity of virus out there. I think that might not be true."

His group found 100 new viruses, and calculated that bats could be harbouring around 3,200 unidentified coronaviruses. He admits that's a big number, but insists it would be possible to catalogue them and determine whether they pose a threat to human health.

• 'Hairy-legged' vampire bats develop taste for human blood

"We don't know whether we'll ever be able to reliably predict things ahead of time, but at the very least we think we will be able to make ourresponse to outbreaks a lot faster simply by learning more about these viruses in wildlife," said Anthony, an assistant professor at New York's Columbia University.

For example, scientists would be able to react quickertoan outbreak if theyknow what viruses are prevalent in the local bats.

"We can implement some kind of intervention strategy that tries to block transmission from bats into people," Anthony said.

"It's all related to this idea of pandemic prevention and how can we get ahead of the curve. Making vaccines, building public health infrastructure, training people in how to respond to outbreaks that's critically important, but all that is still responding to outbreaks when they occur."

Anthony's program is part of a global virus surveillance project called PREDICT, funded by the United States Agency for International Development. (USAID).

His research has confirmed that bats are a major reservoir for coronaviruses, which cause some of the most dangerous human infections,likeSARS, whichkilled 774 people including 44 Canadians in a 2003 outbreak, and MERS, which is responsible for more than 700 deaths so far in an ongoing outbreak.