Although the research is preliminary, several studies
suggest people who spend most of their days sitting are more likely to be fat,
have a heart attack or even die as a result.
In an editorial published
this week in the British Journal of Sports Medicine, Elin Ekblom-Bak of the
Swedish School of Sport and Health Sciences suggested that authorities rethink
how they define physical activity to highlight the dangers of sitting. While
health officials have issued guidelines recommending minimum amounts of physical
activity, there is little or no advice suggesting people limit how much time
they spend sitting.
"After four hours of sitting, the body starts to
send harmful signals," Ekblom-Bak said. She explained that genes regulating the
amount of glucose and fat in the body start to shut down. Even for people who
exercise, spending long stretches of time sitting at a desk is still
harmful.
Tim Armstrong, a physical activity expert at the World Health
Organization, said people who exercise every day, but still spend a lot of time
sitting, might benefit more if that exercise were spread across the day, rather
than in a single event.
Aytekin Can, 31, works at a London financial
company and spends most of his days sitting in front of a computer. Can teaches
jiu jitsu, a Japanese martial art involving wrestling, several evenings a week,
and also partakes in Thai boxing. "I'm sure there are some detrimental effects
of staying still for too long, but I hope that being active when I can helps,"
he said. "I wouldn't want to think the sitting could be that
dangerous."
In a study published last year that tracked more than 17,000
Canadians for about 12 years, researchers found people who sat more had a higher
death risk, independently of whether or not they exercised.
"We don't
have enough evidence yet to say how much sitting is bad," said Peter Katzmarzyk
of the Pennington Biomedical Research Center in Baton Rouge, who led the
Canadian study. "But it seems the more you can get up and interrupt this
sedentary behaviour, the better."
Ekblom-Bak echoed this and encouraged
people to get up more. "People should keep exercising because that has a lot of
benefits. But when they're in the office, they should try to interrupt sitting
as often as possible," she said. "Don't just send your colleague an email. Walk
over and talk to him. Standing up."
The belief that sitting for too long
is bad for people's health is not new. In 2005 the Medical Research Institute of
New Zealand in Wellington studied 62 people who suffered from deep vein
thrombosis (DVT), including taxi drivers, IT workers and managers, and found 34
percent of the cases were a result of being seated for long periods at work.
However, a family history of DVT was also a significant factor in getting the
disease, the study said.
"Seated immobility as a result of either work
or travel accounted for nearly half the cases. Seated immobility at work may
represent an important independent risk factor," the 2005 study stated. It has
long been assumed that passengers on long haul flights were mainly at risk of
developingDVT, which is also known as "economy class syndrome".
Deep
vein thrombosis is a condition where blood clots form within a deep vein,
commonly in the thigh or calf. The clots can partially or completely block the
flow of blood, causing swelling, pain and hypertension. If the clot travels to
the lungs it can cause a pulmonary embolism, which is potentially fatal, and can
kill within hours. The condition is treatable with blood thinning
drugs.
The New Zealand study found that "seated immobility at work was
identified as a risk factor" if, in a four week period prior to the onset of
symptoms, a worker had been seated for three hours at a time without getting up
during an eight-hour shift. The study said that workers in an IT industry call
center were at risk if they remained seated for more than one hour at a time
without getting up over a period of up to 12 hours a day.
"Deskbound
people in front of a computer, like IT workers or call center workers, can be
seated for 12 to 14 hours a day, day after day," institute director Richard
Beasley said, "Many times they don't get up for three to four hours." This
resulted in more cases of DVT involving people seated for long periods at work,
according to Beasley.
Figures from a U.S. survey in 2003-2004 found
Americans spend more than half their time sitting, from working at their desks
to sitting in cars.
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