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 It’s well known that too much sitting time is bad for our health.
“What we didn’t know was whether the sitting time and health
relationship was because people were also exercising poorly,” said
senior author Dr. David Alter of the Toronto Rehabilitation
Institute-University Health Network and Institute for Clinical
Evaluative Sciences, in a phone interview.
It turns out, he and his colleagues say, that sedentary time and
exercise time are two distinct factors when it comes to health
outcomes.
“Another way of saying it is just because one does their 30 to 60
minutes of exercise per day doesn’t ensure their health,” Alter
said. “These are two distinct factors, we need both, we need
exercise and need to be sitting less.”
The researchers analyzed 47 studies that tracked groups of people as
they reported roughly how much time they spent sitting around and
not expending much energy, as well as how often they exercised.
People who were the most sedentary were more likely to be diagnosed
with type 2 diabetes, breast, colon, ovarian and other cancers, and
cardiovascular disease than people who spent less time sitting.
They were also 24 percent more likely to die during the studies than
those who spent the least time sitting.
The pattern tended to be more pronounced for people who also
reported less time exercising, the authors reported in the Annals of
Internal Medicine. But regardless of physical activity level,
prolonged sedentary time was independently associated with bad
health outcomes.
The studies “all seemed to show a similar result,” Alter said.
“There is a strong and consistent link between sitting time and a
host of diseases.”
Strategies for encouraging people to sit less are different than
those used to promote exercise, he said.
“There are very simple things we can do, every half an hour get up
for two to three minutes,” he said. “You do that and that’s already
nearly an hour less sitting per day.”
Standing burns twice as many calories as sitting, he noted. People
can also stand during commercial breaks while watching TV or during
the last 15 minutes of a sporting event, he said.
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These strategies don’t replace daily exercise, Alter stressed.
None of the studies in the review were randomized controlled trials,
so researchers can’t yet say that sitting directly causes disease,
Alter said.
There will need to be considerably more research done to fill in
those gaps and help develop guidelines for sedentary behavior, like
there are for physical activity, Neville Owen, program head of
Behavioral & Generational Change at Baker IDI Heart and Diabetes
Institute in Melbourne, Australia, wrote in an editorial published
with the study.
Even among adults who meet the public health guideline – that is,
they walk at least 30 min a day – “those who sit for prolonged
periods have elevated health risk biomarkers,” Owen told Reuters
Health by email. “However, there is insufficient evidence yet to
know whether very highly active people who sit for prolonged periods
are also at risk.”
Regardless, sitting time was most important for nonexercisers, Alter
said.
“Those that do not exercise and who sit a lot, the health hazards
are accelerated quite markedly,” Alter said.
“If there is a priority population that I tune myself into, it’s the
nonexercisers high-sitting-time people.”
SOURCE: http://bit.ly/1i46lF7
Annals of Internal Medicine, January 19, 2015.
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