March 30 People who spent a lot of time sitting
at a desk or in front of a television were more likely to die
than those who were only sedentary a few hours a day, according
to an Australian study that looked at death rates during a
Researchers, whose results appeared in the Archives of
Internal Medicine, found that the link between too much time
sitting and shortened lives stuck even when they accounted for
how much moderate or vigorous exercise people got, as well as
their weight and other measures of health.
That suggests that shifting some time from sitting to light
physical activity, such as slow walking or active chores, might
have important long-term benefits, they added.
"When we give people messages about how much physical
activity they should be doing, we also need to talk to them
about reducing the amount of hours they spend sitting each day,"
said Hidde van der Ploeg, the new study's lead author from the
University of Sydney.
Of more than 200,000 adults age 45 and older, van der Ploeg
and her colleagues found that people who reported sitting for at
least 11 hours a day were 40 percent more likely to die during
the study than those who sat less than four hours daily.
That doesn't, however, prove that sitting itself cuts
people's lives short, she noted, adding that there could be
other unmeasured differences between people who spend a lot or a
little time sitting each day.
The team surveyed about 220,000 people from New South Wales,
Australia, between 2006 and 2008, including questions about
participants' general health and any medical conditions they
had, whether they smoked and how much time they spent both
exercising and sitting each day.
Then the research team tracked responders using Australian
mortality records for an average of almost three years, during
which 5,400 - between two and three percent - died.
They found that the extra risk tied to sitting held up
regardless of whether people were normal weight or overweight,
how much time they spent working out and whether they were
healthy or had pre-existing medical conditions.
Van der Ploeg said too much sitting may affect blood vessels
and metabolism by increasing fats in the blood and lowering
"good" cholesterol levels.
"When you are standing or walking, your leg muscles are
constantly working which helps to clear blood glucose and blood
fats from the blood stream," she said. "If you are sitting, this
is not happening because the muscles are not active."
The findings are consistent with other recent studies
suggesting health consequences from too much sitting, said Mark
Tremblay, an obesity and activity researcher at Children's
Hospital of Eastern Ontario in Canada.
"Sitting or reclining, especially in front of screens, is
bad for you regardless of your age," said Tremblay, who wasn't
involved in the study.
He added that even though people tend to think they're okay
as long as they work out a certain amount a day, that's not
necessarily the case.
"Getting your 30 minutes of physical activity five times a
week is not insurance against chronic disease.
Both he and Van der Ploeg said there were ways that even
people who have jobs involving a lot of desk work can train
themselves to regularly interrupt sedentary behavior, such as
standing up while on the phone or holding a stand-up meeting.
"Make sure the fax machine is four steps away from you, not
within reaching distance," Tremblay said.
"Drink enough water that you have to pee four times a day.
Stand up, stretch, walk around a little bit, say 'hi' to your
friend in the cubicle next door."
(Reporting from New York by Genevra Pittman at Reuters Health;
editing by Elaine Lies)