MONDAY, March 26 (HealthDay News) -- For better health, try
standing up more, a new study suggests. Those who spend 11 or more hours a
day sitting are 40 percent more likely to die over the next three years
regardless of how physically active they are otherwise, researchers
say.
Analyzing self-reported data from more than 222,000 people aged 45 and
older, Australian researchers found that mortality risks spike after 11
hours of total daily sitting but are still 15 percent higher for those
sitting between 8 and 11 hours compared to those sitting fewer than 4
hours per day.
"The evidence on the detrimental health effects of prolonged sitting
has been building over the last few years," said study author Hidde van
der Ploeg, a senior research fellow at the University of Sydney. "The
study stands out because of its large number of participants and the fact
that it was one of the first that was able to look at total sitting time.
Most of the evidence to date had been on the health risks of prolonged
television viewing."
The study is published in the March 26 issue of the Archives of
Internal Medicine.
Average adults spend 90 percent of their leisure time sitting down, van
der Ploeg said, and fewer than half meet World Health Organization
recommendations for 150 minutes of at least moderate-intensity physical
activity each week.
The data was collected as part of Australia's 45 and Up Study, a large,
ongoing study of healthy aging. Strikingly, the elevated risks for dying
from all causes remained even after taking into account participants'
physical activity, weight and health status.
Sixty-two percent of participants said they were overweight or obese (a
similar proportion to Americans), while nearly 87 percent said they were
in good to excellent health, and one-quarter said they spent at least 8
hours each day sitting.
Inactive participants who sat the most had double the risk of dying
within three years compared to active people who sat least, van der Ploeg
said, and among physically inactive adults, those who sat the most had
nearly one-third higher odds of dying than those who sat least.
Because many people must sit for long hours at their jobs, they should
make sure a greater portion of their leisure time is spent standing,
walking or engaging in other movement, said Dr. Suzanne Steinbaum,
director of Women and Heart Disease at Lenox Hill Hospital in New York
City and a spokesperson for the American Heart Association.
"Yes, you have to work, but when you go home it's so important you
don't go back to sitting in front of the computer or television,"
Steinbaum said. "After the 8-hour mark, the risks go up exponentially.
It's really about what you're doing in your leisure time and making the
decision to move."
Several workplaces in Australia are testing sit-stand work stations,
van der Ploeg said -- a generally well-received initiative that may be a
future option for other offices. "Try ways to break up your sitting and
add in more standing or walking where possible," she suggested.
While the study uncovered an association between total sitting hours
and death risk, it did not prove a cause-and-effect relationship.
The study was limited by the relatively short follow-up period of less
than three years, experts said, which may have obscured undiagnosed health
problems among participants that could have led to earlier death. Dr.
David Friedman, chief of heart failure services at North Shore Plainview
Hospital in Plainview, N.Y., said those who sit longer "tend to be sicker,
have obesity issues and cardiovascular problems. Perhaps they're less
ambulatory in the first place."
Van der Ploeg acknowledged these limitations and said more studies will
need to replicate the findings and focus more on sitting's influence on
developing conditions such as diabetes, cancer and heart disease.
"Studies that measure sitting time with activity monitors instead of
questionnaires will also help build the evidence base," she said. "All
these studies will further inform us of the exact relationship between
sitting and health conditions, which ultimately will result in public
health recommendations like we already have for physical activity."
More information
Read more about the World Health Organization's
physical activity recommendations.
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