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 The study included middle-aged and older adults who
had knee osteoarthritis or were at high risk of developing the
condition. It focused specifically on low-intensity exercise, like
strolling through a shopping mall or walking around the living room
during television commercials.
“This study shows that even light movement is beneficial,” lead
author Dorothy Dunlop told Reuters Health.
“We’re asking the couch potato to get off the couch for two hours a
day,” said Dunlop, from the Northwestern University Feinberg School
of Medicine in Chicago. “You can get up when the commercials come
on. You can walk around your block.”
Although public health officials and doctors sing the praises of
moderate-intensity and vigorous exercise, the benefits of
low-intensity activity remain unclear, the authors write in the
British medical journal BMJ.
The new study suggests that any movement has the potential to
forestall illness and disability, they add. However, it does not
prove that engaging in light activities was the reason certain
people maintained their health.
 Dunlop and her team studied 1,680 adults between 49 and 83 years old
who were living independently in one of four U.S. cities and did not
have a disability. All of them had knee osteoarthritis or risk
factors for the condition, which occurs when the protective
cartilage around the joint wears down over time.
At the beginning of the study, participants wore accelerometers on
their hip to measure their physical activity levels during waking
hours for seven consecutive days.
Two years later, 149 of those studied had become disabled and could
no longer perform basic activities on their own.
The more time participants spent stationary, the more likely they
were to develop problems getting around.
As expected, both moderate and vigorous exercise were linked to
long-term benefits. But even after the researchers accounted for
time spent on those higher-intensity activities, light movement was
still associated with a lower risk of disability.
Four or more hours a day of light activity was tied to a 30 percent
lower risk of disability, Dunlop said.
What’s more, when the researchers included people who already had
disabilities at the start of the study, they found those who engaged
in light activity were less likely to see their condition worsen.
“Even among people who cannot do very much moderate activity, there
was a strong benefit to participating in light activity to reduce
the risk of developing disability as well as disability
progression,” Dunlop said.
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“We hope this will provide an additional route to better health and
will add to the advice physicians give their patients,” she said.
“It may be a new route for interventions for people who have health
limitations.”
U.S. federal guidelines issued in 2008 call for adults to get at
least 150 minutes a week of moderate exercise. They stress the
health benefits of all physical activity but say nothing
specifically about light-intensity exercise.
Exercise scientist Todd Manini told Reuters Health he has no doubt
about the benefits of moderate exercise. But Manini, from the
University of Florida College of Medicine in Gainesville, said he
remains unconvinced about the benefits of low-intensity movement.
Manini studies the health advantages of exercise and sits on a
committee scheduled to make recommendations for new federal exercise
guidelines in 2018. He was not involved in the new research.
One limitation of the study is that it cannot determine cause and
effect, Manini said. He wondered, for example, if the people who
performed more low-intensity activities might have been in better
shape to begin with.
He also questioned the range that researchers used to measure
low-intensity exercise and whether it could have been so broad that
it encompassed moderate exercise as well.
Nevertheless, he praised the study for contributing to a growing
body of literature about light-intensity exercise.
“I would love to tell people if you do your light activity, you’re
going to get all the benefit,” Manini said. “But it could be a
dangerous place to go.”
He fears that expanding federal exercise guidelines to recommend
low-intensity activities might provide excuses for people who could
exercise more vigorously but would instead move just a little and
mostly remain chained to their couches.
But, he said, “You just can’t go wrong with the recommendation of,
‘Just keep moving.’”
SOURCE: http://bit.ly/1iz7IqG BMJ, online April 29, 2014.
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