If ever you needed a shock to the system to make you get off your
backside and into a pair of trainers, this is it: Lack of physical activity kills
roughly as many people as smoking.
That is the shocking message from a series of papers published this week on the
health impact of inactivity.
The papers, published in The
Lancet suggest that more than 5.3 million deaths would be avoided
each year if all inactive people exercised, about the same toll as the
5 million deaths annually from smoking.
The deaths could have been
avoided if people reached a weekly target of150 minutes
or more of moderate exercise, such as brisk walking.
"We tried to estimate how
many deaths would be avoided if all the inactive people in the world became
active," says I-Min Lee at Harvard Medical School, head of the team that
published one of the papers.
Lee analysed data from 2008 on
deaths from four major illnesses that are already linked with lack of exercise
– coronary heart disease, type 2 diabetes, bowel cancer and breast cancer. Her
team combined data on the deaths with information on levels of exercise in each
country.
From this they calculated that if
everyone reached their weekly exercise targets, about 6 per cent of those
who died globally from heart attacks would have survived, as would 7 per
cent of those who died of type 2 diabetes, and 10 per cent of those who
died from breast or colon cancer.
Exercise pandemic
Harold Kohl of the University of
Texas Health Sciences Center in Houston, says the figures mean that inactivity
has created a modern-day "pandemic", brought on by mechanisation of
everyday jobs and domestic life, the ease of transport and the prevalence of
sedentary leisure pursuits, such as computer games and watching television.
"As populations have shifted
towards industrialisation, mechanisation and dependency on cars, we've
engineered opportunities for physical activity out of our lives, and are now
killing ourselves as a result," says Kohl, lead author of another article in The Lancet, which argues for global action
to reverse the situation.
In another paper, Pedro Hallal of the Federal University of Pelotas
in Brazil found that globally, 42 per cent of adults spend more than four
hours a day sitting, and two-thirds of adolescents spend two hours watching
television without a break each day.
Hallal says that the
situation shouldn't
be blamed on people having a lack of motivation, but rather on the creation
of environments in which it is impossible or inconvenient to move around and
exercise, walk or cycle.
Forced to walk
More than 100 cities in
South America have had some success combating this problem with schemes that
periodically close large roads to traffic. Called the Ciclovía, the movement
began 30 years ago in Bogotá, Colombia. "On 72 days of the year, 100
kilometres of city streets are closed to traffic," says Gregory Heath of
the University of Tennessee in Chattanooga, who has assessed the interventions around the world that worked best
to help people resume physical activity.
Heath says that at least a
million people take advantage of the Ciclovía in Bogotá alone, keeping visitors
active for an average of 140 to 180 minutes a week, and enabling about
14 per of the country's population to meet their weekly exercise targets.
Heath's study also revealed that
pedometers, which measure the number of steps a person takes daily, are highly
effective tools in motivating people to walk and exercise more. "They give
feedback, so people can see how much they've done, and set targets," he
says.
Olympic let-down
Unfortunately, even though the
Olympics are just around the corner, they're unlikely to inspire people to
exercise more.
"Olympic sports are an
elite, celebrity thing, connected to national pride, but not to physical
activity in everyday life," says Adrian Bauman of the University of Sydney
in Australia, and author of a paper exploring what makes some people exercise but not others. His research has
also shown that the Sydney Olympics in 2000 had
no impact on physical activity levels in Australia. "Elite sports
are not the way to slow the physical inactivity pandemic," he says.
One answer, Bauman says, is for
schools to focus less on producing prizewinning athletes and more on priming
all pupils to pursue physical activities that they can enjoy for the rest of
their lives.
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