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Lack of exercise not behind rise in teen obesity -
study
Reported November 11, 2009
NEW YORK (Reuters Life!) - Most American teenagers are not as active
as they should be but a lack of exercise does not seem to be to blame for
the rising rates of teen obesity, according to a U.S. study.
Researchers, using government survey data from 1991 and 2007, found the
amount of physical activity among U.S. teens has not in fact changed
significantly over the past two decades while the population, including
children, has got heavier.
Researcher Youfa Wang, of Johns Hopkins University in Baltimore, said it
came as a surprise to find that a lack of exercise was not to blame for the
rise in obesity with nearly one-third of U.S. children and teens now
overweight or obese.
"Although only one third of U.S. adolescents met the recommended levels of
physical activity, there is no clear evidence they had become less active
over the past decade while the prevalence of obesity continued to rise,"
said Wang.
He said there was no evidence that teens' exercise levels had changed
appreciably at any time during the study period -- even though those years
saw an increase in teen obesity.
For the study published in the journal Obesity Reviews, Wang and colleagues
used data from an annual government survey that tracks the health and
lifestyle of U.S. high school students.
Overall they found only 35 percent of teenagers surveyed in 2007 met the
current recommendations for physical activity -- performing activities that
gets the heart rate up at least one hour per day, five or more days out of
the week.
But there was no evidence that teenagers' exercise habits shifted
significantly during the study period.
In 1993, for example, 66 percent of teens got enough short bursts of
vigorous exercise -- 20 minutes of running, biking or other heart-pumping
activity at least three days per week. That figure was 64 percent in 2005.
When it came to moderate exercise which should, according to guidelines, be
performed at least 30 minutes per day, on five or more days per week, only
27 percent met that goal in 1999.
That figure was unchanged in 2005.
On the other hand, there were some encouraging trends, according to Wang's
team. One was the recent increase in time spent in school physical education
classes.
In 2007, 30 percent of high schoolers were taking a daily physical education
class compared to 25 percent in 1995.
The researchers also found a decline in teenagers' TV time. In 1999, 43
percent of students spent three or more hours watching TV on school days but
this figure dipped to 35 percent in 2007.
Wang said these findings suggest that waning exercise levels are "not likely
the major explanation of the recent increase in obesity among U.S.
adolescents."
He said other factors, like unhealthy diets, may be the driving force.
However, the researchers added that this does not mean it is fine for
teenagers to be sedentary. Children and teens still need to develop regular
exercise habits for the sake of their overall health, according to the
researchers.
"Our study suggests that more vigorous efforts are needed to help young
Americans engage in adequate regular physical activity and reduce sedentary
behaviors, which will help promote good health," they said.
Source : Thomson Reuters |
