Lack of exercise not behind rise in teen obesity: study
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. Continued...