One of the largest studies of its kind shows just how sluggish American children become once they hit the teen years: While 90 percent of 9-year-olds get a couple of hours of exercise most days, fewer than 3 percent of 15-year-olds do.
What's more, the study suggests that fewer than a third of teens that age get even the minimum recommended by the government – an hour of moderate-to-vigorous exercise, like cycling, brisk walking, swimming or jogging.
The sharp drop raises concerns about inactivity continuing into adulthood, which could endanger kids' health throughout their lives, the study authors said.
The new findings come just a week after an influential pediatricians group recommended that more children have their cholesterol checked and that some as young as 8 should be given cholesterol-lowering drugs. That advice was partly out of concern over future levels of heart disease and other ailments linked to rising rates of childhood obesity.
The latest study, appearing in today's Journal of the American Medical Association, tracked about 1,000 U.S. children at various ages, from 2000 until 2006.
Special gadgets were used to record their activity. Average levels of moderate-to-vigorous activity fell from three hours a day at age 9 to less than an hour at age 15.
The National Institute of Child Health and Human Development funded the research, calling it one of the largest, most comprehensive studies of its kind to date.
James Griffin, science officer for the study, said that as children mature, “You would expect somewhat of a decline (in activity), but nothing of this magnitude.”
He noted that the study coincided with the rise in popularity of video games, DVDs and Internet use – “all of the types of things that take children from outside and put them on a couch or in front of a computer.”
Mary Lee, 13, said the results ring true.
The Cleveland teen said she spends more time on the computer now than a few years ago, particularly with online social networking sites. She also didn't have physical education class every day last year.
Making exercise fun is important, because if you do, “you won't even realize if you're exercising,” she said.