Sure, you think, my kid's on a football team. That takes care of his exercise needs, right? Probably not.
"There are these bursts of activity," says Jim Sallis, a professor of family and preventive medicine at the University of California, San Diego. "But if you think about it, one hour of playing football out on the field means that the vast majority of that time is spent standing around waiting for the next play."
And that's a problem, federal health officials say, because children need at least one hour of moderate to vigorous physical activity every day.
"We know that physical activity in childhood strengthens your bones, increases your muscle mass," says Tala Fakhouri, an epidemiologist with the Centers for Disease Control and Prevention. "It also has effects on psychological well-being in kids and teens. It increases their capacity for learning, their self-esteem and it may also help them deal with stress."
But just one in four young teenagers between ages 12 and 15 actually get that one hour of exercise every day, Fakhouri says. She analyzed federal health data gathered from 800 teenagers in 2012.
While kids may be active in childhood, it's typical to see a decline as they move into their teen years. "We know, for example, that sedentary behaviors like watching TV are the single biggest contributor to physical inactivity in adolescence," Fakhouri says.
But it's not that teenagers no longer enjoy sports.
In the study, teenage boys said their favorite physical activities outside of gym class were basketball, running, football, bicycling and walking. Girls favored running, walking, basketball, dancing and bicycling.
Most studies of physical activity find boys more active than girls, and this one was no different. It found that 27 percent of boys and 22.5 percent of girls got the recommended one hour of exercise daily. That includes gym class, organized activities and play.
It's not necessarily teenagers' fault that they're not more active, researchers say.
Parents worry about safety when their kids go outside. They worry about bullying from other kids and crime in urban neighborhoods. Sallis adds that a surprising number of parents are concerned about traffic. "They don't want their kids to go out because traffic is so bad. There's no safe place to cross the street," he says.
But organized classes or teams aren't the only option.
Families can make small changes in their schedule to build in more exercise, Fakhouri says. "You can take a long walk after dinner. You can take your dog on long walk. Play basketball, dance together."
And with many schools reducing or cutting out PE, Sallis says parents may have to put pressure on the schools, too.
"Look at what's happening in PE," Sallis says. "If they're not going out at all or very much, complain about that. If you see PE class and it's not very active, inform the principal that that's not acceptable."
Bottom line: Physically active kids become physically active adults. And that's another critical reason, Sallis says, to help your kids get out and get moving.
STEVE INSKEEP, HOST:
Today in Your Health, we look at teens who physically wear themselves down and also, teens who are not active enough. A recent national survey finds the majority of young teenagers do not get the exercise they need, as NPR's Patti Neighmond reports.
PATTI NEIGHMOND, BYLINE: Federal health officials recommend children take part in at least one hour of moderate to vigorous physical activity every day. Epidemiologist Tala Fakhouri, with the Centers for Disease Control and Prevention, says that's because the benefits of exercise for kids are well-known.
TALA FAKHOURI: We know that physical activity in childhood strengthens your bones, increases your muscle mass. But it also has effects on psychologic well-being of kids and teens. So we know it increases their capacity for learning, increases their self-esteem. It actually may help them deal with stress.
NEIGHMOND: But Fakhouri says only 1 in 4 teens between 12 and 15 actually get that one hour of exercise every day. She looked at federal health data gathered from 800 kids who answered questionnaires in 2012. She says that while kids may be active in childhood, typically there's a decline as they move into their teenage years.
FAKHOURI: We do know, for example, that sedentary behaviors - like watching TV - is the single most contributor to physical inactivity in adolescence.
NEIGHMOND: And even when kids are active, they're often not active enough. Take the example of football, the third most popular activity for boys. Jim Sallis is a professor of Family Medicine at the University of California, San Diego.
JIM SALLIS: There's these bursts of activity. But if you think of an hour of playing football out on the field, the vast majority of that time is spent standing around, waiting for the next play.
NEIGHMOND: Overall, Sallis says, the findings are worrisome in the midst of a childhood obesity epidemic. A study just last week showed young, overweight children risk being overweight for a lifetime. The federal data also show the more a child weighs, the less likely they are to be physically active. Sallis says there are other obstacles as well. Many parents worry about safety. They worry about crime in urban neighborhoods and other problems.
SALLIS: And surprising amount of concern with traffic, among parents. They don't want their kids to go out because the traffic is so bad, or there's no safe place to cross the street.
NEIGHMOND: Bit by bit, Sallis says, it's getting more and more difficult for kids to get the exercise they need, which is one reason why so many end up in organized, supervised activities like sports teams or dance and gymnastics classes. But if getting children back and forth to activities like that are problematic for parents, researcher Fakhouri says there are other small changes families can make.
FAKHOURI: You can take a long walk after dinner. You can take your dog on a long walk. You can play basketball with your kids. You can dance at home. There are certain things that a family can do together to increase the levels of physical activity of their children.
NEIGHMOND: And with many schools reducing or cutting back P.E., Jim Sallis says parents may have to put pressure on the schools.
SALLIS: Go to the child's school, and look at what's happening in physical education. If they're not going out at all or very much, complain about that. If you see a P.E. class and it's not really very active, inform the principal that that's not acceptable.
NEIGHMOND: Physically active kids become physically active adults - another reason, Sallis says, to help your kids get out and get moving.
Patti Neighmond, NPR News. Transcript provided by NPR, Copyright NPR.