NEW YORK (Reuters Health) - Children who spend time outdoors after school are more likely to be physically fit, a new study shows.
Researchers found that Canadian kids who spent most of their after-school time outside were three times more likely to meet guidelines for daily physical activity and were in better shape than those who spent all of their after-school time indoors.
"This is just evidence reifying how powerful the outdoors is," lead author Lee Schaefer told Reuters Health. "If we can get students outside more often, they are going to be more active, which is going to benefit them in the long term."
Schaefer, from the University of Regina in Saskatchewan, and his colleagues studied 306 urban youths between 9 and 17 years old.
Participants wore devices that measured their steps for a week and reported the amount of time they spent outdoors after school, in both organized activities and free play.
Kids who reported being outside during most or all of their after-school hours got almost 20 more minutes of moderate-to-vigorous exercise per day compared with those who spent most or all of their time indoors, the researchers found. That was after taking into account children's age, sex and weight and the time of year.
"It's important for students to be outside because when they're in outdoor spaces, they're more active," Schaefer said. "What's really important about the study is not just that kids are moving more, but they're moving more in a moderate-to-vigorous way."
The U.S. Centers for Disease Control and Prevention recommends that children get at least one hour of moderate-to-vigorous exercise every day. But few kids living in developed countries meet those guidelines, the authors write in The Journal of Pediatrics.
Prior studies attribute children's generally low levels of exercise to a variety of factors, the researchers say, including the pervasiveness of videogames and computers as well as changes in the built environment, which includes parks and other green spaces.
Earlier studies found that youths get most of their moderate and vigorous exercise during school and average only 10 minutes a day after school, they add.
But increasingly stringent academic demands have led to less outdoor play time at school, leaving children even more deficient in that area, Schaefer said.
Given how much time children spend in school, school wellness policies should include increasing outdoor activity, the authors write.
Several groups have called for more outdoor time as a strategy to boost kids' physical activity levels, but evidence to support those calls had been lacking, they note.
The new study stops short of recommending ways to get children who tend to stay inside out the door. The researchers also don't know what the children who went outside were doing during that time.
"That's definitely what we'll be looking at in the future," Schaefer said.
There were no weight differences between children who spent their time indoors and outdoors, the study found.
Schaefer said he was a bit surprised by that finding. But, he said, "Weight is not always the best way to measure whether somebody's healthy or not. When we weigh somebody, we don't really know how much of that weight is fat or muscle."
"There's a lot we don't know yet," Schaefer said. "I would love to see students outside more."