A new national study finds as children age, they get less and less exercise, with fewer than a third of kids meeting the recommended physical activity guidelines by the time they’re 15 years old.

Dr. George Phillips, a pediatrics professor at the University of Iowa Children’s Hospital, says childhood obesity often leads to illness and chronic diseases. Phillips says it’s not a surprise, because at that age, the emphasis in the school moves away from incorporating physical education and recess on a regular basis to more time devoted to meeting academic requirements. Studies suggest children need a minimum of 60 minutes of moderate-to-vigorous physical activity every day.

Phillips says kids are more often finding themselves sedentary — either doing homework, surfing the ‘net or watching the tube. Screen time, whether it’s in front of the TV or computer, is taking up so much time for kids, Phillips says they need to remember it’s important to turn off the video games and computers and get outside for some physical activity. He says it’s an opportunity for the entire family to bond, even if it’s an after-dinner walk around the block. He says parents sometimes need to get creative to incorporate physical activity into their family’s day.

"Look for ways to make it more systematic, to plan ahead and just like you plan other family activities, plan time for good physical activity, hopefully 60 minutes a day at least on average, so our kids do get that good exercise," Phillips says.

The seven-year study, published this week in the Journal of the American Medical Association, found that while 90% of nine-year-olds get a couple of hours of exercise most days, fewer than three-percent of 15-year-olds get enough.