A new study finds that getting kids into the gym or onto the playground could boost their grades.
 

The research, to be published in an upcoming issue of the Journal of Pediatrics, found that elementary and middle school students who weren't physically fit were more likely to fail both math and reading tests.

"Schools sacrificing physical education and physical activity time in search of more seat time for math and reading instruction could potentially be pursuing a counterproductive approach," says study lead researcher Dr. Robert Rauner of Creighton University and Lincoln Public Schools in Lincoln, Nebraska.

In the study, Rauner's team compared fitness levels and test scores among students in elementary and middle schools. Fitness was measured by a test known as a PACER, a timed shuttle run. Results shows that kids who were physically fit were 2.4 times more likely to pass math tests and more than twice as likely to pass reading tests than kids who were out of shape.

However, body mass index, a common measure of overall health, didn't have an effect on test scores, the researchers say. So while obesity is a hot button issue for kid's health, the findings suggest that aerobic fitness may have an even greater effect on academic performance than weight, the researchers wrote.