Increasing the number of young children who exercise for just under a half hour a few times a week could save tens of billions in medical costs over their lifetimes, researchers said Monday, May 1, according to AFP.

Currently, just 32 percent of U.S. children aged eight to 11 get enough exercise, said the report in the journal Health Affairs.

The minimum guideline of 25 minutes a day, three days a week, was established by the Sports and Fitness Industry Association.

But if even just half of children exercised that much, the nation could avoid $21.9 billion in medical costs and lost wages over the course of their lifetimes, said the report by researchers at Johns Hopkins University's Bloomberg School of Public Health.

And if 100 percent of all kids in that age range did, $62.3 billion could be averted and 1.2 million fewer youths would be overweight or obese.

"Physical activity not only makes kids feel better and helps them develop healthy habits, it's also good for the nation's bottom line," said lead author Bruce Lee, executive director of JHU's Global Obesity Prevention Center.

"Our findings show that encouraging exercise and investing in physical activity such as school recess and youth sports leagues when kids are young pays big dividends as they grow up."

About one in six US youths aged two to 19 are overweight or obese, according to the US Centers for Disease Control and Prevention.

The CDC defines being "overweight" as having a body mass index -- a ratio calculated using measures of height to weight -- that is between 25 and 30.

Being "obese" means having a BMI higher than 30. The normal BMI range is 18.5-24.9.