Gym classes are being sacrificed across the country to save money and satisfy federal mandates stressing test scores in math and reading.

A little more than half of students nationwide are enrolled in a physical education class, and by high school only a third take gym class daily, according to the National Association for Sport and Physical Education.

And it's not like most kids are making up for lost gym classes by working out on their own time. More than 60 percent of children aged 9 to 13 do not participate in any organized physical activity during their non-school hours, the Centers for Disease Control and Prevention reported in August. And 23 percent do not engage in any free-time physical activity at all. Translation: Fewer kids are playing outside.

The phasing out of physical education comes at a time when doctors are warning parents and educators about the dangers of childhood obesity. Meanwhile, researchers are beginning to probe the relationship between fitness and excelling in school.

In a study conducted by the California Department of Education, higher academic achievement was associated with higher levels of fitness.

"This is something the Greeks knew," said George Ziolkowski, director of pupil personnel services at East Penn School District in Allentown, Pa., and a proponent of daily PE. "Let's start talking about how kids who are physically fit and feel better and have rest will do better in school."

PE Varies By State

Many public health experts and physicians recommend daily gym class from kindergarten through high school. But Illinois is the only state to require daily PE for all class levels.

Gym class requirements vary by state, but most states give kids ways to opt out. And the quality of physical education where it still exists, has suffered, said Paula Kun, spokesperson for the National Association for Sport and Physical Education.

"In elementary schools, you might have a regular teacher teaching phys ed," she said. "In high schools, it might be required only one out of four years."

But there are some signs that educators and legislators are trying to revive physical education.

Fifteen states are looking into changing their physical education requirements to encourage exercise. The federal government is handing out $15 million in grants to community programs that encourage physical activity.

And across the nation, in schools and communities, small-scale programs are trying to get kids moving, even if the state doesn't mandate it.

A Personal Touch

In Florida, where 58 percent of children do not attend gym class in any given week, health department officials did some research into why kids didn't like phys ed. They went first to a five-county rural area where 66 percent of adults were found to be overweight.

"The reasons they didn't exercise in school was because they didn't like getting dressed, getting sweaty during the day, and their classes were over-capacitated," said Cathy Brewton, coordinator for the obesity prevention program for the Florida Department of Health. "Kids said if they were going to do phys ed, they wanted to do something fun."

Enter Step Up to the Challenge. The health department gave pedometers to 6,000 students, teachers and staff. Participants are encouraged to get 10,000 steps a day, and grades will compete against one another. Students will receive Frisbees, water bottles and jump-ropes as incentive to exercise.

Some committed phys ed teachers are rising to the challenge of getting kids more active.

Patrice Lovdahl has taught gym at Rawls Springs Attendance Center in Hattiesburg, Miss., for 17 years. Her state has one of the highest incidences of childhood obesity and related problems. And though Mississippi doesn't require it, Lovdahl teaches gym every day, thanks to committed administrators, she said.

The key to keeping kids active is encouraging them to get exercise in all aspects of their lives, she says.

"I'll go to a soccer game or football game because I want them to know I want them to do things outside of class, too," she said. "We can make a difference here at school, but when they go home, if they're used to doing a certain thing, they're going to stick to that."