The National Football League has joined the fight against childhood obesity with a campaign that goes beyond gym class and aims to get kids out of their chairs in the classroom.

New York Giants quarterback Eli Manning dropped by a Manhattan public school this week where he showed eighth-graders how to add some exercise to their math class. He had them perform squats, then count their own heart rates for 15 seconds and multiply by four to calculate their heartbeats per minute.

The stunt was part of the $1.5 million "What Moves U" campaign funded by the NFL and designed with the help of the American Heart Association to address the decline of physical education in schools.

Some 25,000 middle schools that are participating in the nationwide effort will get lesson plans intended to broaden physical activity in schools.

A language arts lesson has students create and perform a rap that demonstrates action verbs. A science lesson has kids play scooter tag, with one group of students representing cholesterol and another representing healthy hearts.

There will also be print and broadcast public service announcements and a Web site that will prod kids to get up out of their chairs after 10 minutes, said David Krichavsky, the NFL's director of community affairs.

"With the explosion of the childhood obesity statistics recently, our board of directors decided that we were in a particularly good position to make a statement and to make a difference," Krichavsky said.

Manning also paid a visit to the gym at Manhattan's Public School/Intermediate School 111. As hip-hop music blared from a boom box, seventh-graders went through a fitness circuit that included sit-ups, push-ups and jump-rope.

"It's great when you have the music and have a gym where you can do this, and just doing all sorts of different exercises and just get the heart rate up," Manning said. "It's fun, but they're getting a good workout."

Charlene Burgeson, executive director of the National Association for Sport and Physical Education, said youngsters should get at least 60 minutes of physical activity a day, a level achieved by only 36 percent of high school students.

"The concept of integrating it into kids' classroom time has a lot of benefits," she said.

According to the Centers for Disease Control and Prevention, 17 percent of U.S. youngsters are obese and millions more are overweight. Obesity can lead to diabetes, high blood pressure and cholesterol, sleep problems and other disorders.