Pop Warner, the nation's oldest and largest youth football organization, is requiring a note from a doctor before letting anyone who's suffered a head injury back on the field.

"It takes all the pressure off a coach," said Jon Butler, Pop Warner's executive director. "There is no decision -- the child is out until being signed off by a trained medical professional."

The organization also announced Thursday the creation of a national medical advisory board. The chairman is Dr. Julian Bailes, who works with the NFL Players Association on concussion-related issues and is chairman of neurosurgery at West Virginia University's medical school.

"The NFL, NCAA and national federation for high schools have all made changes, and we want to carry that down to youth football," Bailes said. "We want to be responsible and responsive."

Bailes said there are fewer concussions among youths than at higher levels "just because the athletes are smaller and they don't generate the high-velocity impacts."

"But sometimes," he added, "the recognition of the occurrence of a concussion can be more difficult in a youngster, and we worry about the vulnerability of the younger brain."

Another board member is Dr. Stan Herring of Seattle, a leading advocate for a law requiring clearance by a doctor before kids who have suffered a head injury can return to sports.

It's called the Lystedt Law, named for one of Herring's patients who returned to a middle-school football game shortly after sustaining a concussion, then suffered another head injury. He went into a coma for three months and remains unable to care for himself. Washington was the first state to pass the law, and more have followed, with NFL commissioner Roger Goodell among the proponents. Herring also is pushing for a federal version.

Butler said Pop Warner based its written-consent rule on the Lystedt Law, then added provisions for situations common to their organization. An example is that when the parent of the injured player also is the head coach, the responsibility of monitoring the injury falls to an assistant coach.

Other members of the advisory board are Dr. Lawrence Lemak, founder of the National Center for Sports Safety and the Alabama Sports Foundation, and Dr. Arthur Day, vice chairman of the neurosurgery department at the University of Texas Health Science Center in Houston.

Pop Warner officials estimate more than 280,000 kids play in their football leagues across 43 states. The rules and medical board cover another estimated 190,000 girls involved in Pop Warner cheerleading and dance programs.