As stunts get more daring, injuries have multiplied -- prompting a new push for safety.

Patty Phommanyvong, a cheerleader for Marshall High School in Los Angeles, was thrust into the air while performing a stunt at a football game two years ago. The next thing anyone knew, she was limp. Her heart had stopped beating.

Paramedics were called, but by the time they got her heart restarted, her brain had been deprived of oxygen for too long and she was in a coma. Experts say she may have been inadvertently struck in the chest on her descent from the stunt.