"These are numbers, not incidence, and you can see as you go through the years that it fluctuates," Meehan said. "It's not as if there's some mandatory reporting system and these athletes got followed over time. We don't have a denominator; we don't know how many players there were, and how many practices and how many games."
Case studies in the report included spinal fractures and bleeding or swelling in the brain, as well as one instance of a player recovering from a concussion who was cleared to play and suffered a brain bleed and stroke after a helmet-to-helmet collision.
In 1976, football organizations changed contact rules. Helmet-to-helmet contact became illegal, as did "butt blocking" (hitting the front of a player's helmet), face tackling and intentional spearing (initiating contact with the top of an opponent's helmet). Later, the "intentional" was removed and all spearing is now illegal.
Yet, Mueller said, "the problem is the way kids are playing: They're using the heads more. There was a reduction in the 1970s when the new rules went into effect. Now it's going back up.
Referees need to do a better job of enforcing safety rules, he said. "You don't see the flags being thrown after head-to-head contact. If you get 15-yard penalties or ejection from the game, you're going to see a difference."
Injury expert Meehan agreed with survey recommendations, such as better player conditioning to strengthen the neck muscles. Along with reducing cervical spine injury, that would lessen impact and slow the brain "spinning" that occurs in hits that cause concussions, he noted.
Coaches need to drill players to block with their shoulders -- not their heads -- and to tackle with their heads up, the report said.
High school concussion rules are being revised in many states: Players showing any signs of concussion must be removed from the game immediately and cannot return without being cleared by a health professional.
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