"Tackling is dangerous. There's no safe way to do it. There are fair ways to do it, but there's no safe way to bring another man - or woman - to the ground and stop their momentum at the same time."

Dr Nowinski said there was no reason for children to play adult forms of any contact sport. "You just don't start hitting children in the head," he said. "When they're young, you don't play the adult, dangerous version of the game. What's the point? We're crazy to have children who are not getting paid and don't even understand what CTE means playing by the same rules as adults.