It does vary from sport to sport, but a few things come to mind. I think there is a move away from having full contact at the minor levels for collision sports, whether it be football or rugby. Part of the challenge is the traditions of the sport. I remember all the challenges we had, despite having solid data, to convince Hockey Canada to remove body checking at the younger ages. Eventually, through a lot of pressure, they came around.
The most vulnerable group are those who are young. I'm of course speaking more at the high performance level, but I see in my clinical practice that it's the young athletes who are the ones we are most worried about. It's about avoiding unnecessary exposures for them, and with rule changes.... Perhaps the type of sport they are in.... If they play flag football instead of tackle football, they can learn the skills. They can be active, and then later, when they have better neck strength, better balance, better proprioception and a more developed brain, they can decide on their own if they want to add higher-risk things like the collision sports.
I think that every sport is looking at what they are doing. Again, working in the CFL, every year there are rule changes, and the majority of them are actually based on how we can make the game safer. Every sport is doing that and trying to determine what they need to do to address this epidemic of sport concussion.
Then you have to overcome the traditions of the sport. Sometimes, it's a little tough to sell. Once it's in place, you have to get the referees that are going to enforce it, and you have to have the public that is going to accept it. All those are barriers, I would suggest.