I'm afraid I don't understand your point about concussions. Whacking your head at high speed into a hard surface is generally more dangerous when your head is bare than when it is helmeted. I've seen some really bad head trauma on skating rinks. Sonny Bono was killed when his head hit a tree (I think). Hitting my head like that without a helmet would have been have been a lot worse than it actually was (I believe.) Why do hockey players wear helmets?

cheers, Joe