answer:I think you might really enjoy this Radiolab podcast about American football. If I recall correctly, one of the segments (Ghosts of Football Future) features people who played football when they were younger weighing the risks for their own children. While I was looking for that link, I happened across a recent CBC story about advances in football helmet design that have significantly reduced risks (locally) due to impact and twisting. But it’s unclear to me how quickly the use of new designs might become widespread. I assume that since there is so much direct contact (so to speak) between teams, it would happen, but my guess is that there’s probably very little top-down influence.