Policy change eliminating body checking in non-elite ice hockey leads to a threefold reduction in injury and concussion risk in 11- and 12-year-old players - Black, A. M.; Macpherson, A. K.; Hagel, B. E.; Romiti, M. A.; Palacios-Derflingher, L.; Kang, J.; Meeuwisse, W. H.; Emery, C. A. (British Journal of Sports Medicine, 2016)