The 12-to-18-year-olds sustained primarily lower extremity injuries such as strains or sprains. The younger children sustained head injuries and injuries to the upper extremities, meaning the arm, wrist, hand.
Ten or 15 years ago, they were basically standing leading cheers on the sidelines. They weren't throwing each other up in the air, and they weren't forming tall pyramids. The injuries that can result are severe.
These injuries more than doubled during the 13-year period we studied.