We will recruit basketball and soccer coaches and their athletes from Chicago public high schools. We will randomize teams to intervention and control groups. We will train intervention coaches to implement a 20-minute neuromuscular warm-up and tracked training costs. Control coaches will use their usual warm-up. All coaches will report weekly athlete exposures (AEs) and injuries resulting in a missed practice/game. Research assistants will interview injured athletes. We will compare injury rates between control and intervention groups.