Impacts in sport can cause severe and fatal head, spinal and thoracic injuries. As sports have developed during the last half century, methods have been developed to control injury risks, such as rule modifications, helmets, padded clothing and training. The biomechanics of severe injury is well understood through investigations of motor vehicle accident trauma. Research into sports injury can assist in reducing injury risks and also identify mechanisms and tolerance limits for lower severity injury. The paper provides an overview of impact injury risks in a range of sports, including concussion, commotio cordis and spinal cord injury. The main focus of the paper is injury control methods, their biomechanical bases and their success in reducing injury. Successful methods have been developed that include breakaway bases and helmets. Biomechanics plays an important role in quantifying physical hazards, developing interventions, methods for testing their performance, and assisting in field research.