Abstract
Current characterizations of chronic traumatic brain injury (CTBI) in boxing, football and other sports are reviewed in the context of the history of research on sub-concussive brain trauma in athletes.The utility of exposure models for understanding CTBI in boxers is examined and concerns regarding the paucity of findings supportive of an exposure model for CTBI in football players are discussed.Recommendations for development of exposure models for sport-specific phenotypic characterizations of CTBI are presented.