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Soccer is the world's game, played by 120 million people around the world and 16 million in the United States. It is unique in that it forbids the use of the upper extremity, other than by the goalkeeper or when throwing the ball into play from the sideline. It is also unique in that it is the only sport in which the head is purposefully used to strike the ball. As sports medicine has evolved, so has our curiosity about how certain sport-specific skills or protective equipment might change the injury profile of a sport. For soccer, there has been some concern that heading may be associated with the development of cumulative traumatic brain encephalopathy, or the "punch drunk" syndrome described in boxers. This article discusses this question in detail, with a critical look at the literature and an emphasis on the prospective data.

(C) 2004 American College of Sports Medicine