Throughout the twentieth century, interest in sport has evidenced a major increase worldwide and a new field of sports medicine has emerged. Sport spectators hip has been stimulated in part by the increased ease of international travel and the intro­ duction of new means of communication. Interest in professional sports and in such events as the World Cup and the Olympic Garnes has never been higher and the general popularity of sports has drawn increasingly greater numbers of young people to sports participation. Interest in sports participation has been strength­ ened both by the provision of numerous sports facilities to populations throughout the world and the accumulating information base that relates regular participation in programs of sport and exercise to health enhancement. Along with in­ creases in interest and participation has corne a need for a better understanding of the physiological changes accompanying muscular activity and of the trauma that can result from both competitive sport and recreational exercise.