Children are not mini-adults. They are growing and maturing at their own individual rates and their physiological responses to exercise are dependent on a large number of variables as they progress through childhood and adolescence into adult life. Understanding has been limited by the fact that measurement techniques and equipment developed for use with adults are often not appropriate or even ethical for use with young people. These issues are addressed in this book which provides an analysis of physiological responses to exercise in relation to age, growth, maturation and sex. The physical and physiological changes that occur during growth and maturation and the potential effects that these changes might have on thermoregulation and effort perception during exercise are explored. Intensive training and participation in sports competitions at a young age are examined with particular reference to appropriate training programmes, injury risk, eating disorders and the female triad.