ABSTRACT
Sport performance is often determined by a combination of both aerobic and anaerobic fitness. Immature children are more predisposed to aerobic metabolism and, as they mature, there is a shift towards an increased reliance on anaerobic glycolysis. Together with increasing size and mass, these changes have implications for the ability of young athletes to complete brief, prolonged and intermittent work. This chapter explores the natural development of the physiological determinants of both endurance performance and more intense exercise, together with the trainability of these qualities, throughout childhood and adolescence. In doing so the chapter shows that, for many young athletes, aerobic and anaerobic qualities can be simultaneously developed and guidelines are provided to help practitioners.
