ABSTRACT
This chapter is concerned with the physiological responses of the child to physical activity. Changes with growth and maturation are central to the discussion and differences between children and adults are highlighted. The chapter opens with an explanation of the three processes by which energy for muscular contraction is generated: the ATP-CP and lactacid anaerobic systems and the aerobic system. The relationship between energy systems and muscle fibre type is discussed. The aerobic and anaerobic energy systems are then described in greater detail with consideration of the means by which these may be measured. Changes in maximal oxygen uptake during development are discussed before a more detailed consideration of the cardiovascular and pulmonary components of the oxygen transport system which serves to illustrate more clearly child-adult differences. The measurement of blood lactate responses to exercise provides an important additional assessment of aerobic capabilities. The necessity for child-specific reference values when interpreting children’s blood lactate responses is emphasized, as is the need to consider carefully the impact of methodological factors upon the blood lactate measures obtained. The measurement and interpretation of children’s anaerobic power and capacity are then examined. Children’s clear inferior ability to perform intense anaerobic exercise compared with adults is described but as highlighted, the methodology used to attempt to explain and quantify these differences has serious limitations.
