ABSTRACT
This chapter discusses the importance of adenosine triphosphate (ATP) in human energy metabolism during exercise. ATP is the most important source of chemical energy in the body. The small endogenous ATP stores must be replenished continuously to avoid ATP depletion. Phosphocreatine (PCr) is a phosphorylated creatine molecule that is particularly important in resynthesising ATP during explosive, high-intensity exercise. ATP resynthesis from PCr is driven by the reaction between PCr and ADP, catalysed by the enzyme creatine kinase. To discuss the potential role of PCr depletion in exercise fatigue, it is useful to look at different types of exercise, namely maximal exercise and intermittent exercise. Carbohydrate, in the form of muscle and liver glycogen and blood glucose, is the primary fuel during exercise. The chapter focuses on the historical research that demonstrated the potential link between carbohydrate and exercise performance, and reinforced the perception that glycogen depletion causes fatigue, and more recent perceptions of the role of carbohydrate in exercise fatigue.
