Although sports performance is multifactorial, it is clear that muscle performance plays a major role in most sports. Fatigue is associated with metabolic processes in the muscle and by manipulating these processes, exercise can be maintained for longer or power output and speed can be enhanced. The key metabolic factors in sustaining and modulating performance and endurance in sport are: ATP, phosphocreatine, lactic acid, glycogen, and carbohydrate. So in answer to the question “Can it all be explained by metabolism and its manipulation?” The answer should be that metabolism plays a major role in most performances and can explain a large part of performance in many sports. However, fatigue is a multifactorial process and it is the combined effect of all these factors that ultimately determine performance.