Résumé
This chapter presents a summary of our current understanding of energy‐production pathways during exercise of varying intensities. The basal metabolic rate (BMR) corresponds to the absolute or relative rate of energy expenditure at rest, in a thermoneutral environment. Whilst adenosine triphosphate (ATP) has several roles in cell structure and signalling, it is the only molecule (i.e. chemical energy) that can be used by the muscle to produce a contraction (i.e. mechanical energy). Muscle contraction relies on ATP breakdown. Interestingly, repeated bouts of high‐intensity exercise or high‐intensity intermittent training (HIIT) have been shown to be better than endurance training (submaximal intensities) at inducing fat loss. The magnitude and rate of adaptation of oxygen uptake is a key factor in performance. Oxidative phosphorylation, glycolysis and phosphocreatine (PCr) all work in conjunction, but their predominance in energy production depends first on exercise intensity and second on exercise duration.