Muscle metabolism during exercise

Ethical considerations and the lack, until recently, of accessible non-invasive techniques of interrogating exercising muscles have limited research into developmental muscle metabolism during exercise. Current evidence supports an anaerobic/aerobic energy metabolism interplay in exercise in which children present a relatively higher oxidative capacity than adolescents or adults. There is a progressive increase in anaerobic glycolytic flux with age at least into adolescence and, possibly into young adulthood. Independent effects of biological maturation on muscle metabolism during exercise remain to be empirically proven. An amalgam of findings from muscle fibre profiles, muscle enzymes activity, muscle energy stores, substrate utilization, phosphocreatine re-synthesis, and pulmonary oxygen uptake contribute to a plausible model of an age- and sex-specific developing metabolic profile but the precise mechanisms require further clarification. There is a persuasive argument that muscle fibre recruitment patterns are a fundamental component of age- (and perhaps sex-) related differences.