Anaerobic Metabolism During Exercise

Abstract

AbstractA constant supply of adenosine triphosphate (ATP) is essential for function in all cells and especially so in skeletal muscle cells to power the contractions needed to enable the many forms of movement required in our daily lives and for exercise and sporting events. The muscle stores of ATP are small, and metabolic pathways must maintain the required rates of ATP resynthesis when the demand for ATP is high. Oxidative (“aerobic”) phosphorylation uses reducing equivalents from the metabolism of carbohydrate and fat to produce ATP and is the default energy system in skeletal muscle. Substrate-level phosphorylation or “anaerobic metabolism” also plays a very important role in supplementing or buffering ATP production when aerobic ATP production cannot meet the needs of an activity. These situations include the transitions from rest to exercise and from one power output to a higher one, exercise that demands ATP provision rates above what can be provided aerobically, and in situations of suboptimal oxygen supply. Anaerobic energy is provided from phosphocreatine and muscle glycogen breakdown (anaerobic glycolysis). These systems can provide energy very quickly and at very high rates but are limited to short periods of time during high intensity exercise due to substrate depletion and increasing muscle acidosis. In most exercise and sporting situations, energy provision is maintained by contributions from both the aerobic and anaerobic sources to ensure that ATP resynthesis closely matches the exercise ATP demand.KeywordsAnaerobic metabolismSkeletal musclePhosphocreatineAnaerobic glycolysisGlycogenCarbohydrateLactateATP provisionAcidosisHigh-intensity exercise