Aerobic Exercise

Aerobic exercise is planned, structured physical activity in which large muscle groups typically move rhythmically for a sustained period, with a substantial proportion of the required energy supplied through aerobic metabolism. Common forms include walking, running, cycling, and swimming. The term aerobic refers to the substantial use of oxygen-dependent metabolic pathways to regenerate ATP, the immediate energy source for muscle contraction .^1,2,3

During aerobic exercise, oxygen delivered by the respiratory and cardiovascular systems supports oxidative phosphorylation within mitochondria. Carbohydrates and fats can both provide fuel for this process. As exercise intensity and duration change, the relative contributions of these fuels and of different ATP-producing pathways also change .²

Aerobic exercise should not be interpreted as exercise powered exclusively by aerobic metabolism. Aerobic and anaerobic energy systems operate simultaneously, with their relative contributions depending strongly on exercise intensity and duration. Activities described as aerobic are generally those in which oxidative metabolism provides a substantial proportion of the energy required over the period of activity .²

Aerobic exercise is also distinct from aerobic fitness. Aerobic exercise is a type of physical activity, whereas aerobic or cardiorespiratory fitness describes the body's capacity to perform sustained activity that depends substantially on the respiratory and cardiovascular systems. Regular aerobic exercise can improve cardiorespiratory fitness, but the two terms describe different concepts .^1,3