What is the difference between aerobic and anaerobic metabolism?

Aerobic metabolism is distinguished by its requirement for oxygen to generate energy. This process utilizes oxygen to convert carbohydrates, fats, and sometimes proteins into ATP (adenosine triphosphate), which is the primary energy currency of cells. The presence of oxygen allows for the complete oxidation of fuel substrates, resulting in a higher yield of ATP compared to anaerobic processes, where energy is produced without oxygen.

The efficiency of aerobic metabolism stems from its ability to fully oxidize substrates, leading to approximately 36-38 molecules of ATP per glucose molecule, depending on the starting material used. This high yield is beneficial for sustained energy production, especially during prolonged, lower-intensity activities such as endurance exercise.

In contrast, anaerobic metabolism does not rely on oxygen, leading to the formation of less ATP, approximately 2 ATP per glucose molecule, through processes such as glycolysis and subsequent lactate production. While anaerobic pathways can generate energy rapidly for short bursts of high-intensity activity, they are not sustainable for extended periods. Thus, aerobic metabolism's reliance on oxygen and higher efficiency in energy production make it crucial for most prolonged physical activities.