Which substrates can be oxidized aerobically?

The correct answer is centered around the substrates that the body can utilize in the presence of oxygen during aerobic metabolism. Carbohydrates and fats are the primary substrates that can be oxidized aerobically, providing energy for prolonged, moderate-intensity physical activity.

Carbohydrates are broken down through glycolysis, entering the aerobic pathway when oxygen is present, leading to the production of ATP through the Krebs cycle and oxidative phosphorylation. Fat, particularly in the form of fatty acids, undergoes beta-oxidation before entering the same aerobic pathways, making it a significant energy source, especially during lower-intensity activities.

While sugars, proteins, and lipids do play roles in energy metabolism, not all of them are primarily oxidized aerobic for energy production. For example, proteins can be utilized for energy but are mainly reserved for when carbohydrate and fat stores are low, as they are more efficiently used for building and repairing tissues. Therefore, carbohydrates and fats stand out as the primary substrates for aerobic oxidation.