What is the primary source of energy utilized during aerobic exercise?

During aerobic exercise, the primary sources of energy utilized are fatty acids and glucose. This is because aerobic exercise relies on oxygen to help convert these macronutrients into usable energy.

When the body is engaged in sustained, moderate-intensity tasks, such as running at a steady pace or cycling, it primarily uses fatty acids as a fuel source. These fatty acids are derived from the breakdown of fat stores in the body. In addition, glucose, which comes from carbohydrates, is also a significant energy source, particularly during the earlier stages of exercise or when the intensity increases.

Both fatty acids and glucose undergo oxidation processes in the presence of oxygen, which leads to the production of ATP (adenosine triphosphate), the energy currency of the cell. This ability to utilize both fat and glucose efficiently allows athletes to maintain performance levels over longer durations of exercise. Conversely, while proteins and ketones can serve as energy sources at certain times, they are not the primary fuels used during typical aerobic exercise.