Fuel(s) used for aerobic energy systems?

• A. Carbohydrate
• B. Carbohydrate and Fat
• C. Fat
• D. Protein

Answer: (B)

In aerobic energy production, the body uses oxygen to break down fuel substrates to make ATP. The main fuels are carbohydrate and fat. Carbohydrates provide glucose or glycogen that can be oxidized quickly to produce energy, which is especially important as exercise intensity increases. Fat, stored as triglycerides in fat tissue and intramuscular fat, provides a larger energy reservoir and supports energy production over longer, lower-intensity efforts, though it requires more oxygen and yields energy more slowly. The body adjusts the mix of these fuels based on how hard and how long you’re exercising. Protein can be used as a fuel only in very long-duration activities or under caloric deficit, but it isn’t a major supplier during typical aerobic work. So the aerobic system relies on both carbohydrate and fat.