Which process primarily occurs in low-intensity, prolonged activities?

In low-intensity, prolonged activities, the body primarily relies on fatty acid oxidation for energy production. This process occurs in the mitochondria of cells and allows the body to utilize stored fat as a significant energy source when oxygen is available.

During prolonged activities, such as long-distance running or cycling at a steady, sustainable pace, the demand for energy is lower than during high-intensity efforts. This enables the body to efficiently oxidize fatty acids through aerobic metabolism, resulting in a high yield of ATP while preserving glycogen stores. The increased availability of oxygen during these activities supports the aerobic energy system, making fatty acid oxidation the dominant fuel source.

In contrast, anaerobic glycolysis is more prevalent in high-intensity, short-burst activities where the energy demand exceeds the oxygen supply, resulting in energy being produced without oxygen. The ATP-CP system provides immediate energy for very short durations, typically under 10 seconds, and is not sustainable for longer, lower intensity efforts. Therefore, fatty acid oxidation is indeed the primary energy source utilized during low-intensity, prolonged activities, making it the correct choice.