The storage of what energy is most associated with premature fatigue during both aerobic and anaerobic exercise?

Glycogen is the primary storage form of carbohydrates in the body and plays a crucial role in energy production during both aerobic and anaerobic exercise. During physical activity, especially prolonged or intense exercise, the body relies heavily on glycogen stores for fuel.

When glycogen stores become depleted, the body's ability to generate ATP – the energy currency for muscle contractions – is significantly impaired. This depletion can lead to premature fatigue, as the muscles may no longer have sufficient energy to sustain performance.

Although ATP and creatine phosphate are essential for immediate energy production, they are only available in limited amounts and are rapidly utilized during short bursts of activity. Amino acids are not a primary energy source during exercise; they are typically used for muscle repair and recovery. Therefore, glycogen depletion is the most prominent factor associated with premature fatigue during both aerobic and anaerobic exercise, making it the correct choice in this scenario.