Which factor is a common cause of muscle fatigue during prolonged exercise?

Fuel depletion is a common cause of muscle fatigue during prolonged exercise because the body relies on readily available energy sources, such as glycogen stored in muscles, to sustain performance. As exercise continues, these energy stores become exhausted, limiting the muscles' ability to contract effectively. When glycogen levels drop significantly, the muscles cannot produce sufficient ATP (adenosine triphosphate), which is essential for muscle contraction, leading to fatigue.

During prolonged physical activity, the continuous demand for energy can outpace the supply, resulting in decreased performance, increased perception of effort, and eventually, muscle fatigue. Maintaining a balance between energy consumption and replenishment is crucial for sustaining endurance and minimizing fatigue, as an inadequate supply of fuel can significantly impair muscle function.