Central fatigue is likely to occur when which of the following storage levels are depleted?

Central fatigue refers to the decrease in the ability of the central nervous system to activate the muscles, primarily due to changes that occur in the brain. This type of fatigue can significantly impact physical performance. When it comes to fuel storage in the body, carbohydrates, particularly in the form of glycogen stored in muscles and the liver, play a crucial role in sustaining energy during prolonged exercise.

As exercise continues, the reserve of glycogen diminishes, and when these carbohydrate stores become depleted, it can lead to a significant reduction in energy production. This depletion impacts brain function and can alter neurotransmitter levels, which collectively contribute to feelings of fatigue. In this state, the nervous system may struggle to effectively activate muscle fibers, thus leading to central fatigue.

While other substances such as creatine, branched-chain amino acids, and enzymes are important for energy production and overall metabolic processes, their depletion is not primarily linked to central fatigue as directly as glycogen depletion. Since carbohydrates are a primary energy source, especially during intense and prolonged physical activity, their depletion is a critical factor in the onset of central fatigue.