What is commonly referred to as "hitting the wall" in endurance activities?

The term "hitting the wall" is commonly associated with endurance activities and refers to a specific phenomenon that occurs during prolonged physical exertion, particularly in endurance sports such as marathons. This condition typically manifests when the body's glycogen stores in the muscles and liver become depleted, significantly impacting performance and energy levels.

Substrate fatigue is the most appropriate term in this context because it specifically relates to the depletion of energy substrates, namely glycogen, which the body relies upon during prolonged exercise. When these stores run low, athletes often experience a sudden onset of fatigue, a drop in performance, and an overwhelming sense of exhaustion, which is exactly what "hitting the wall" describes.

In contrast, acute fatigue generally refers to a short-term inability to perform, often due to intense exertion, but does not specifically imply a depletion of glycogen stores. Metabolic fatigue involves a broader range of physiological changes that affect energy metabolism, while neuromuscular fatigue pertains to decreases in muscle force production due to central and peripheral nervous system factors, which do not directly correlate with the specific experience of "hitting the wall" tied to substrate depletion.