The "wall"—that critical moment of physical and mental exhaustion—is not specific to the marathon, but occurs systematically around the two-thirds mark of any running event.

noli's read

The science of exertion confirms that the perception of fatigue is a dynamic phenomenon, often modeled by the "psychobiological model" (Marcora et al., narrative review). This model suggests that quitting or slowing down occurs when perceived effort becomes unbearable relative to motivation. While the concept of the "wall" is physiologically rooted in the depletion of glycogen stores during long efforts (over 2 to 2.5 hours), it is more subjective over shorter distances like the 10km. Exercise physiology studies (observational and experimental on pacing) show that runners unconsciously adjust their effort based on the remaining distance. Thus, the sensation of a "wall" around two-thirds of the way through an effort often corresponds to a period where the brain anticipates the finish while managing an accumulation of muscle metabolites. The assertion is therefore sound in terms of sports psychology, although the physiological cause differs between a 10km (acidosis/intensity) and a marathon (energy depletion).

the sources

No named source held this one up — that absence is part of the verdict.