Photo by Denise Denicolo (Pixabay)

Most experienced marathon runners know about “the wall”, although for novices or first-timers to the distance, there is a significant chance of hitting it inadvertently.

Hitting the wall can be defined as a significant slowing of pace, usually after the 32k, because of a sudden fatigue linked to the depletion of the body´s energy stores. In the worst cases it can incapacitate the runner to finish the race.

But what factors affect a marathoner hitting the wall?

It is usually accepted that poor race nutrition, inadequate pacing (starting too fast) and even psychological factors can be implicated. But experience is also important, as more experienced runners seem more capable to avoid the worst of it.

A recent study using data from 4 million race records from big city marathons has tried to determine where and how marathon runners hit the wall, according to parameters such as sex, age, and ability.

Thus, the study calculated the degree of slowdown using as a reference the base-pace during the 5km–20km (excluding the initial 5k because of usually crowded starts) portion and comparing it with the latest sections.

The main limitations of the study were their limited pacing data (5km splits), age ranges and an incomplete dataset of race records for every runner included.

Despite this, and thanks to the very large scale of the data, useful information was obtained.


Key findings

  • Male runners hit the wall more often (28%) than female runners (17%).
  • Male runners begin to slow down slightly later (29.6km) than female runners (29.3km).
  • Male runners suffer from this slowdown for longer than females (10.72km vs. 9.61km, respectively).Therefore, as females tends to recover more quickly, they usually finish faster than equivalent mean race-pace males.
  • The cost of hitting the wall in the finishing time, relative to PB times, is greater for faster runners.
  • Age plays a minor role in terms of the start, distance, and degree of slowdown in hitting the wall, although there is a strong relationship between these metrics and runner´s ability, estimated through arunner’s recent personal-best time (PB).
  • Starting too fast was associated with slower finishing-times, because it increased the likelihood of a runner hitting the wall later in the race.



How recreational marathon runners hit the wall: A large-scale data analysis of late-race pacing collapse in the marathon. Barry Smyth. PLoS One. 2021 May 19;16(5): e0251513. doi: 10.1371/journal.pone.0251513.

London Marathon (photo by Ian Wakefield)

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