How recreational marathon runners hit the wall: A large-scale data analysis of late-race pacing collapse in the marathon

Abstract

Introduction: In the marathon, how runners pace and fuel their race can have a major impact on race outcome. The phenomenon known as hitting the wall (HTW) refers to the iconic hazard of the marathon distance, in which runners experience a significant slowing of pace late in the race, typically after the 20-mile mark, and usually because of a depletion of the body's energy stores.

Aim: This work investigates the occurrence of significant late-race slowing among recreational marathoners, as a proxy for runners hitting the wall, to better understand the likelihood and nature of such slowdowns, and their effect on race performance.

Methods: Using pacing data from more than 4 million race records, we develop a pacing-based definition of hitting the wall, by identifying runners who experience a sustained period of slowing during the latter stages of the marathon. We calculate the cost of these slowdowns relative to estimates of the recent personal-best times of runners and compare slowdowns according to runner sex, age, and ability.

Results: We find male runners more likely to slow significantly (hit the wall) than female runners; 28% of male runners hit the wall compared with 17% of female runners, χ2(1, N = 1, 928, 813) = 27, 693.35, p < 0.01, OR = 1.43. Such slowdowns are more frequent in the 3 years immediately before and after a recent personal-best (PB) time; for example, 36% of all runners hit the wall in the 3 years before a recent PB compared with just 23% in earlier years, χ2(1, N = 509, 444) = 8, 120.74, p < 0.01, OR = 1.31. When runners hit the wall, males slow more than females: a relative slowdown of 0.40 vs. 0.37 is noted, for male and female runners, when comparing their pace when they hit the wall to their earlier race (5km-20km) pace, with t(475, 199) = 60.19, p < 0.01, d = 0.15. And male runners slow over longer distances than female runners: 10.7km vs. 9.6km, respectively, t(475, 199) = 68.44, p < 0.01, d = 0.17. Although, notably the effect size of these differences is small. We also find the finish-time costs of hitting the wall (lost minutes) to increase with ability; r2(7) = 0.91, p < 0.01 r2(7) = 0.81, p < 0.01 for male and female runners, respectively.

Conclusions: While the findings from this study are consistent with qualitative results from earlier single-race or smaller-scale studies, the new insights into the risk and nature of slowdowns, based on the runner sex, age, and ability, have the potential to help runners and coaches to better understand and calibrate the risk/reward trade-offs that exist as they plan for future races.

Fig 1. The proportion of runners in the original dataset hitting the wall by slowdown (DoS) and minimum length (LoS) thresholds.

Fig 2. The proportion of male and female runners hitting the wall by (a) age range and (b) ability level.

Fig 3. The proportion of male and female runners hitting the wall based on the number of years before (<0) and after (>0) achieving their overall (estimated) PB: (a) shows the relevant proportions of runners hitting the wall for each year before and after a PB; (b) shows the aggregate proportion of runners hitting the wall during four periods, 4–9 years before/after a PB and 1–3 years before/after a PB.

Fig 4. The proportion of male and female runners hitting the wall based on the number of years before (<0) and after (>0) their overall (estimated) PB, and based on age and ability.

Fig 5. HTW dimensions (start, distance, slowdown) for male and female runners by age range and ability.

HTW Start refers to the average distance at which runners begin the slowdown that corresponds to their hitting the wall. HTW Distance refers to the length of this slowdown and HTW Slowdown refers to the degree of this slowdown, relative to their base-pace (that is, their average pace during the 5–20km portion of the marathon).

Fig 6. The finish-time and cost associated with hitting the wall for male and female runners by age range and ability.

HTW Time refers to the finish-time in minutes when a runner hits the wall. HTW Cost refers to the difference between a runner’s HTW Time and their estimated PB time. Rel HTW Cost refers to a runner’s HTW Cost as a fraction of their PB time.