Diving into Ultramarathon DNF Knowledge – iRunFar

Some buddies and I made the street journey to the 2016 Bighorn Path 100 Mile, and all of us acquired shirts with the course profile on the again. When one among my buddies returned house with the shirt and a since-avenged DNF, his sons favored to level on the highest peak on the course profile and say: “That is the place you failed.” I believe they had been onto one thing — along with simply being laborious on their dad — so let’s attempt to pinpoint what goes right into a DNF.

“Didn’t end” (DNF) is an end result that runners typically need to keep away from, so it may be helpful to grasp the place the dangers of getting a DNF are increased. Are there specific traits a race might need that can drive up the DNF charge? Are there factors in a race the place a DNF is extra doubtless? Strap in for a journey of discovery.

The Methodology

This text attracts on two datasets: one composed of outcomes from 25 races, and a smaller dataset with 10 years value of splits for a specific race. For each datasets, I managed for distance by specializing in 100-mile races. Please don’t take that as a snub towards different race distances — we love all distances however must create information boundaries someplace.

For the dataset composed of outcomes from 25 races, I deliberately selected races with some selection of their areas, terrain, elevation, and begin occasions (1). My dataset remains to be admittedly small, as a result of it’s comprised of simply 25 races and solely their outcomes from 2023. Nonetheless, it’s a superb start line for a just-for-fun evaluation that offers us one thing to debate with our buddies on the following future. I chosen races that had been:

• A part of the World Path Majors
• A part of the UTMB World Sequence
• On “UltraRunning Journal’s” checklist of the most important North American ultras in 2023, and/or
• Occasions I’ve run personally and I wished to point out them some love

The DNF charge for every occasion was calculated by dividing the variety of runners who DNFed by the variety of individuals who began the race. Runners who didn’t begin subsequently don’t issue into the DNF charge.

Do Sure Components Affect DNF Charges?

Reasonably than preserve you in suspense, I’ll let you know proper now: “being the 2023 Western States 100” was the one issue that had a discernible influence on DNF charges on this specific dataset. In 2023, over 85% of runners who began the Western States 100 crossed the end line in time to obtain their belt buckle. The proportion of runners who obtained a DNF was 13.5%. That was an unusually excessive finisher charge: for the earlier 20 editions of the race, the typical DNF charge was 27%.

The 2023 version of Western States was thought of a very mid when it comes to the climate forecast. There could also be different components that give the occasion the next finisher charge (and decrease DNF charge) than another 100 milers.

For instance, Western States requires runners to qualify to run the occasion. The challenges of gaining entry to Western States additionally imply runners don’t have any assure of having the ability to strive once more subsequent yr — or ever — so the runners lucky sufficient to begin the race can be significantly motivated to coach effectively.

Lastly, Western States maintains a waitlist, so runners who imagine they gained’t end the race have the choice of constructing one other runner’s dream come true by withdrawing from the race prematurely, so one other runner can have the chance as an alternative.

By way of some mixture of those components, individuals within the 2023 version of Western States collectively crushed it.

Past this remark, there have been no apparent or statistically important developments amongst any of the components I examined. Whereas the races within the dataset had some notable variations amongst them, most had DNF charges inside a specific vary. The typical DNF charge within the restricted pattern dataset was 38%, and also you’ll see within the distribution chart under that almost all races had DNF charges in that ballpark.

Distribution of DNF Charges Among the many 25 Races within the Pattern Dataset

DNF Charges by Complete Elevation Change

There isn’t a compelling or statistically important development in how elevation change impacted the DNF charge in our dataset.

For instance, the Extremely-Path Snowdonia by UTMB 100 Mile had the very best DNF charge in 2023 of races within the dataset, at 59%, and had 62,336 ft (19,000 meters) of elevation change. It eclipsed the Extremely-Path Kozciuszko by UTMB 100 Mile in each respects, as that race had simply 3,937 ft (1,200 meters) of elevation change and a DNF charge of 31% in 2023.

However there are each mountainous and relatively flat or hilly races inside the 30 to 49% vary for DNF charges.

Correlation between DNF Price and Complete Elevation Change for Every Race

DNF Charges by Time Cutoff

Affording runners extra time to cowl 100 miles doesn’t appear to be a surefire option to cut back DNF charges. A 30-hour cutoff was the smallest period of time races on this dataset provided for runners to achieve the end line. Among the many races with that cutoff on this dataset — the South Downs Manner 100 Mile, Western States 100, Hennepin 100 Mile, Javelina 100 Mile, Rocky Racoon 100 Mile, and Leadville 100 Mile — the DNF charge ranged from 13% proper as much as 56%.

Correlation Between DNF Price and Time Cutoff for Every Race

DNF Charges by Race Begin Time of Day

In pre-race interviews for UTMB, North American athletes will typically confer with the problem of racing an ultramarathon with a night begin. Whereas the UTMB begins at 6:00 p.m. native time, the Rocky Racoon 100 Mile, for instance, begins at 6:00 a.m.

Early begin occasions had been pretty frequent among the many North American races on this dataset — although a lot respect to the Black Hills 100 Mile for letting runners sleep in earlier than their comfy 10:00 a.m. begin time.

Whereas particular person runners are more likely to have opinions on the best time of day to begin a 100-mile race, the dataset didn’t recommend that begin time has an influence on DNF charges.

Correlation Between DNF Price and Begin Time for Every Race

Whither the DNF?

I used to be curious to know the place the “hazard zone” for dropping from a race may be, so I pulled up the splits for the Superior Fall Path Race 100 Mile. I selected this race as a result of it’s a private favourite, and the race director publishes the race splits in a constant and accessible format. The 103-mile course is more difficult within the second half, with essentially the most technical terrains and largest climbs concentrated in that portion.

I might like to broaden upon this evaluation in a future column and incorporate information from extra races, however the information from the Superior Fall Path Race 100 Mile confirms what I’m certain you intuitively suspected. You’re probably to DNF your 100-mile race throughout that part of the race when your legs are drained, however you continue to have many miles to cowl.

I counted the entire DNFs, by help station, for this race for the years the place splits can be found on-line — 2014 to 2023. I plotted them within the chart under to point out the factors within the race which have the most important proportion of all DNFs.

As a technical observe to my fellow superfans of this occasion, as a result of runners are strongly discouraged from dropping out on the distant Sonju Lake Highway help station and timing information is usually unavailable for that help station, I mixed any identified DNFs for Sonju Lake Highway with the DNFs on the subsequent help station, Crosby-Manitou at mile 62.9.

Additionally observe that each one DNFs for this race are marked to have occurred at help stations.

DNFs on the Superior Fall Path Race 100 Mile, From 2014 to 2023, by Mile/Support Station

However Why Did They DNF?

Outcomes and splits solely inform a part of the story in the case of a DNF. To essentially perceive why runners DNF, we have to take a look at the qualitative information as effectively.

To the reduction of Instagram ultrarunning meme account @yaboyscottjurek, we don’t have to learn a bunch of nine-part race recaps on Instagram to grasp the explanations runners don’t end a 100 miler.

The American Path Working Affiliation (ATRA) conveniently aggregated the experiences of roughly 1,200 survey respondents in a 2022 article on the subject. ATRA’s survey offered runners with an inventory of causes they may DNF a path race of any distance, and runners might choose the entire causes that contributed to any of their previous DNFs. You may see the leads to the desk under.

Closing Ideas

We could revisit this matter once more in a future column, as a result of there are extra questions I want to reply. For instance, are DNF charges impacted by whether or not:

• Runners want a qualifier to get into the race?
• The race is kind of aggressive?
• The race is a bucket-list kind race with a hard-to-enter lottery or important and costly travels to?
• Races that entice extra “repeat offenders” have decrease DNF charges, maybe as a result of extra individuals have prior expertise with the course?
• There are significantly troublesome climate or course circumstances, like excessive warmth, a giant storm, or extra snow or mud?
• The race is lengthy or brief?

Moreover, I might like to know if there’s a specific time of day when runners are probably to DNF, corresponding to in a single day or maybe within the warmth of the day.

I think about many readers are serious about DNFs for a similar purpose I’m: We want to complete our races. We hope that by understanding DNFs, we cut back the chance of it occurring to us.

Whereas I can’t think about many — if any — runners begin a 100-mile race with the intention of getting a DNF, ultrarunner, race director, and podcaster by way of the enterprise Ten Junk Miles Scott Kummer jogged my memory that the DNF represents a vital facet of the ultramarathon.

I requested him concerning the DNF charge for the Badger Path Race 100 Mile, which he organizes. With 18 help stations and a 38-hour restrict to cowl 100 miles on comparatively flat rail trails, it’s an occasion that we now have beforehand described as “finisher-friendly.” The race nonetheless had a 26% DNF charge in 2023 — 34 DNFs amongst 133 individuals — which places its DNF charge inside the identical vary because the occasions we examined above.

However, as Kummer identified, among the runners interested in the Badger Path Race 100 Mile particularly select that race over different ultramarathons as a result of their possibilities of ending an occasion with much less beneficiant cutoffs on extra technical trails are too low.

Whatever the occasion or the terrain, many runners are drawn to occasions the place they’ve a professional likelihood at reaching their objectives, however they’re challenged sufficient that getting a DNF stays a definite risk.

Talking for myself, this can be a helpful reminder. When life will get busy and coaching falls by the wayside, it’s simple to get anxious concerning the growing odds that I gained’t attain my race objectives. Finding out DNFs helps me make peace with my very own, and provides me a deeper appreciation for the way the complete level of coaching for a difficult race is to spend time pushing the boundaries of our potential, whereas repeatedly coming to phrases with these limits.

It applies to life exterior of operating, too. Heck, I technically DNFed this text as a result of I missed a time cutoff for offering it to my editors and I nonetheless have to let you know about…

Name for Feedback

• Do you contemplate the proportion of runners who DNF when judging a race’s issue?
• What’s your private expertise with DNFs?
• We could must take one other take a look at DNFs sooner or later. What different developments would you prefer to dig into?

Notes

1. In alphabetical order, the 25 races (all 100 milers) are: Bighorn Path, Black Hills, South Downs Manner, Doi Inthanon Thailand by UTMB, Grand Raid des Pyrénées, Grindstone by UTMB, Hennepin, Istria 100 by UTMB, Javelina, Julian Alps Extremely-Path by UTMB, KAT100 by UTMB, Kullamannen by UTMB, Leadville, Mountain Extremely-Path by UTMB, Good Côte d’Azur by UTMB, Québec Mega Path, Rocky Raccoon, Run Rabbit Run, Superior Fall Path Race, Path Alsace Grand Est by UTMB, Extremely-Path Cape City, Extremely-Path Kosciuszko by UTMB, UTMB, and Western States.