Educated Guesswork

What's an ultramarathon?

Posted 2021-09-12

If you tell someone you run ultramarathons, it's pretty common for the next question to be "what's an ultramarathon"? This is a question with both a simple and a complicated answer. The simple answer is that an ultra is a race that's longer than a marathon, so technically I guess if you run a marathon and then run to your car, you've done an ultra marathon. The complicated answer is that there are a lot of different kinds of ultras and they vary on a number of axes.

Distance #

The defining characteristic of an ultra is just distance. The common ultra distances (from shortest to longest) are 50 km (31 miles), 50 miles (80 km), 100 km (62 miles), and 100 miles (160 km). You'll notice that these are all "natural" distances in one system or the other. Also, because many ultras are run on trails, it's often hard to measure the distance precisely so it's not uncommon to have some distance which is sort of approximately like one of these common distances (e.g., 85 km or 105 km) and even when the advertised distance is one of these common values, it's not too uncommon to see the distance actually be a bit off. Sometimes this is acknowledged (e.g., the Mogollon Monster calls itself a 100 miler but then says that it's more like 102 or 103) and sometimes the distances are just wrong.[1]

There are also much longer events, starting at 135 miles or so for the Badwater 135. 200 and 250 mile trail events are reasonably common in the US including Destination Trail (Bigfoot 200, Tahoe 200 and Moab 240) and Aravaipa (Cocodona 250). Even higher up we have stuff like the Megarace which is 3100km and the 3100 mile Srin Chinmoy transcendence race, which takes 52 days.

Terrain #

Like other running, ultras take place on three major types of terrain: track, road, and trail.

Track isn't that common and is used mostly for record attempts of one kind or another (e.g., the 12 hr world record) because it's very controlled and flat.

Road should be pretty self-explanatory: you run on the road just like with 10Ks, marathons, etc. One difference here is that the roads often aren't closed: ultras are a lot smaller than shorter road races and take longer so it's a bigger deal to close them. One unusual road ultra is the SF Ultramarathon in which you run the SF marathon course (with some variations) backwards and then run the SF Marathon after.

In the US, at least, most ultras are on trail (personally, I won't road race without some extenuating circumstances, too boring and too hard on the legs even at slow paces). The two big variables are surface and climbing. First, the actual trail surface can vary from from gravel trail (e.g., Umstead 100) to incredibly rocky (e.g.,Zane Grey)[2] Sometimes you'll get both in the same race, as with JFK 50 which has about 15 miles on the technical Appalachian trail ("technical" is runner jargon for lots of rocks and/or roots) followed by 35 miles on the smooth C&O canal towpath.[3]

The other big variable is how much climbing (jargon: "vert") there is. There's an incredibly broad range here, from nearly flat (<60 feet per mile at Tunnel Hill) to ridiculously hilly (>300 ft/mile at Ultra Trail de Mont Blanc or Hard Rock 100) and then to truly ridiculous (>500 ft/mile at Barkley). Roughly speaking, >150 ft/mile is considered a lot of climbing and >200 ft/mile would be a very hilly event.

As a rule of thumb, West Coast US races tend to have fairly non-technical trail (though sometimes rocky) with a lot of vert, mostly in sustained climbs. East Coast US races tend to have flatter races with more technical trails with a lot of rocks and roots. When there are climbs they tend to be shorter.[4]. A number of Western events are also at altitude, especially in the Rockies. European events often take place in mountainous regions with a lot of vert and tricky trail, which seems to cause some Americans trouble (no American man has ever placed higher than third at UTMB, though American women have done quite well, with the phenomenal Courtney Dauwalter having won twice, most recently breaking the course record.)

Format #

Like most road races, most ultras are run in a fixed distance format with the winner being whoever finishes first. You can of course stop at aid stations or in longer ultras, lie down and sleep, but the clock is running the whole time, so when you're not moving you're falling behind (good advice is to keep moving as much as you can, because even if you're walking you're doing better than standing still).

Some races are fixed time (e.g., 24 hours) instead of fixed distance with the winner being whoever goes the furthest in a given time. This kind of race is usually run on some kind of shortish course, like a track or short loop of a mile or so; that makes it easy to keep track of where people are and also makes it easy to just stop whenever time expires. Another advantage of this format is that you can have a single set of fixed aid stations so runners can have food available to them more or less whenever the want because they're passing it every 2-15 minutes depending on the course and their speed.

Less frequent are stage-style races in which every day there's a fixed course that you have to run, but then you stop and take the night off. The winner is then determined by combining the stage results, either by minimum time or by allocating points for each stage. An example of this is Marathon des Sables (MdS).

Recently, a new style of "backyard ultra" has taken off, inspired by Big Dog's Backyard Ultra. This is a somewhat unusual format where there is a 4.16 mile loop that the contestants have to finish every hour. You start every loop together and keep going until only one person is left. Because you have to start every hour, it's not possible to get much rest even if you go fairly fast. At this point, the winners are doing 68+ hours (280+ miles). Not for me, I like to race and then sleep in my own bed, not stay up for 3 days straight.

Ultra-Adjacent Stuff (FKTs, Mountain Running) #

There's a fair amount of overlap between ultra and shorter than ultra mountain races (lots of climbing and on mountains) such as Pike's Peak Marathon, Sierre-Zinal, Marathon de Mont-Blanc, etc. For instance, ultra legend Killian Jornet has won UTMB, Hardrock, and Western States but has also won Sierre-Zinal (31 km with > 2000 meters of climbing) an unbelievable 9 times. This is a bit more of a European thing than an American one, though more Americans seem to be going to Europe to race now.

Another ultra-adjacent race type activity is putting up "fastest known times" (i.e., records) for specific trails. There are hundreds of trails with FKTs (fastestknowntime.com is the go-to site) on routes big and small, but many of the famous ones are now held by ultrarunners, including the Pacific Crest Trail (Tim Olson), Appalachian Trail (Karl Meltzer), John Muir Trail (Francois D'haene for South to North supported), and Rim-to-Rim-to-Rim (Jim Walmsley) There was a lot of this in 2020 because so many races were canceled because of COVID-19, including Corinne Malcolm on the Tahoe Rim Trail and and Tim Olson on the PCT, as well as Scott Jurek's partial attempt on the Appalachian Trail covered in the NYT

FAQ #

Really long distance running is kind of a foreign idea for most people and so naturally they have questions. Below I try to answer some of the most common ones.

Are you running the whole time? #

You're mostly moving the whole time. People will often hike the uphills (see below) and stop at aid stations to grab food, refill their bottles, change their shoes, etc. but mostly you want to keep moving.

Do you sleep? #

Generally, on anything less than a 100 miler you wouldn't sleep at all. Typically, the time limit for a 100K will be around 16-18 hrs, so it's just a super-long day. 100 mile time limits are usually more like 30-48 hrs depending on the race difficulty. You still probably wouldn't sleep at all or maybe for a few minutes. For longer races you have to sleep some, but people typically try not to sleep for very long because when you're sleeping you're not moving.

What do you eat? #

For shorter races, people typically eat the same stuff you'd eat in a marathon: energy bars, gels, sports drinks, etc. For longer races, people often want real food of some kind or another whether it's snacks like (cookies, chips, pretzels, etc.) or even something more substantial like quesadillas, pizza, etc. Typically as it gets dark and cold, aid stations will serve soup or broth, as well as coffee.

Do you have to carry all your food? #

Most races will have "aid stations" along the way. These are usually tents with food, water, and some electrolyte drink (high-tech Gatorade, effectively). The aid stations may be anywhere from every 5 miles to every 15-20 miles apart. Even on a race with frequent aid stations, many runners are moving quite slowly (14 minutes a mile is a very respectable time for a 100 miler), so there can be quite a bit of time between aid stations and so most people will at least carry some kind of fluid with them especially on longer races where you might be running through the hottest part of the day. Also, if there's some food you particularly like you might carry this. If I don't like the electrolyte drink they are serving I might bring my own, though it can be a pain to mix at the aid station.

A lot of races will also have "drop bags" which you can give to the organizers at the start and they will take to the aid station for you. These can contain food, clothes, a headlamp, whatever (you don't really want to carry your headlamp all day, right?. Some races also allow you to have a "crew" which is to say people who meet you at the aid station to assist you, bring you food, etc.

Seems like you're not going very fast. #

That's right. Speed drops off pretty fast the longer you go and the more climbing there is, the slower the race will be overall. In fact, most people will "power hike" any significant climb: running uphill is very tiring and isn't that much faster than hiking. In addition, if the trail is technical that slows you down as well, as does running in the dark. Finally, if the race is at altitude, that will also slow you down.

Why would you do this? #

I am unable to provide a satisfactory answer to this question.


  1. I've seen a number of American ultras which are 100.2, presumably in imitation of the famous Western States course. ↩︎

  2. I did this back when it was a 50 miler and they are not lying when they say it is rocky. ↩︎

  3. My coach, Emily (Harrison) Torrence, has won JFK race twice. ↩︎

  4. This mirrors the terrain differences between the Pacific Crest Trail and the Appalachian trail ↩︎


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