Lacs de Fenêtre, certainly one of the most epic viewpoints along the road

What It’s Like Running A 100 km+ Ultramarathon

Daniel Issing
15 min readJul 28, 2018


The ins and outs of ultra running have become so familiar to me that it’s easy to forget how strange a world it is for those who never felt a temptation to run for hours on end, much less signed up for an actual race. Not that I find this astonishing: The grueling prospects of waking up on a Saturday morning at some unearthly hour, only to push your body through mud and snow, over icy mountain passes and through scorching valleys, do not let it appear as a very reasonable (not to mention pleasant) endeavor. This mental image is probably to blame for the fact that my running has become the number one conversation topic whenever I meet someone who knows about my exotic passion: How is that even possible? How do you prepare for it? What are you thinking about during all these hours on the trails? Is it more of a mental than a physical challenge? And, especially from well-meaning relatives: When are you finally going back to normal?

I’m far from being the first, the most experienced or most successful runner to write about these topics, and a simple Google search will probably turn up hundreds of results that tell variations of my story. I figured, however, that my own particular filter bubble is unlikely to come across any of these either by chance or on purpose, but would nevertheless enjoy reading about it.

The challenge

I’ve done long races in the past, most notably the Maxi Race around Lake Annecy (83 km) in 2017 and the Trail du Gypaète (72 km) last month, but never anything longer than 100 km. And sure enough, you don’t want to make things too easy on your first attempt, which is why I ended up selecting the X-Alpine Race in the Swiss Alps. In addition to being 111 km long, the X-Alpine is also one of the most mountainous courses in the world: Successful participants will have climbed and descended more than 8,400 vertical meters by the time they cross the finish line, going as high up as 2,800 m above sea level. The cumulative elevation gain is just a little bit below the height of K2, the world’s second-highest mountain, or about 6–8 times what you’d cover during a medium-to-difficult day hike in the mountains. The X-Alpine also stands out among similar races in that it has a lot of very technical sections, were running is not even an option. It may not come as a surprise that historically, only about 45% of starters finish it.

The preparation

So how do you actually get ready for such a challenge? Individual preferences will vary, but I think there are a few building blocks that can’t be ignored. Unsurprisingly, you’ll be spending a lot of time out running. Most experts recommend at least half a year of focused preparation for a person of average fitness, during which you gradually built up intensity. I’m running pretty much year-round, irrespective of weather conditions, and collect up to ~90 km during peak weeks (typically combined with shorter races). This translates to 12–14 h on the trails, a considerable drain on any weekend. If you think racing is hard, you haven’t looked at the training.

Preparation has to start early, so conditions for running aren’t always ideal (pictures from March)

I’m fortunate enough to live very close to the mountains, so I can easily simulate race conditions during my training. I tend to run 4–5 times a week, sometimes just for an hour, sometimes focusing on speed training (interval workouts), sometimes for half a day with my running vest, nutrition and emergency kits. The weeks before, I reduce my mileage significantly, to the point where my feet are itching to run again. Generally speaking, I don’t think there’s any magic behind it, but a lot of room to test and try what works well for you and what doesn’t — gear, food, training schedule (morning or evening?) etc. As I write these lines (two days before the event), I’d say that my preparation went well, but not perfectly, and whether or not my ankle plays along will be a crucial factor during the race.

The night before

Minutes before the start — still looking happy and fresh.

Looking at the data from past races, I estimated that it would take me around 24 h to finish, provided things went reasonably well. That being the case, you might want to get a good night of sleep before starting, but at least for me, that’s never how it works. Even though I pack all my gear the day before and try to go to bed early, I consider myself lucky if I can get my 2 — 4 hours of rest. Both your biorhythm and the excitement about the race are predestined to keep you awake, as your brain walks you through all imaginable sources of failure (what if my alarm doesn’t work?). As a result, by the time you’ll have to get up (typically around 2 am, as races tend to start at 4 or 5 am), you’ll wonder what on earth made you sign up for this. But now is not the time for philosophical contemplation, and you’ll better have some breakfast and put on the final touches on your equipment before heading to the start line.

The race

Photo by Sven Bass on Unsplash

Despite all initial sluggishness, the beginning of a race is usually among the finest moments of the challenge. Race managers know well how to create some hype before the pistol goes off: upbeat music, light shows, countdown — you get the idea. What’s fascinating is that in the midst of all this noise, you can still feel an aura of deep focus, as runners attempt to center their attention on the task ahead of them. When the wheels are finally set in motion, a throng of torches dispersing into the night, it’s hard to deny that there’s something almost spiritual about it. Apart from the occasional runner’s high (more on this later), you’ll probably never feel as good as this during the race. The air is still fresh, your legs aren’t tired yet, and you can look forward to witnessing a sunrise from a mountain peak. Knowing that the race will be long, you can take your time, and there’s no need wasting energy by trying to surpass other runners on narrow switchbacks. You’ll most definitely need those reserves later on.

Altitude profile of the course. There are seven peaks to climb, spanning from a couple of hundred meters of ascent to nearly 2,000 m.

If this won’t keep you going…

You might think of long-distance running as a battle between good and evil, where success depends on whether the former, on balance, prevails. The number one thing throwing its weight behind the benign forces is certainly the landscape. I really, really dislike running on flat, paved roads. By contrast, reaching a mountain peak after a long and exhausting climb, with a stunning view of the surrounding area is just that — breathtaking. Add thundering waterfalls, refreshing mountain streams, crystal-clear lakes and, with some luck, wildlife to the picture, and you’ll understand why this is such a captivating experience that makes me want to do things over and over again. Given that you’ll cover much longer distances than during a hike, the scenery tends to vary more extremely. Some say ultra races feel like life in a day, which is a nice, if too extreme, analogy.

High and higher

I know some people who run with the stated purpose of achieving a Runner’s High. It’s never been my central focus, but I find that it comes almost naturally during long runs. If you are so inclined, this is where to digress into mysticism; a feeling of being at one with nature, of transcending your physical body, but the basic sensation is simply one of being unstoppable. It really feels like you could run forever. Rather than your body or the trail imposing limits on your performance, it deludes you into believing that you are fully in charge of everything.

About 60 km into the race, shortly before reaching the Lac de Fenêtre (see above). I don’t remember if I was experiencing a runner’s high at this point, or just faking a smile for the photographer.

The bad news is that a runner’s high, while sometimes occurring multiple times during a race, is short-lived. I’ve seen people claiming periods of up to a half an hour, but 10–20 minutes seems more realistic to me. Ultra running would be truly miserable without these moments, but my optimistic estimate is that you’ll spend at most 5% of your race time in this state. On the bright side, even knowing that it won’t last long doesn’t seem to affect its positive impact, and in that, it’s quite different from, say, joyful anticipation.

Mind your body

People not acquainted with ultra running are likely to think that a race is mostly a fight against the physical limitations of your body. The truth is that bodily pain is often negligible, and the true battle is the mental one.

This is not to say that you won’t be going through a lot of physical suffering, too. But unless you’re suffering an acute injury, some sharp and sudden pain, I don’t think the kind of ‘wear and tear’ you’ll expect from running 100 km+ is going to stop you. Barring emergency situations, it’s unlikely that your legs are going to decide It’s Been Enough And We’re Tired and simply refuse their service. They will be heavy, but the effect levels off after a while. However, another part of you, your central governor, isn’t so gentle. From the empirical research,

“The marathon race provides evidence that human athletes race ‘in anticipation’ by setting a variable pace at the start, dependent in part on the environmental conditions and the expected difficulty of the course, with the capacity to increase that pace near the finish. Marathoners also finish such races without evidence for a catastrophic failure of homeostasis characterised by the development of a state of absolute fatigue in which all the available motor units in their active muscles are recruited. These findings are best explained by the action of a central (brain) neural control that regulates performance in the marathon ‘in anticipation’ specifically to prevent biological harm.”

Or, figuratively speaking, your brain will be constantly yelling at you to STOP THE MADNESS long before your activity reaches a point where it causes lasting harm to your body. This is no doubt a good thing, but it’s also the principal challenge in ultra running.

It’s obvious that at almost any point during the race, the end will be incredibly far away, and there’s no shortage of excuses and mental images your brain will evoke that make quitting seem like the only reasonable option. Yes, a sweet voice will tell you, you’ve already done a lot, more most other people will ever run in their life, so why not stop it here? Just take a little nap on that meadow, or get some food that doesn’t taste like some deliberately wanted to make you feel miserable? And that little mountain stream next to you, wouldn’t this be the ideal place to put your swollen feet in and relax a bit? The list goes on, but you get the idea. It takes tremendous mental effort to ignore all the bodily warning signals; to resist the temptation of stopping, and just keep going because…well, because goddamn signed up for it.

One of the many mountain streams we passed. Yes, it’s extremely tempting.

(One might think that it helps to remind yourself that it was your own choice, that you wanted to do this and no one is forcing you to be here. In my experience, the reverse seems true, and I sometimes wish I could be really mad at whoever made me do this, and view finishing the race as an act of defiance.)

Fortunately, some strategies exist do deal with this, although none of them is perfect. Setting intermediate goals in the form of peaks, aid stations, or even just the next tree, is one way to go about it. Another one is trying to really “live in the moment”, which works especially well on technical downhill sections that require your full attention. Picturing your arrival — whether in the form of a cheering crowd or a loved one waiting for you— vs the depressing feeling of having to wait for hours at an aid station until finally a bus will bring you back to the start can do wonders. If the terrain allows your mind to wander off a bit, a concrete problem that you want to think through can distract you from momentary pain, but I’m still struggling with this technique. If all else falls, sitting down for a little while to take a few deep breaths is an absolutely acceptable manœuvre .

Subjective distance

There’s one aspect of the above that is worth emphasizing. I imagine no one being astonished to hear that even splitting the race into various intermediate “finish lines” is only a partial remedy against Hofstadter’s Law: It always takes longer than you expect, even when you take into account Hofstadter’s Law. The time it takes to get to the next aid station feels much longer than it actually is, and the disheartening discovery that you’re barely halfway there when you thought it was just around the corner is a feature that’s as cruel as it is common. More interesting than this piece of conventional wisdom, however, is that it’s not just being overly optimistic about your pace, but that your perception itself is being fundamentally altered.

I mean it: It’s not just that you thought you reached a peak and turns out you were wrong, but that you absolutely cannot believe that yes, you’ve really only advanced a handful of kilometer when it totally felt like at least a half marathon. Sure enough, this gets worse if you’re sleep-deprived, it’s dark and you’ve already ran a long time. Some studies find that in particularly grueling races, at least a third of all participants experience hallucinations.

Fueling (or “What to eat and drink?”)

A typical aid station. There’s usually one for every 10 km, and trust me, they’re heaven on earth.

In short, I eat a lot of junk during the race. By that, I don’t necessarily just mean processed sports food (energy gels and the like), but more generally a combination of foods that I’d only consume in very moderate quantities under normal conditions. Of course, on races longer than a couple of hours, there’s no way around replenishing the calories you’re losing, but at the same time, you want to steer clear of food that’s too burdensome for your digestive system. What do you do?

Since this is not a post about the science of nutrition, I’ll avoid going to much into detail. Water, unsurprisingly, is your number one concern, and I always fill up my flasks before leaving the aid station to have at least a liter with me. I don’t have very good estimates of how much I drank, but more than 10l and less than 20l seems like a safe bet. Most of it is water, sometimes tea or sports drinks. Up next on the list would be carbohydrates, preferably in the form of glucose. You might imagine that ultra runner devour insane amounts of energy gels during races, but while individual preferences vary, I can’t conceive of an athlete fueling exclusively on gels. Instead, especially for a race as long as this, I’ll also rely on cookies, cereal bars, PB&Js, crackers, cake, pasta, chips…or more generally, a lot of junk food that doesn’t engage your stomach for too long and provides readily available energy.

Another key element are electrolytes, crucial to a host of body functions. It’s quite easy to enter a low-electrolyte regime during intense activity due to sweating and fluid intake, and this can result in permanent health damage. Gels or sports drinks supply some of them, as does a salty broth, one of my absolute favorites in long races. Finally, protein seems to help avoiding muscle breakdown, so I’ll also make sure to get my fair share of it. As a vegetarian, my choices are a little more limited here, but it’s never been a problem. Nuts, quinoa, chia seeds, bananas…do the job just fine, and you wouldn’t want to eat a steak during a run anyway.

The aftermath

I arrived at the finish line after 25 hours, and a weird arrival it was. I expected to feel some kind of extreme relief, a rush of pride over such an achievement, or just pure and simple joy, but nothing like that happened. In fact, running through Verbier (the final point of the race) felt like trespassing a ghost town. At 5 am, most spectators had obviously gone home already, the speakers were off, and the remaining volunteers were struggling to even fake interest in who was coming in. Not that I could blame them —and just to avoid misconceptions, I will say explicitly that all of them are, without exception, absolutely fantastic, genuinely friendly people who deserve nothing but praise for their selfless work — but the entire atmosphere really drained out all the enthusiasm in me. The good news is, as I’ve experienced in previous races, that it doesn’t have to be this way, and crossing the magic line can indeed be an extremely emotional moment.

How I imagined my finish would be like (from a past race).

Of course, the main challenge isn’t so much how long you’ll take, but that you’ll make it to the end. That being said, I’d lie if I claimed that I didn’t care about my time at all. For some perspective, this year’s winner, Jean-Philippe Tschumi, completed the race in just below 16 hours, a new track record — chapeau! Of the approximately 500 starters (out of which 266 finished), I came in at position 58, which is not too bad for a first attempt. I would have certainly hoped for an hour or two less on the trails, and I believe that would well be within reach should I give it another try next year. But then again, there are so many interesting courses out there that I’m not expecting to come back anytime soon.

Finally, how do body and mind recover after such a feat? (Disclaimer: Your experience will differ.) I’ve gone through quick and painless as well as somewhat agonizing recoveries, and this one was of the latter category. It might be surprising to hear that those parts of the body you’d expect to be most impaired — legs and knees — are actually just fine. Yes, there’s some muscle soreness that lasts for a couple of days , and makes walking a little hard in the immediate aftermath of a race, but it isn’t extremely bothersome. In fact, by Tuesday or Wednesday, I hardly felt much of a difference anymore. Pro tip: Massages, or, better yet, liberal use of the excruciating black roll, help a lot with this process.

The rest, however, didn’t go back to normal as smoothly as my legs, but recovered in phases:

  1. Post-race euphoria. There’s still a lot of adrenaline in your system, which seems very effective at temporarily blocking the onset of a fierce immune response. I feel asleep quickly and felt pretty OK when I woke up again after only four hours of rest.
  2. The day after. Tends to be “too good to be true”. I’m tired, but not exhausted, and (blisters aside) largely pain-free.
  3. The second night. Oh boy. I tried hard to eat something before going to bed when my stomach began revolting and made me throw up. I felt a lot better afterwards, but wasn’t able to replenish the storage I depleted during the race. I do not think I slept at all during the night, or if I did, it was in very short intervals, interrupted by violent headache, stomach cramps and a feeling of restlessness.
  4. Phase-out. I spent almost all of Monday in bed, waking up only to eat or read a bit. For the remainder of the week, I felt weak and somewhat worn out, sleeping a lot and still being very slow with just about any task I committed to. It took around 5–6 days to be alright again, which is also when I — veeery gently — resumed my training. (Science agrees that this the typical length of the recovery period.)

There is so much more that could be said, but I’ll end here as this post is already quite long. In particular, at no point did I talk about The Why. I feel this would be a topic for yet another article, and I’m happy to offer some introspection about what got me into ultra running, and why I decided to stick around, should there be enough interest.

Last but not least, here’s a nice teaser of the event that conveys much more powerfully what I tried to express above:



Daniel Issing

Book reviews, trail running, physics, and whatever else I feel like writing about.