Ultra-Marathon Trail Run Race Day Deconstructed

What is it like to run 100km?
trail running

Ultra-marathon trail running. What is it like to run 100km or further? There is a growing movement of people looking to push their body past the humble road marathon. Choosing instead to add in longer distances, mountainous terrain and outdoor survival to the pain party. Endless advice and online chatter is available for training, comparing shoe choice, watch features, nutrition supplements and other ultra gear. But what is it actually like to run 100km?

Following the marathon race-day deconstructed article, I’ve broken down the 100km ultra-marathon to for p to challenge themselves with this event. They say it helps to visualise the day so I hope this helps! For those that have had the pleasure already, I am interested in how this compares to your experience as everyone’s experience will be different. Lastly, I’m not a professional runner or coach so any advice here is based only on my experience. And, a few quips from the experts…

“It hurts up to a point, then it doesn’t get any worse”. - Ann Transon

Ann Transon is a 14 time winner of the Western States 100 and known as one of the toughest competitors in trail running.

Section I: 0-20km

The gun goes off! Hundreds of brightly coloured, carb-loaded and well-trained athletes bustle for position on the trail. All the lead up niggles and logistical issues fade away. Just lots (and lots) of running ahead.

Trail congestion

Large trail runs employ wave starts to ensure a slow release of runners and prevent trail congestion. For the first 5-10km slow runners will appear in front and faster runners will come up behind. This can easily mess with your own pace as you dart past those in front and feel pressure to run quicker from those behind. Best to communicate with other runners to let them know when you’re passing and when they can pass you to avoid stumbles and falls. At this point of the race you don’t want to come THAT close to the trail.


Sipping water/electrolytes at regular intervals is of course important. Over hydration though can lead to  issues. Sipping, similar to you would in training, is all you need as you can’t build up long term stores of fluid, it will just flush your system of essential salts needed for the body to function. Just ensure you have your food and drink for this first section close to hand. That way you can access it regularly when you need it without under or over hydrating.

Early pace

The first section is a feeling out phase. A good measure of exertion at this point is sweat. It will be early, likely in the mountains, so relatively cool. Your pace should be slow and steady so if you are sweating profusely or gasping for breath, this is a sign of potential burnout. Back off the pace until you compose yourself. If you use a heart rate monitor, try focusing on your ‘cruising’ heart rate (for me it’s below 150 bpm) and use this as your key indicator early on rather than time or speed at this stage of the event.

Before you know it, Checkpoint 1 will be upon you! Yay!

“Run for 20 minutes and you’ll feel better. Run another 20 and you might tire. Add on 3 hours and you’ll hurt, but keep going and you’ll see, hear, smell and taste the world with a vividness that will make your former life seem pale.” – Scott Jurek

Scott Jurek won almost everything there was to win in trail running from 2000-2010. He recently completed the 3,500km Appalachian Trail in a record 46 days.

Section II: 20-40km

Bag drops

Another logistical challenge in these events is checkpoint bag drops. Usually a bag can be made up for each checkpoint to replenish your supplies and gear (e.g. socks!). An alternative is have your friends and family act as a support crew and bring everything you need. It is personal preference, but it pays to be self-sufficient as much as possible.

Support crews

A support crew, in some events, is the only way a runner could possibly complete it. Where an event allows bag drops and the runner to be self-sufficient, plan for that. As great as it is to have a support crew, relying on them for everything critical to you completing your race is risky. It is tough as a spectator to navigate around remote and territory and be at the right point at the right time. You know what you want, when you want it and how you want it done. And, this may change during the event based on how you feel. A support crew’s value is seeing a familiar face as you stagger out of the wilderness. This will be 100 times more valuable than anything else they can do for you on course.


Checkpoints are offical time and gear checking stations and for topping up supplies and making any critical gear changes. Soaking up the atmosphere of the event is also an important mental refresher. Don’t dawdle though! You can easily spend over half an hour or longer of your entire race in checkpoints. That’s a lot of extra time to be on your feet. I was shocked when I saw the time I spent in checkpoints at the end of a race. On average I had spent 5-6 minutes compared with the winner who sailed through in less than 1:30 on average!

Ultimately, checkpoints become bookends to successive half marathons that just get harder and harder to pull yourself through. They become the mental reward and a physical refresher that punctuates your journey to the finish.

“I have found my church, and it is at the end of a long trail on a distant mountaintop. It is there that I feel most at peace, entirely content and whole.” – Dean Karnazes

Dean Karnazes, the ultra-marathon man. Ran 50 marathons in 50 US states in 50 days then ran home to San Francisco from New York as a warm down run.

Section III: 40-60km


Somewhere after the 40km mark your heart begins pumping what feels like lead instead of blood around your body.  And, it all feels like it’s accumulating in your legs. Your legs will feel like bulging weights that your body needs to wrestle with to maintain a forward motion. Till now, even with 40km complete, it’s all still a feeling out phase. Everything starts to get real, real quick in this middle section.


By now you have likely recognised the high amount of walking undertaken in most ultra-marathons of 100km or more. While the elite runners may be able to run most of 100km course, us mere humans, like it or not, need to walk, a lot. Even if you achieve what is considered a respectable time, walking will form a major part of your race. Training for walking uphill is commonly recommended and a good idea. Keeping a military like pace with short powerful strides will serve you well. It also allows composure for essential eating and drinking while out on course.


On the subject of eating, the same conundrum exists as in the marathon. You need to be well hydrated to eat successfully yet eating can dehydrate you. Gels do a good job of maintaining a tick in both eating and hydration boxes. Newer products like Tailwind aim to combine nutrition and hydration with some success. At one point or another though something of substance needs to get in your belly. Think 2-minute noodles or other easy to digest material yet made up of long burning carbs, ideally washed down with a nice salty watery broth. Yummo!

Celebrate small wins

Nearing the 60km mark you are likely to be reaching the upper limits of your longest training run distances. If this is your first 100km event, you are reaching the furthest you have run in one go ever! Well done you! And, here is the 60km checkpoint now. That lead in your legs just let go for a second and you even managed a high five with the volunteer on the way into the checkpoint. Nice one!

Only recently have we come up with the technology to turn lazing around into a way of life. We've taken our sinewy, durable, hunter-gatherer bodies and plunked them into an artificial world of leisure. - Christopher McDougall

A runner from the Tarahumara tribe of northern Mexico renown for their exceptional running ability and the focus of the bestselling book Born to Run by Christopher McDougall.

Section IV: 60km – 80km

Dire straits

60km checkpoints tend to be pretty dire places to observe as a spectator. As a runner you won’t notice so much the other runners as you’ll be dealing with your own demons. Runners are on every degree of the pain spectrum. They range from energised, game-face-still-on style runners to broken people with gigantic blisters and gashes from fatigued falls and those shivering under a space blanket. Then there are the quiet, solemn runners which you can tell are pondering that, while they are over half way, there is still a very tough marathon to go. The sun is getting a little lower, the fun has faded and their wondering whether they can endure this any more. Again, why checkpoints are best to get in and out of quickly.

Mandatory gear

A lot is spoken about in the lead up to ultra-marathon trail events around the mandatory gear runners must carry to ensure safety and survival in the wilderness. All items are important to have and it adds to the burden of this beast of an event.  Cutting weight is a very common lead-up task involving cramming all mandatory items into a pack one-third of the size that is comfortably needed.

Remember, there may be occasions during the event where a piece of your gear is actually needed or needs to be shown to course officials. If this is gear is vacuum-packed into your backpack, you’ll have a hard time getting it out and an even harder time getting it back in. Particularly in the dark with freezing fingers and the mental capacity of a goldfish! So, pack tightly but also wisely so you can access your gear easily and have a system for where it all goes back in. The majority of weight you carry will be water anyway, so time your water levels to run out just prior to the next checkpoint or water stop.

Running downhill

Downhill running, as it turns out, is, at this point in the race, almost more painful than running uphill. You can never do enough uphill walking and also downhill running in preparation for a 100km trail run. Having the strength and flexibility for maintaining a good downhill running stride will be the difference between a good and average time.

Bent legs used as suspension springs keeps a low centre of gravity giving better balance and allowing more speed rather than slamming on the breaks too often and skidding out of control. Your legs will burn but the better prepared you are the quicker they will recover. Squats and lunges will help but nothing is better preparation than running downhill with tired legs. So find a nice big hill near the end of your long runs and run down this a few times to get used to it.

Post sunset blues

Unless you are an elite runner, the sun would have set some time ago by now and you are guided only by the solitary beam of your head torch. You are likely in unfamiliar territory and almost certainly alone. The lights of the 80km checkpoint can’t come quick enough. You have most certainly convinced yourself that you’ll pull the pin at this checkpoint. It was a nice attempt, but this is far enough, you’ve convinced yourself you’ve nothing left to prove. You’ve found out you can be a pretty convincing person after 80km of running!

kilian jornet

Kílian Jornet, part trail runner, part mountaineer. Wins almost every trail event he enters and summited Everest on his own (twice) in world record time in 2017.

Section V: 80-100km

Dazed & delirious

Funny things happen at this the final checkpoint. Your good and sane intentions of quitting are still vivid in your mind but no one seems to be listening (the slurred speech isn’t helping). You take a seat, remove your back pack and take in some offered food. As you look for an official to advise of your withdrawal, delirium sets in as volunteers guide you back towards the course. You are walking like a new born foal as some fellow runners shuffle past and you get sucked in to their draft and before you know it you are back out in the darkness.

Zombie phase

You have reached the zombie phase of the ultra. Your body is contorted, you favour every aching point in your body yet still you slide forward. Unbeknownst to you, a grimace has fixed itself on your face like a grizzled sea-faring pirate. Tunnel-vision is all you have and you shuffle directionless, lurching towards glitters of suspended pink fluorescent tape highlighted by your headlamp. You leave your body for minutes at a time until a stumble on an erroneous tree root brings you back into the living world.

Walking vs running

Anything more inclined than flat causes you to walk now. Every effort is summoned to break back into a run. You actually may not end up running again. Some people have actually been able to walk an entire 100km and still finish within the cut-off. Each to their own, but getting back sooner rather than later should be the goal. Wandering the wilderness all night is the devils idea of fun.

Final push

It’s the final kilometre! Your cramping, jelly legs aren’t much use any more. If you have another gel you will likely throw up (if you haven’t already) and your pee looks more like coffee than that ideal straw colour people always bang on about. But hey, you’ve made it! Well almost. Race Directors are cruel and evil people, (but essential ambassadors for the sport!) they often save some of the worst for last. Still, at 1km to go you could walk barefoot through red hot coals and not feel any more pain.

The finish!

The finish line. You hear the crowd and see the floodlights turning night into day. Before you cross the line you will, I’m certain have a tear in your eye and a lump in your throat. This is your special time to celebrate and give yourself a sneaky pat on the back. Then wipe your eyes and put on a good front for the finish line and your supporters, who let’s face it have likely had a longer, harder day than your fully catered bush walk! Plus, they don’t get a medal for their efforts, so buy them a beer!

The final word

The last word on ultra-marathons is left to Lazarus Lake who is part psychologist part eccentric race director of the Barkley marathons.

“For all the talk of exploring human potential, and seeking our limits, ultra-runners tend to play it safe. They line up challenges they know they can finish and run them carefully within their limits. At the Barkley, success is about over-reaching our abilities and living to tell about it”. Lazarus Lake (Gary Cantrell)

Lazarus Lake (aka. Gary Cantrell) designed the Barkley marathons to ensure failure. More people have walked on the moon than completed the physical and mental torture of the invite-only Barkley Marathon.

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About The Author


Ever since venturing out the back gate into the bush as a kid, I've had a curiosity to escape and explore as often as I could. It's fair to say that my curiosity has continued to grow instead of fade as the years go on. It eventually came time to turn a few scribbled notes into some legible stories and travel tips for anyone with a similar curiosity as me.

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