6 Reasons You May DNF an Ultramarathon

Last Updated on November 19, 2020 by Heather Hart, ACSM EP, CSCS

If I’m an expert in anything regarding running ultramarathons, it’s how to successfully DNF them. Clearly I’m not ashamed to admit it.

My first ever ultra, which I had fully intended to be a 100 mile finish, ended at a very humbling 52 miles. And while I’ve successfully finished (and podiumed) countless ultras since then, there have been more than a handful of DNF’s logged onto my ultrasignup resume.

DNF’s, or “Did Not Finish“, can happen for a number of reasons. Some of them are unavoidable, such as a twisted ankle that leaves you unable to continue running. But other ways to DNF an ultramarathon are common and completely preventable.

Ultramarathon DNF Scare Tactics:

“Top 6 ways to DNF an Ultramarathon? Is this a guide on what NOT to do, or a guide on how to get out of a race you didn’t really want to run in the first place?” – my 12 year old.

When I was 13 years old, I attended a week long summer camp put on by the state of Vermont’s Fish & Wildlife Department. We learned very Vermont things, such as how to pack and load a muzzle loading shotgun, how to tie fly fishing flies, and that the kool-aid powder in an MRE can be eaten like Fun Dip candy. We also dove heavily into outdoor safety and wilderness first aid.

Forever burned into my memory from this experience was an education survival film we watched one night. In it, the protagonists of each scenario presented got themselves into some sort of backcountry pickle, and died a tragic – yet preventable death.

Their death was drawn out in classic 1980’s dramatic cinematography, designed to scare you into not making that mistake yourself. It was actually kind of traumatic on my young teenage brain – but it certainly did the trick. I will never drive into the desert for a joy ride with my friends without water, that’s for sure.

The point of this story is to demonstrate the same approach I’m taking to this blog post. I’m going to scare you with all of the things you COULD do wrong, so hopefully you don’t do them. (Sorry, you’ve got to provide your own MRE issued Fun-Dip).

6 Ways to DNF an Ultramarathon

Every single one of these DNF approaches have been thoroughly tested by yours truly. That’s right, I’ve DNF’d multiple ultramarathons in my time due to the following reasons. I’ve seen countless other runners DNF an ultramarathon due to these reasons. Trust me when I tell you, these are a recipe for disaster. Avoid at all costs.

1. Start Out Too Fast

Starting your ultramarathon at a pace meant for a much shorter distance is the perfect way to ensure a DNF.

My 5K racing approach looks a little something like this: take off out of the starting line like a bat out of hell. Run HARD for the first 1.5 miles. Realize you went out way too fast, regret your decision, and spend the next 1.6 miles trying your best to hang on and not puke or pass out before you get to the finish line.

Spoiler alert: this approach doesn’t work well for ultramarathons.

Now, I don’t necessarily mean sprinting off of the starting line, I think we all know not to do that in an ultra. But rather, pushing a pace way too aggressive based on your training, ability, and race goals. If you blow all of your energy in the first two hours of a 10 hour event, you’re likely going to be incredibly miserable for the remainder of the race – if you even have the physical means to keep going.

What To Do Instead:

Develop the discipline to ignore what other runners are doing around you, and follow YOUR race day plan. Which let’s be honest, is easier said than done. So if you need to: try some more extreme measures.

• Set an alarm on your GPS watch to beep at you if you are pushing a pace faster than you should early on in the race.
• Enlist the help of a running buddy who is racing as well, and intends to stick with the same pace. Hold each other accountable.
• A friend and fellow runner once gave me the wise advice of heading to the port-a-potty at the very start of the race, once the gun goes off. Let the crowd go ahead of you, so that you aren’t tempted to try and “race” anyone right out of the gate.

2. Let Your Nutrition Slip

I initially wanted to title this section “Bomb your Nutrition” but changed my mind. Because here’s the thing: most ultrarunners know the importance of nutrition, and aren’t going to brush it off from the start. What happens, instead, is that nutrition plans begin to slip in the later stages of a race.

Picture this: you’re 45 miles into your 100 miler. Your stomach isn’t feeling 100%, and suddenly the idea of another sip of Tailwind or slamming down a gel makes you gag. So what do you do? You convince yourself you’ll be fine if you skip fueling for a little while.

Or, how about this scenario: you’re 80 miles into your race. It’s nighttime, and you’re a walking zombie. You think about your nutrition – when is the last time you ate? Was it an hour ago? Two hours ago? Time is kind of blurring together. You think about stopping to grab something out of the back pocket of your hydration pack…but man that sounds exhausting. Maybe you’ll just wait until the next aid station, it can’t be much further…

These scenarios, my friends, can lead to disaster. (Picture the Gob Bluth “I’ve made a huge mistake” GIF)

What To Do Instead:

Falling behind on your nutrition can lead to the notorious “bonk”. And once you hit the glycogen low, it’s often very hard to come back from. So, when your stomach is pissed off and the thought of another GU or PB& J makes you sick: try to eat something else.

Related post: Fueling for an Ultramarathon – a Complete Race Day Guide

Sometimes, simply switching from something sweet to something salty, or something liquid to something solid, can be a game changer as far as gastrointestinal distress. Or, try a different approach to your caloric needs. Can’t stomach 200 calories at the top of the hour, like originally planned? Try munching on something intermittently over the hour instead, until your stomach settles.

In short:

• Have a nutrition plan (calories per hour, etc.).
• Set an alarm or some kind of alert to make sure you don’t skip a nutrition interval.
• Make sure your nutrition is always easily and readily accessible.
• Have a backup nutrition plan, incase your stomach revolts, that still ensures you are fueling adequately.
• Know that you can work through nausea and an angry GI system.

3. Dehydration (or Overhydration)

All of the scenarios mentioned above with nutrition can happen to your hydration as well. Maybe during your race its:

• Super hot outside and you don’t drink enough water.
• Super hot outside so you throw back gallons of water, without keeping electrolytes in mind (hello hyponatremia!)
• Freezing cold, so sipping on water is the last thing on your mind.
• The middle of the night, you’re tired, and forget to drink.

You get the idea. But water – and electrolytes – are imperative for maintain normal bodily functions necessary to get you to the finish line.

What To Do Instead:

Much like the nutrition portion of this post, the best way to avoid dehydration or overhydration is to have a hydration and electrolyte intake plan. Obviously, this plan may change on the fly based on course conditions (perhaps it’s really hot during the day and cold at night, so your sweat rate changes). But being aware of your hydration status – and how it affects your body – is important.

Signs of dehydration include:

• feeling thirsty
• dark yellow and strong-smelling urine
• infrequent urination
• feeling dizzy or lightheaded
• exhaustion
•  dry mouth, lips and eyes.

Signs of overhydration include:

• confusion or cloudy thinking
• nausea and vomiting
• muscle weakness
• spasms or cramps
• headaches

4. Ignore Your Feet

During an ultramarathon, your feet can be your number one teammate that help you get to the finish line – or your worst enemy that results in your downfall. I’ve done a lot of painful things in my lifetime, from birthing children, to breaking bones, to having abdominal surgery (twice). But the pain of the skin on your forefoot splitting 90 miles into a race, or a blister that’s been aggravated over a 100,000 steps or more is like none other. It can quite literally bring you to your knees.

I’ve also seen the effects of other athletes who chose to ignore their feet during a race until it was too late. Lost toenails, blood blisters the size of half dollars, the pitted skin of trench foot (definitely do not google that one) – it’s gnarly. You can’t beat cutoffs and reach finish lines when every step you take feels like a blazing hot poker is being shoved under your toenails.

What To Do Instead:

Taking care of your feet during an ultramarathon is worth the extra time, and should be a top priority.

Now that said, footcare is highly individual and can vary from race to race. I’ve seen people who can run 100 miles in the same pair of socks and shoes during one race, yet have to spend endless time at aid stations meticulously caring for their toes on a different course.

But the point is, it’s worth taking the time to keep your feet happy. Do not ignore a hot spot, hoping it will go away. Spoiler alert: it won’t, and in fact will only get worse.

Not sure where to start? Check out the book “Fixing Your Feet” by John Vonhof (Amazon affiliate link). It’s worth the read, and the knowledge that will be tucked away in your brain until you need it.

Related post: I DNF’d My Race, Now What?

5. Caving to the Voices in Your Head

The mind is a powerful thing. It allows ordinary humans to conquer absolutely extraordinary feats. But unfortunately, it can also convince you that you are weak, and your time would be much better spent in bed rather than running a dark trail overnight.

I am no stranger to this phenomenon. Hell, those of you who have been around for a while might remember the time I quit a 100 mile race at mile 90, while in first place for females, not because I was injured or sick, but because I was tired, cranky, and decided I “just didn’t want to be out there anymore”.

Listen: chances are high that at some point during a very long ultramarathon, you are going to ask yourself “This was a really bad idea, why am I subjecting myself to this?” And in those moments, especially with the temptation of aid station chairs or your crew’s warm car, it can be really, really easy to sit down and say “I’m done”.

What To Do Instead:

I tell my clients that the best way to prepare for these “I want to quit” low moments is to acknowledge that your likely GOING to have them. I know that seems to be counterintuitive to the hardened, beast mode, “never quit” type of mindset we’re accustomed to seeing. But acknowledging that you’re going to have really low emotional moments gives you power – because it gives you a chance to come up with a plan to defeat them.

When you find yourself in an emotional low during your ultramarathon:

• Acknowledge it. “I’m having a low moment. This is normal. I knew this could happen.”
• Attack it.
  • Do you need calories?
  • Caffeine?
  • Distractions – tell your pacer you’re in a low so they can talk to (at?) you. Sing to yourself. Listen to music. You get the idea.
• Repeat to yourself that this low WILL pass – but only if you keep moving forward.

6. Showing Up Un / Underprepared

I feel like this section is so obvious, that I almost didn’t include it. But, I’ll put my coaching hat on and say it anyway: you’ve got to train for your ultramarathon.

Of course, this isn’t always a deal breaker – I’ve seen runners finish races that they were woefully underprepared for. But, it’s definitely worth mentioning that a surefire way to hopping on the DNF train is to show up:

Undertrained

You didn’t properly train for the race. It happens. I’m not here to judge you. But there’s no denying it: being under trained definitely makes reaching the finish line significantly harder.

Lacking Experience

You’ve trained for the race, but you’ve never actually experienced running past, say, 50 miles before. Or you haven’t run overnight before. And now you’re wandering through the dark woods, at 4 am, on 80 mile legs, absolutely exhausted, and unsure of this new territory. The lack of experience here can hurt.

Unprepared for Course Specifics

A generic 100 mile training plan (like the one I wrote) will get you to the finish line of a beginner friendly 100 miler. Will it get you to the finish line of Hardrock? Not likely.

What to Do Instead:

Train for your race! Train thoroughly, train for course specifics, and train in a way that you gain knowledge and experience that will help you on race day. I know this may seem obvious, but it’s definitely worth repeating.

Choose your own DNF Adventure!

Of course there are countless other reasons why you may end up DNFing. You could get lost (been there), you could show up undertrained (done that), or it could end up randomly snowing in South Carolina and the trail turns into a muddy slip and slide (checked that off my list). But, like the saying goes, if you fail to prepare, you prepare to fail. And hopefully preparing for these well known ways to DNF an ultramarathon will help you successfully make it to the finish line.