So, you’re thinking about running a 100K race?
That’s some serious mileage we’re talking about—over 62 miles!
To put that into perspective, that’s more than two full marathons back-to-back. It’s also 49 more miles than a half marathon and the equivalent of running twenty 5Ks in a row.
So it’s if I say it’s a huge undertaking I’m not exaggerating.
But don’t get me wrong.
Running a 100K is possible with the right preparation and mindset.
Let me walk you through what it takes based on my experiences and what I’ve seen work for others.
The 100K Explained
Let’s get back to the basics.
One kilometer equals 0.621 miles. So if you multiply 0.621 by 100, you get 62.1 miles.
In other words, a 100k race will have you running 62.1 miles.
That’s a lot of miles.
Still not making any sense?
Let me put that number in perspective.
Running a 100k is the equivalent of running 49 miles more than a half marathon, 36 miles more than a marathon, and over 30 miles more than a 50K.
The race is also the equivalent of 20 5K and ten 10K.
Yes, imagine running twenty 5K races in a row.
That’s a lot.
How long does it Take to Run a 100K?
The 100K distance may take most runners around 10 to 15 hours to cross the finish line. This means spending a lot of time running through meal times, cruising in the dark, and spending a whole day on the trail.
If you’ve ever spent that much time on your feet, you know it’s not just about the miles; it’s about endurance, pacing, and mental toughness.
I remember my first ultra—around hour 10, I started questioning why on earth I was out there. But trust me, the feeling of crossing that finish line after such an intense journey is something you won’t forget.
Overall, a good 100k time is 09:09:35. If you’re wondering where I got that number, then know it’s the average 100K time across all ages and genders. A fast 100K time is anything within six hours.
Are You Ready for A 100K?
Before you jump into 100k training, you’ll want to first have a few ultra-distance races under your belt.
Increasing your training volume over time will grant your body enough to adapt. Jumping from 5K to 100k is the recipe for failure.
The longer the distance of the race, the more time your body will need to adapt to a higher load. There’s no way around it.
At the very least, have a few 50-mile or 80K races as your starting point. When you follow this recipe, you’ll have to add 20k. Yes, by no means a short distance, but it’s better than jumping from a shorter distance.
To ensure you’re making the right decision, it’d best to have completed these 50-mile races feeling pretty good.
Building Your Base
Before you start tackling ultras, make sure you’ve got a solid base.
I recommend focusing on running pain-free for at least 6-12 months before jumping into a race like this. I’ve seen too many runners rush the process and end up injured.
Your weekly training should include five runs, focusing on easy efforts that gradually increase in length.
Eventually, you’ll consistently run 18-20 miles for your long runs. Trust me, patience pays off.
Mental Preparation is Key
Running 100K isn’t just a physical challenge—it’s a mental game. I’ve had races where the physical pain was less of an issue than the mental hurdles I had to overcome. You’re going to hit low points, no question about it. But training your mind to keep going when your body wants to quit is crucial.
I remember hitting mile 40 in my first 100K, and every part of me wanted to quit. My legs felt like lead, and mentally, I was questioning why I’d signed up for this. But what got me through was focusing on small milestones—the next aid station, the next hill, the next mile. Breaking the race into smaller chunks made 62 miles feel less intimidating.
I know this sounds easier said then done, but believe me – once you train your mind as hard as you train your body – you’ll get my point.
Spend Time on Your Feet
More than anything else, you need to get used to spending hours on your feet. Your body has to adapt to spending hours and hours on your feet to withstand the challenge on race day.
I remember when I started upping my long runs, it wasn’t about speed; it was about time. You’ll want to incorporate long, slow runs into your weekly routine, gradually increasing the distance. Hiking is a great way to build endurance without the impact of running.
Aim to complete at least one 50K or longer run a few weeks out in the lead-up to your race. I’m a big fan of back-to-back long runs—this simulates running on tired legs, which is exactly what you’ll face in the later stages of a 100K.
Fueling is Everything
From personal experience, I can tell you what you eat, how much, and when can make or break your race. During my training runs, I experimented with various snacks and drinks.
Trust me, while some choices sent me zipping along the trails, others had me wishing for a roadside pickup! You’ll want to find that perfect mix of carbohydrates, sugars, and electrolytes to keep your engine running smoothly over those long miles.
Unlike shorter races where you might wing it on minimal fuel, a 100K demands a solid fueling plan. Begin by figuring out how many calories you burn per hour and how much fluid you lose. This isn’t just guesswork; use a formula to estimate your caloric needs and take a sweat test to gauge your hydration requirements. This information will be the cornerstone of your fueling strategy.
Here’s a starter list of things you might consider packing in your running belt:
- Fruits – Easy to digest and packed with natural sugars.
- Gummies and Energy Gels – Quick, convenient bursts of energy.
- Energy Bars – For a more substantial fuel source.
- Sports Drinks – These are essential, not just for hydration but also for their electrolyte content.
Finding the right combination is a bit of trial and error, but it’s worth the effort. What sits well in your stomach? What gives you a noticeable energy boost without causing a crash? Answering these questions through experimentation will guide you to your optimal race day fueling regimen.
Choosing Your First 100K
The right race can make or break your experience. For your first 100K, avoid anything with crazy elevation changes or extreme weather.
I’ve made the mistake of choosing races that were too challenging for my level, and it’s no fun having to drop out halfway because you weren’t prepared for the conditions. A DNF always sucks no matter the reasons.
I recommend choosing a relatively flat, well-supported event course in a comfortable climate and weather.
Leave things like heat, humidity, elevations, and hyenas for when you’re more experienced. That amazing race through the desert or the jungle or whatever will be there next year—and the year after that—no need to jump stages.
I’ve found websites like UltraSignup super helpful for finding races. You can search by location, distance, and difficulty, which is key when looking for something manageable for your first attempt.
Vertical Gain and Race Strategy:
Another factor to consider is the vertical gain of your race. I recommend choosing a course with limited vertical gain for those new to ultra distances. Vertical gain can be deceiving; a route with significant elevation changes will require different pacing and energy management strategies.
Using the ITRA’s kilometer effort conversion, for every 100 meters of elevation gain, it’s akin to running an extra flat kilometer in terms of effort and time. It’s like turning a 100K into a much longer race.
Learning this early on helped a first-time ultra runner I coached, Mark, choose a less demanding course for his debut, ensuring his initial ultra experience was challenging yet enjoyable.
Integrating Vertical Training:
Different terrains can significantly affect your pacing. Running through softer surfaces like mud or sand requires more energy, which can slow you down and extend your total race time.
If your race does involve hills, make sure to include hill workouts in your training. This could be specific hill repeats or incorporating hilly routes into your long runs. Not only does this build strength and endurance, but it also prepares your legs for the descending which can be surprisingly taxing.
Incorporating these elements into your training helps develop the necessary skills to manage them effectively during the race.
Think about it like this: if you’re running through trails with many loose rocks and roots, practicing on similar trails will help you learn to maintain your speed without tripping or getting injured.