Over the last handful of years, the ultra marathoning community has seen a big shift away from the 50 mile distance to the more globally recognized 100k, roughly 62 miles. We saw America’s most historic and revered 100 miler, the Western States Endurance Run, remove all 50 milers from their list of qualifying races.
The 100k is the new proving ground for 100 mile preparedness.
The 100k distance rests in a nice sweet spot for many ultrarunners; it’s long enough to serve as a wild challenge, but the majority of the runners will be done by nightfall, back at the campfire or hotel for dinner. That said, the 100k brings its own unique set of challenges and is long enough that it requires a high level of fitness and mental toughness.
So don’t compare this to a 100 miler and get caught up in thinking that this is “just a 100k.” It’s a beast of a race, no doubt about it.
I commend you for taking on this challenge and will do my best to provide you with solid information and training plans that will get you to the finish line, accomplishing something that most people could only dream about.
Using a Free 100K Ultra Training Plan vs Hiring a Coach
So why use a free training plan instead of hiring a coach? Well, first of all, by all means, if you can shell out hundreds of dollars a month to have a living legend like Jeff Browning, Stephanie Howe, or Jason Schlarb coach you, go for it!
They can write plans, give you feedback and hold your hand through the ups and downs of training, but make sure to consider the following:
One, some people just don’t like the pressure of having a coach! I fall in this camp. For me, it felt like added stress, like I had to impress the coach or show them how hard I was working, which translated into a net negative experience.
I’ve always thought that a self-coached runner can likely achieve about 95% of their full potential on their own. A coach is probably needed to obtain those final few percentages, so I recommend maximizing what you can do on your own, and once you feel like you’ve accomplished that, then consider paying for a coach.
Second, I think there’s real value in being in control of your own training, learning what works, tweaking your workouts, and not relying 100% on somebody else.
The training plans I’ll provide will give you an excellent framework, and maybe you’ll follow yours to the letter all the way through, but most likely you’ll need to make adjustments on the fly, and that process of critical thinking and adaptation is going to serve you well in this training cycle and all your future running endeavors.
Am I Ready to Run a 100K Ultramarathon?
Before we go any further, we have to have a little chat about whether or not you should be walking down this 100k road, at this moment in time. With the training plan lengths I will provide here: 12 weeks, 18 weeks, and 20 weeks, you’re going to need to have a fairly significant running base and background.
I’m not saying that you can’t come off the couch, starting essentially from scratch, and go on to complete a 100k with 20 weeks training, but honestly, the risk of injury is so high that I’m going to advise against this in almost all circumstances.
So where should you be with your fitness and experience before taking on a 100k race? I recommend completing at least one trail marathon or 50k race within the preceding six months, on a course that has similar elevation gain per mile as the 100k course that you are contemplating running.
A big adventure run can substitute here,, but it should’ve been substantially longer/tougher than your average weekend long run. Think Grand Canyon Rim to Rim or Mount Hood’s Timberline Trail or New Hampshire’s Presidential Traverse.
You should also have a significant base of running with many months of consistent running, mostly to help avoid injury. From my experience, it takes many months of running to harden up your injury prone areas of the body.
When I first got into ultra running, I suffered many lower leg and foot injuries, but then after I worked through those, it was as if my body adapted to the stress, developed some resilience, and I went on to not have any significant injuries for many years.
That said, there’s some wiggle room here. If you can craft a narrative that makes you feel confident in your ability to jump right in and tackle a 100k without much experience, then don’t let me stop you! Bigger the risk, bigger the reward, right? Just know going in that that’s exactly what it is, a risk.
How long does it take to train for a 100K?
Everybody has their sweet spot when it comes to training plan durations. Personally, I like 18 week plans. It’s long enough to get in really great shape but not so long that the race feels like an eternity away and doesn’t create any sense of urgency.
It also depends on fitness level. If you just crushed a marathon or 50k, maybe the 12 week plan is plenty of time to make the physical and mental transition to longer sessions and bigger weekly time-on-feet volume.
Lastly, experience and comfort on trails matter. If you want to run a 100k in a mountainous environment with lots of beautiful scenic vistas, I recommend acquiring some experience on similar terrain.
Acclimating to high altitude, learning how to run efficiently on technical trails, experimenting with gear like hydration packs and trekking poles, finding trail shoes that work for you, and learning the ins and outs of fueling your body during long efforts; all these processes take time and ideally won’t need to be rushed.
With these types of considerations circulating in our minds, I’d say if you’re starting from scratch, you’re going to want to commit to 6 months of steady consistent running, do a trail marathon or 50k race, and then jump into one of the 100k plans I provide here.
Choose Your Goal 100k Ultra Race and Work Backwards
Alright, now that you’ve decided that 100k is within a rational realm of possibility, it’s time to select a race. This is both one of the most fun and important decisions you’ll make. What lights your fire? What type of experience are you craving?
Do you want something in your own backyard that will further connect you to your local or regional landscape, or is this a bucket list international travel opportunity? Do you want buttery smooth singletrack or technical rugged terrain that keeps you on your toes?
Does high altitude or afternoon lighting storms scare you, like enough to make things not fun at all? Then maybe don’t select a race in Colorado.
What are your local conditions like? Flat? Humid? If you live in West Texas with nothing but pancake flat, dusty, dry trails, I probably wouldn’t go run a 100k in Hawaii on a steep, rooty, muddy course with humid conditions. We want a challenge but we also want to be able to set ourselves up for success in training.
That said, you 100% need to be inspired by the objective. During training, I guarantee that there will be days when you don’t want to lace up the shoes and get out the door. It’s during those moments when you will need to dream about the event you are training for.
Whether you envision yourself on a mountain ridge in the middle of a vast wilderness or baking under intense heat with nothing but the shade of the occasional saguaro cactus to ease your suffering, whatever makes you excited and feel alive, the race should have those elements.
Our Free 100k Training Plans (PDF Printables)
12 Week 100k Training Plan
It’s crunch time! Full disclosure: I generally don’t recommend a 12 week plan. It can be done, and done well, but you can really only implement a couple cycles of intense training while including enough rest/down weeks to adequately recover.
But if this is what you want to do, I get it, I’ve done it, and if you hit it hard and find the sweet spot, without any major setbacks, you can get very fit and stay mentally sharp because of the shorter total training duration. Hold on to your hat, find your flow, and enjoy the ride!
18 Week 100k Training Plan
With 18 weeks, we have a solid amount of time to work with. With this longer plan, you’ll feel the rise in training week to week but it’ll be gradual enough to not feel overwhelmed and the risk of injury will be lessened because your body will have more time to acclimate to the work-load.
We’ll do three cycles of 3-week builds followed by one week rest and finish with a nice long three week taper. Personally, this is my preferred training plan duration.
20 Week 100k Training Plan
If you’re coming out of winter hibernation or your starting point is not where you’d like it, I definitely recommend this plan. Twenty weeks is as long as I like to go with a formal training plan. Anything longer than that, I’d just be prescribing base building mileage with very little structure anyways.
Here, we’ll be able to fit in four build/rest cycles where we increase your volume for two to three weeks and then take a recovery week to absorb the training. The additional benefit of a longer training plan is that it minimizes the detrimental effect of losing a week here and there to illness or minor injury.
The Workouts & Terms to Know
Base building runs:
These easy effort runs are the foundation of the plan. Not mentally or physically taxing but super important for building general fitness and promoting recovery from other more intense sessions.
Hill and speedwork:
Feel the burn! Here is where we test the upper limits of your engine’s potential. How high can we make that heart rate go? There are endless variations of this type of interval training and I do my best to keep things new and exciting for each and every workout.
If there’s a 100k race simulation, this is it! The long run is exactly as it sounds: big day out, lots of simple time on feet without any real agenda as far as pace or effort are concerned. This is where you dial in your nutrition and gear and get your body comfortable with discomfort.
Back to back long runs:
This is where we turn lemons into lemonade. Two long runs, one per day, but on consecutive days. On day two, we can really simulate what it’ll feel like during the latter stages of a 100k race.
The ability to run on tired, sore legs is sort of the name of the game in this crazy sport, so manufacturing these “opportunities” will be key.
No planned workout. This doesn’t mean you have to veg out on the couch all day. If you feel like biking to the farmer’s market or walking your dog to the park, by all means, maintain your active lifestyle, but nothing vigorous.
Rest means rest. It is just as important as any workout you do. Your body needs to recover so it can continue to do the on-going work required.
During some workouts, you’ll have periods of rest. Ideally, you aren’t standing completely stationary, but instead, jogging or walking to keep the blood flowing, flushing out the legs.
Even if you think you’ll be done with daylight to spare, I recommend that everybody go through the motions and develop some comfort running at night by headlamp.
Following a circular patch of light can be a disorienting experience so it’s not something you want to be experiencing for the first time on race day.
This is a solid steady effort, faster than your easy run days, but not all out. Think roughly 70-75% of maximum effort. You should be breathing hard and not able to have much of a conversation.
Make sure to start out at a pace that feels sustainable for the entire duration. You’ll get better at finding your red line with this style of workout.
Strength / cross training:
As we’re building up to full running volume, I like to integrate a fair amount of strength and cross training days. These allow you to build fitness but avoid the pounding and stress on your body from consecutive days of running. Choose either/or, strength or cross training.
If you like hitting the gym, I recommend focusing on running related exercises: hip and glute work, feet and ankle stability, quad/hamstring/calf strength. For cross training, choose your own adventure for 30-90 minutes: anything that gets the blood pumping and the sweat flowing!
Look for a place where you can run 100 meters or roughly the length of a football field. Start out with a slow jog and then increase your pace about every 10 meters until you’re running at about 90-95% of your maximum speed, then slowly wind it back down for the final 20 meters or so.
Think about smooth, efficient leg and arm swing, not straining. Fast but flowy.
Time on your feet:
If we’re going to ask our bodies to run/jog/hike/walk somewhere between 10-18 hours to cover 100 kilometers, we need to get used to being on our feet for long periods of time. Primarily, this will be done during long runs, but I also encourage this in your day-to-day habits.
Use a stand-up desk at work, walk the mile to the post office instead of driving, take the stairs instead of the elevator; these little choices add up and help keep the engine burning throughout your day.
Typically, the taper phase is the final two to three weeks of training before race day. This is a very important period of time where we take our foot off the gas, gradually decrease both the volume and intensity of training, so that the body begins to recover and freshen up so that you’re feeling ready to tackle the race.
Beware: it’s not uncommon to feel heavy or “off” during this period. In fact, expect it. It’s mostly psychological, but trust me, if you taper correctly, those feelings will disappear on race day and you’ll be ready to perform at your peak ability.
My Advice For First Time 100k Runners / Beginners
Learning how to pace yourself is going to be key to getting through your first 100k. It’s so easy to get carried away and end up overdoing it during the first half of the race.
It’s sneaky in that you might not feel like you’re working hard at all, but really it’s just the adrenaline and recent taper in your training that is making you feel light and snappy.
I actually try to avoid running with other people early on in ultras because it’s too easy to fall into their pace and rhythm, when you should be listening to your body and monitoring your effort indicators that you learned in training.
If you need a rule of thumb for a desired effort level in your first 100k, for the first half of the race, try to find what you would consider to be a very comfortable and sustainable long run pace, and then dial it back an extra 10%.
Another good idea, if your particular race offers this feature, is to join the early wave start. Sometimes races have a start time that is at least an hour before the normal start.
This will give you a chance to tick off some leisurely early morning miles and have a little bit more daylight at the end of the day when darkness can feel a bit scarier.
Another piece of advice is to eat early and eat often. The last thing you want to do is get into a major calorie deficit. I aim for a minimum of 200 calories per hour of racing. I usually start with 100 calorie gel packets and try to eat two of those an hour until I absolutely can’t stand them anymore.
I’ll then switch to powder calories that I mix into my water bottles. I’ll also graze on whatever foods look appetizing at the aid stations, typically fruits throughout the day and then soups at night once the core body temperature has gone down.
Lastly, I recommend writing down your worst case scenarios into a journal and plan out what you’ll do if any of them come to fruition. If you’ve contemplated it beforehand, then whatever happens out there won’t come quite as much as a surprise and you should be able to manage it better.
What will you do if you can’t get any calories down? What’s your plan if your old ankle injury flares up and you’re limping along at mile 40? What’s your plan if you feel like you may have accidentally taken a wrong turn and you haven’t seen a flag marker in awhile.
What are you going to tell yourself if you start feeling like you want to drop out at the next aid station? Under what specific circumstances will you and your crew allow that to happen? Work these questions out beforehand by putting pen to paper and you’ll be ready to take any surprises in stride.
My Thoughts on Weekly Mileage for 100K Training
For the 100k distance, I like my athletes to at least cover the distance and elevation gain of their particular race during one week of training. It will likely be your biggest week during the entire buildup.
So if you’re running 100k on a race course with 8,000 feet of vertical gain, then I’d prescribe roughly a 60 mile week and recommend that you try to piece together 8,000 feet of vertical gain during the week.
You can track your elevation gain on Strava, an app for your smartphone that allows you to record your runs utilizing the phone’s GPS. One click of a button and you’ll have more data about your run than you’ll ever need!
With 62 miles as the maximum weekly mileage, then you can expect to spend of the bulk of your training early on in the 30-40 mile range, the middle weeks closer to 40-50, and then you’ll peak out during the 3-6 weeks prior to the race at 50-60 miles a week, and then we’ll progressively taper down your volume to a very light race week.
Again, the trick is to get you as fit as possible without getting injured. Injury is the absolute worst-case scenario. As the old saying goes, it’s better to be 10% undertrained than 1% overtrained.
What I did was write plans that will work for the largest majority of runners. It can’t be tailor-made for everyone. Some people thrive off lots of miles, some people off less. Quality over quantity, and vice versa.
Every ultramarathon training cycle you complete will be another stone laid on your path to self-discovery and improvement. Pay attention along the way and then be sure to integrate the lessons learned into your next 100k attempt.
Race Day FAQs:
What is a good 100K time?
Any time under the cut-off! Did you know races have cut-off times where if you don’t arrive at specific aid stations within a set amount of time, they’ll actually stop you from continuing? It’s brutal! But also essential for the safety of the runners and out of respect for the time of the volunteers that run the aid stations.
The 100k distance can be run in as little as 6:05:41, which is Alexsandr Sorokin’s world record on a track, to 20+ hours for a back-of-the-packer on one of the hardest mountain courses in the world.
A good time is almost entirely subjective. Did you feel like you did your best out there? Did you run a time that your training indicated you were capable of? I’d encourage you to not worry too much about time, especially if it’s the first time running a particular course.
If, however, you ran this same course last year, and the course remained identical, then you can maybe think about beating your prior year’s time or something like that. I’d much prefer, though, that you evaluate your performance based on perceived effort and the grit and determination you exuded throughout the race.
How hard is a 100k race?
It’s as hard as you make it. For example, I could do a bunch of training, get really fit, and then go do a 100k race and stay somewhat comfortable for almost the entire thing.
However, if my goal was to get out there and push my limits and fight for every second on the clock, then that same 100k race could be one of the toughest experiences of my life.
No matter how you slice it, 100k is a very long way to carry the human body. The physical and mental toll is not to be underestimated.
You will be thankful for every extra ounce of effort to make in training because it’ll mean you’re going to suffer less on race day. Ultras are hard, they’re made even harder when trying to find your limits, easier if well-prepared.
What pace should I run for a 100K race?
Hopefully you were paying attention to some key pacing indicators throughout your training. I recommend going back and looking at what your pace was on your biggest long run, and then add on a minute or so per mile, and aim for that for at least the first 50k.
The unfortunate truth is that late in a 100k, you are most likely going to have some devastatingly slow miles. Plan on it and don’t let it shake you. You’ll bounce back and finish strong, making up for those earlier lapses.
If you are aiming for a particular time, it’s okay to calculate out what pace per mile you’ll need to average, but remember that each mile of a 100k course is so drastically different that you can’t trust mile by mile splits.
Instead, check your watch every five to ten miles and see what your average pace is. That’ll give you a much better indicator of if you are on track to hit your goal. Also, because you will inevitably slow during the final one-third of the race, you’ll want to be ahead of schedule.
If you are aiming for 12 hours and you hit the two-thirds mark at 8 hours, it’s going to be very hard to finish in 12.
I hope this article has stoked your fire and you’re feeling ready to crush one of our 100k training plans! I definitely recommend printing out some copies of the plan in PDF format and plastering them around your house.
Take a screenshot and save it to your photos so you can refer to it even when out of cell coverage. We appreciate any and all feedback so feel free to give us a shout and let us know how things are going.
Alright my friend, it’s time to get out there and execute. You got this!
Our other training plans:
Couch to 5K Training Plan (Free PDF Printable)
Free 12 Week Beginner 10k Training Plan
Couch to Marathon Training Plans (1 Year, 6 Months, 12 Weeks)
Couch to 50k Training Plan (8, 12 and 20 Weeks Out)
How To Prepare for a 50-Mile Run (Free Training Plan)
100 Mile Run Training Plan (FREE Printable)
Chase Parnell is a USATF Level 1 certified running coach and spent many years as an online and high school cross country and track coach. You can find his writing in Trail Runner and Ultrarunning Magazine. He lives in Bend, Oregon with his wife Nikki and three young kids. As a lifelong runner with over 50 marathons and ultramarathons under his belt, he has learned the art and science of running by experience, sometimes the hard way. He is most proud of completing Ultra Trail du Mont Blanc (UTMB), a 100 mile trail race in the Alps, or his 2:35 marathon personal best that he is intent on lowering to sub-2:30 before Father Time crushes his dreams.