There's something about 100 miles.
In ultrarunning, it's a distance that’s acquired a special significance.
And it's the distance behind the biggest names in the sport: Western States, UTMB, races that have grown to define modern ultrarunning.
Run a few ultras and, sooner or later, someone will ask whether you're going to run a hundred.
It's tempting to think of it as a 100K with another 60K bolted onto the end. It isn't - a hundred is different. Those extra kilometres arrive after you've been ‘running’ for a very long time.
Small problems have had time to become big ones. Your legs have taken a battering. You've been eating for hours. You may have been through a night. And you've still got something close to a marathon and a half to go.
My stomach knows it. I rarely have GI problems when I run. I've run much further than 100 miles without them. And yet, I've had stomach problems in every 100 miler I've done. Lakeland 100 this year was just the latest chapter.
The foundations are the same as for a 50K or 100K. But the longer the race gets, the more durability, fuelling, darkness, kit and problem-solving start to matter.
This blog is about how I think about preparing an athlete for their first hundred, starting with the foundations and gradually getting more race-specific.
Phase one: build the foundation
First, you need to put the basics in place…
Build the aerobic base
The most important part of training for your first hundred is also the least exciting: months of consistent running.
Most of that running should be easy with a sprinkling of hills, tempo, strides and other faster work. You're building the aerobic engine that everything more specific will eventually sit on.
And remember, a solid week you can repeat beats a big week that costs you ten days of recovery.
You can read more about the aerobic base at www.rununbound.com/blog/ultra-brew
Build durability
Aerobic fitness will get you a long way. But you also need durability: the ability to keep moving as fatigue accumulates.
Progressively longer outings build that durability, exposing you to muscular fatigue, sore feet and the general wear that a two-hour run simply doesn't.
But longer isn't automatically better. You don't need to run 50, 60 or 70 miles in training to prove you can. At some point the injury risk and recovery cost of a very long run starts to outweigh what you gain from it.
Strength supports durability. It's part of what keeps your stride intact as you tire. It matters even more in the mountains, where thousands of repeated eccentric contractions on the descents can quickly expose legs that haven’t been prepared for them.
Strength work should start early rather than being bolted on once the running gets big. As running volume and specificity increase, the strength load can reduce towards maintenance.
For mountain races, the training should also progressively include the eccentric loading and descending that the race will demand, either in the gym or in the hills.
Here’s more on why and what you can do: www.rununbound.com/blog/strength-matters
Use long runs and back-to-backs for different jobs
A long day and a back-to-back weekend are great training stimuli, but they train different things.
A long day exposes you to the problems that only start appearing after several hours. Fuelling fatigue. Sore feet. Kit that was perfectly comfortable for the first four hours. The mental drag of simply being out there for a long time.
It also gives you repeated practice at eating, drinking and managing yourself while continuing to move.
A back-to-back gives you something different. You finish Saturday tired, recover as best you can, then get up on Sunday and start moving again on legs that aren't fresh. It's a useful way to accumulate a lot of race-relevant work without making one training session enormous.
The aim isn't to recreate the race in training. It's to take manageable pieces of what the race demands and progressively prepare yourself for them.
Progression matters. Your first long run isn't eight hours. Your first back-to-back isn't six hours on Saturday followed by three on Sunday. You build the load as your ability to absorb it builds.
None of this is unique to the hundred. It's the entry fee. What separates a hundred from everything shorter starts in phase two.
You can see an example of how I use back-to-backs at www.rununbound.com/blog/train-mountain-ultra-london
Phase two: build the race
The foundation you develop from Phase one gets you to the start line capable of running a very long way.
It doesn’t prepare you to run this race, on this course, in whatever conditions turn up on race day, so let’s try to remove as many unknowns as possible beforehand.
Train for your course, not for “100 miles”
There’s no single physical demand called 100 miles.
A flat, runnable hundred and a mountainous one with thousands of metres of vert are the same distance and almost different sports. The Thames Path 100 and the Grand Raid des Pyrénées have little in common beyond the distance on the entry form.
Review the course. Look at how much climbing and descending there is, how technical the ground is, how far apart the aid stations are, whether you'll use poles, what you'll have to carry and the likely conditions. Then make the training progressively look more like that.
A flatter hundred has its own challenges: deciding on your race strategy when the course never hands you a natural excuse to walk.
Train to problem-solve, not just push through
In shorter races, you’re often rewarded for pushing through discomfort. Over a hundred miles, you need to get better at diagnosing problems and solving them if you can.
Something that’s a minor irritation early in the race can end your day at mile 70 if you ignore it.
That's a mindset you train, not try to adopt on race day. Don't treat every loss of energy in a long training run as something to grind through. Stop. Work out what's happening.
Have you eaten and drunk enough? Fix it if you can. Long runs are a rehearsal for exactly this kind of decision-making. Pushing through everything is a habit that helps until it doesn’t.
That said, sometimes you’ll try things and they won’t help. I felt nauseous very early in the Lakeland 100 this year, and I tried all sorts of food combinations, but nothing worked. In the end, I just had to carry on, nausea and all.
Decide on your pacing strategy
Pacing conservatively on effort, well inside your ceiling, is the right call for most first hundreds. If you’re genuinely competing for a podium, place or qualifying time, you may want to push things and accept the greater risk. Either way, decide which race you’re running before you start.
A pace plan can give structure to a hundred, but you need to stay flexible. Terrain, weather and accumulated fatigue can change things. Heart rate can also be unreliable: nerves, caffeine, the poor night’s sleep before the race can all have an impact.
So whatever the spreadsheet says, use effort to govern what you do.
Expect to slow down over the race. That’s not necessarily evidence that you paced it badly. Muscle damage and fatigue accumulate over 100 miles and make even pacing challenging if not impossible.
Practise your fuelling, don't just have a plan
Given my own record with GI problems at this distance, I'm not about to pretend fuelling is easy.
A broad range such as 60 to 90g of carbohydrate an hour can be a useful reference. But the real question is have you tried it and tolerated it over many hours?
And tolerance isn't the only issue. Something you happily eat after two hours can become deeply unappealing after twelve. Variety and avoiding taste fatigue matter too.
The difference between my two Autumn 100s came down almost entirely to this. First time round, I ate whatever the aid stations offered and paid for it, walking for ten minutes after the later checkpoints just to let my stomach settle.
Second time, I brought my own food, adapted from what worked for me over a much longer day on the Bob Graham. My stomach held up.
I still don't fully understand why this distance hits so differently to every other distance I run, but rehearsing the actual race strategy, repeatedly, in training is the best way to reduce the uncertainty.
You can read more at www.rununbound.com/blog/a-tale-of-two-100-milers.
Test your feet and your kit
Shoes, socks, blister management, pack, poles, headtorch and layers all need testing in training.
Your feet can swell over a long day, so test your shoes and socks thoroughly and have options if shoes that felt great at mile 20 feel tight at mile 70.
Small problems left untreated don't stay small, either. I coached an athlete who developed a blister early in a hundred and kept running rather than stopping to deal with it. Ten miles later he’d altered his gait enough that another problem had developed and his race was over. A blister is a five-minute fix.
And nothing new on race day really does mean nothing new. I once switched into a new shoe / sock combo for a race and spent the day regretting it.
Practise the night. Don't train sleep deprivation.
Most hundreds put you through at least part of a night, so practise moving in the dark: running by headtorch, judging terrain and effort with different visual cues, and managing layers as the temperature drops. Expect to be slower in the dark. Learn by how much. And factor it into your race plan.
You don’t need to deliberately deprive yourself of sleep. Finishing the occasional long run after dark gives you useful exposure without turning sleep deprivation into a workout.
Make race day boring
Cut-offs, checkpoint logistics, drop bag rules, mandatory kit, crew and pacers aren't exciting parts of preparing for a hundred. Sort them out before race week.
A hundred is partly an exercise in problem solving while being progressively less capable of doing it. Having a plan at the start means less decision making during the race.
So know what's in your drop bag. Know where your spare batteries are. Know what you'll do at an aid station. If you're using crew, make sure they know what you want from them. If you're using a pacer, have that conversation before you're 70 miles into the race.
I hadn't really planned for a pacer in my first Autumn 100 and ended up recruiting my wife by frantic message with a few hours' notice. It worked but I wouldn't recommend relying on that approach.
You can read more at www.rununbound.com/blog/crewing-tips
Expect bad patches
Feeling awful at mile 60 doesn’t tell you how you’ll feel at mile 70. A hundred is a long way, and a bad patch doesn’t mean things will keep getting worse. There’s an ebb and flow, with good patches and bad ones arriving and passing for reasons that aren’t always obvious.
Sometimes there’s a problem that needs fixing. Sometimes you need food, fluid, another layer or to slow down. Sometimes it just passes.
Chunk things down and go checkpoint to checkpoint. A checkpoint can be a reset. Treat it as the start of a new leg rather than the continuation of a bad one. If you need it, you’ve usually got time for a proper break.
There’s a version of you at mile 80 who will make a completely reasonable case for stopping. Sometimes that version is right: genuine injury, a medical call, conditions that have made continuing unsafe. Often, it isn’t.
It’s worth deciding in advance, while you’re still capable of thinking clearly, what would justify stopping. Not so you push through something you shouldn’t, but so mile 80 isn’t the first time you’ve thought about the difference.
Before you decide: Stop. Refuel. Rehydrate. Phone a friend. Then decide.
Phase three: get out of your own way
By the time you've built the foundation and added the specifics, most of the work’s done.
Recover from the training
This matters throughout the block, not just in the final weeks.
Training for a hundred creates an obvious temptation to think more is better. Longer long run. Bigger back-to-back. One more big week because the race itself is so enormous. But a huge training weekend is only a positive if you recover from it. If it costs you the next fortnight, it's taken more than it gave.
Easy days need to be easy. Bigger blocks need recovery around them. Strength needs to flex with the running load. Niggles need addressing.
You want to do just enough training to arrive ready to race. Not reach the end of the block having completed as much training as you could possibly survive (just). Better to be under than overcooked.
And this is true mentally as well as physically. I rolled January Spine recovery straight into the Lakeland 100 build. Physically, I was fine. Mentally, I was tired. I’d lost some motivation in the final weeks and stood on the start line wanting to get it over with rather than really wanting to race.
Being ready for a hundred isn’t just about whether your legs have recovered from the training. You’re asking yourself to spend a very long time doing something difficult. Starting already tired of the process isn’t a great place to be.
Being ready to race includes wanting to race.
Then taper
Something in the region of two to three weeks tends to be sensible, though there's no fixed number. Training history, accumulated fatigue and the size of your final specific block all play a part.
Reduce volume. Keep the frequency and a little intensity to stop you feeling stale. Reduce the strength load.
And resist the urge to fit in one more long run because you've suddenly started doubting everything you've done. You won't gain much useful fitness in the final fortnight. You can still accumulate plenty of fatigue though.
The work is done. You want to stand on the start line of your first hundred feeling like you'd quite like to go for a run.
So where does this leave us?
None of this is exciting, and it isn’t meant to be.
What makes a hundred different from everything shorter is time: enough of it for a blister to become a limp, for one too many gels to become persistent nausea, for a pace that felt fine at mile 20 to unravel.
Nothing in this piece stops that happening. But if you know where the problems are likely to come, you can train in a way that helps prepare you for them or at least gives you a better chance of managing them when they show up.
The principles are simple.
Build the runner. Months of consistent aerobic training, enough strength and durability work to keep moving as fatigue accumulates, and long runs and back-to-backs that build progressively.
Build the race. Train for the course you’re running. Rehearse your fuelling, feet, kit and night running. Practise problem solving and make as many race-day decisions as you can before you start.
Then get out of your own way. Recover from the training, taper, and arrive at the start line physically fresh and wanting to race.
None of it will make your first hundred easy.
The aim is to give the version of you who reaches mile 70 the best possible chance of dealing with what comes next.