I’ve coached and crewed ultrarunners for a decade. The mistakes are the same. I’ve made all of these myself; most of my training partners have, too. None of them are signs of a bad runner. They’re signs of a runner who hasn’t yet noticed the pattern.
Here are the seven that show up most.
1. Running easy days too hard
The biggest one. Most ultrarunners run their easy days at 75–80% effort instead of 65–70%. The pace feels productive — it’s faster than truly easy — but it’s the gray zone where you’re too hard to recover, too easy to drive adaptation. The result: a runner who’s always slightly tired, never quite gets faster, and breaks down somewhere around week 12 of a training cycle.
Fix: On easy days, run by HR or by talk test. If you can’t hold a conversation in full sentences, slow down. The discipline of running embarrassingly slow on easy days is what makes hard days possible.
2. Skipping the back-to-back long run
Most ultrarunners do one long run on Saturday and call it the long run. The runners who finish ultras well do a long run on Saturday AND a moderately-long run on Sunday — the back-to-back. The Sunday run is typically 60–75% the length of the Saturday run, done easy.
The back-to-back teaches your legs to run on already-fatigued legs. There is no other workout that does this. A 28-mile Saturday is good. A 28-mile Saturday plus an 18-mile Sunday is what wins races at mile 80.
Fix: Add a Sunday medium-long run after every Saturday long run. Ten weeks of this will transform a race.
3. Doing intervals because they feel productive (when you should be running easy)
Intervals are not the problem. Doing intervals at the wrong time is the problem.
Most ultrarunners think: “I should be doing speed work, that’s how to get faster, faster ultrarunners do mile repeats.” So they add a tempo run on Tuesday and a hill repeat workout on Thursday — and now they have three quality days plus a long run, and they’re running themselves into the ground.
For most ultrarunners, the right ratio is 80% easy + 20% quality. If you’re running 6 days a week, that’s about one quality day. Maybe two if you’re advanced. Three is too many for almost everyone.
Fix: If you’re tired, drop the intervals before you drop the easy mileage. The volume is the engine. The intervals are the polish.
4. Under-fueling long runs
Most ultrarunners run 4-hour training runs on a banana and 16 oz of water. Then race day comes and they “don’t know why” they bonked at hour 6.
If you don’t fuel in training, your gut doesn’t learn to absorb calories under load. The race-day bonk isn’t a fitness problem; it’s a digestive-training problem. The runners who can eat 300 calories per hour on race day practiced it on every long run.
Fix: Treat every long run over 90 minutes as a fueling rehearsal. Eat the same things you’ll eat on race day. Drink the same drinks. Your stomach is a trainable system.
5. Recovery weeks that aren’t actually recovery
Most ultrarunners write “recovery week” on the calendar and then run 75% of their normal mileage at normal intensity. That’s a moderate week, not a recovery week. The body doesn’t fully recover until volume and intensity both drop substantially.
A real recovery week is 50–60% of normal volume, mostly easy effort, with one optional shorter quality session. It looks under-trained on paper. It’s exactly what builds adaptation between hard blocks.
Fix: Plan recovery weeks every 4th week. Make them genuinely recoverable. The training cycle is sets and reps, not a continuous push.
6. Comparing your training to social media
You see another runner posting a 30-mile training run with 7,000 ft of vert. You wonder if you should be running that volume. You add miles. Your training breaks down.
Most of what you see on running social media is curated — the best workouts, the longest runs, the highlight reel. Nobody posts the 5-mile recovery run on Tuesday. Nobody posts the week they took off because their hip was tweaked. The aggregate impression of “everyone is running more than I am” is a mathematical artifact of selective posting.
Your training is yours. The runner with the better Instagram is not necessarily having the better training cycle. Many of the most-Instagrammed athletes are over-trained and DNF in races they should have won.
Fix: Stop comparing. Run the volume your body and life support. The right training is the training you can sustain for 16 weeks without breaking down. That’s the only training that matters.
7. Not sleeping
The single most under-discussed training input. Most ultrarunners try to add a hard run instead of adding an hour of sleep. Sleep is when adaptation happens. A runner sleeping 6 hours a night and running 70 mpw will improve less than the same runner sleeping 8 hours and running 55 mpw.
Sleep is the cheapest, most effective training intervention available. It’s also the easiest to skip because nothing posts well.
Fix: Treat 8 hours of sleep as a non-negotiable part of training. If life doesn’t allow 8 hours, drop volume before you drop sleep. Sleep first, miles second.
The honest summary
Most ultrarunners aren’t held back by their genetics, their volume, or their intensity. They’re held back by 1–3 of these mistakes, repeated for years.
The good news: all seven are correctable. The improvement comes from subtraction, not addition — running easy days slower, dropping the third interval session, sleeping more, comparing less. The runners who make these fixes consistently improve through their 30s and 40s long after the runners who don’t have plateaued.
The bad news: the corrections feel boring. The runner doing the right training is doing less obvious work than the runner doing the wrong training. There’s no Instagram for “I ran 8 minute pace today instead of 7:30 pace, just like I should have.”
Run the boring miles. Skip the impressive ones. Race the result.