How Many 20 Milers Before a Marathon? Real Numbers for Real Runners

Here’s the big question that pops up every marathon season: do you really need to crank out a bunch of 20-mile training runs? And if so, how many is enough—are you behind if you only manage one or two, or are four or five better?

This isn’t just a number runners obsess about for fun. Your body and brain both need those gutsy long runs, but doing too many might leave you crawling into race day burned out. Getting the right balance can mean more finish line smiles, and less limping.

If you’re training for your first or fifth marathon, knowing how to handle these key marathon workouts makes all the difference out there on the road. Let’s get real about what works, talk through a few myths, and set you up to survive—and maybe even enjoy—those monstrous 20 mile runs.

• Why 20-Mile Runs Are a Big Deal
• How Many 20 Milers Do Most Runners Do?
• Timing and Recovery Between 20 Milers
• Science and Stories: What Works in Real Life
• Smart Tips: Getting Through Your 20s Without Getting Wrecked

Why 20-Mile Runs Are a Big Deal

There’s a reason almost every marathon training plan throws in a few 20-milers. These long runs aren’t just a mental hurdle—they prep your body for what it feels like to be out on the road for hours, and help make race day a whole lot less shocking. Gearing up with a couple of strong 20-mile runs gives you confidence. You know you can handle a huge chunk of the marathon before you even pin on that race bib.

Your body adapts in big ways during these long runs. You teach your muscles to burn fat better (instead of crashing from running out of carbs), and your joints, ligaments, and tendons get used to the pounding. The risk of hitting “the wall” in a marathon drops when you practice staying on your feet that long in training.

Another practical reason: most runners race slower than their easy training pace for the last six miles. Practicing 20-mile runs helps you figure out your sweet spot, not just survive but finish strong. And if anything’s going to expose bad gear or torture snacks, it’s the 20-miler. Better to find those problems now than halfway through your marathon.

In short, 20 mile runs are the best dress rehearsal you get. They aren’t mandatory for everyone, but they sure stack the odds in your favor when you line up for those 26.2 miles.

How Many 20 Milers Do Most Runners Do?

The sweet spot for most marathoners is two to three 20 mile runs during the peak of their marathon training cycle. That’s what you’ll find in the majority of major training plans—think Hal Higdon, Hansons, or even the classic Runner’s World schedules. These big runs usually happen in the last six or eight weeks before your race, spread out with at least a week or two in between each one so you don’t burn out.

If you check out what average runners are actually doing, you’ll see a pattern: experienced folks sometimes sneak in up to four 20 mile runs, especially if they’re gunning for a personal best. First-timers, on the other hand, may stick to just one or two, and that’s perfectly fine too. Plenty of runners cross that finish line with just a single 20 miler under their belt.

Let’s break down what’s common:

• Most beginners: 1–2 long runs of 20 miles
• Intermediate marathoners: 2–3 long runs of 20 miles
• Advanced/competitive runners: 3–4 (sometimes up to 5) if their bodies handle higher mileage

One interesting stat: according to data from Strava’s annual marathon analysis, over 60% of recreational marathoners log two or fewer 20-milers before race day. That’s a real-world check against the idea you “must” do three or more. Volume matters, but so does not getting hurt.

Here’s the thing: it’s not all about hammering as many long runs as you can. Your body needs time to build fitness and bounce back. Quality matters more than just going through the motions. If you need to swap a 20-miler for a slightly shorter long run so you stay healthy, go for it. The magic really happens in consistent training, not just a few epic sessions.

Timing and Recovery Between 20 Milers

You can’t just stack 20-mile runs back to back and hope for the best. Your body needs time to get stronger, and your brain needs to chill out, too. Most marathon training plans (think Hal Higdon, Hanson, or even some pro runners) spread out those big 20 mile runs. Usually, you’ll see one every 2-3 weeks during your main build-up.

Spacing gives your muscles and joints a break. The magic happens in recovery, not just the run. Trust me, nobody wins medals for having knees that feel shredded. Cramming these runs too close can lead to more soreness, overuse injuries, and a total lack of motivation by the time race day hits.

• Most runners go for three weeks between their hardest long runs, especially the 20 milers.
• If you’re building up to your first marathon prep, even every 3 or 4 weeks is fine.
• Advanced runners might do a 20 miler every other week in peak training, but only if they recover fast and have a big base.

Recovery starts as soon as your feet stop moving. Here’s what actually helps:

1. Eat something with carbs and protein within 30 minutes. A turkey sandwich or chocolate milk works—don’t overthink it.
2. Hydrate right after and throughout the day. Water is great; toss in some electrolytes if you sweat buckets.
3. Take it easy the next day. Go for a mellow walk, use a foam roller, or spin on a bike—but don’t try to “make up” missed miles.
4. Prioritize quality sleep. That’s when your muscles actually rebuild.

Here’s a quick look at how marathoners usually space out those tough long runs:

It's totally normal if you feel wiped out for a couple days after a long run like this. Don’t rush the next hard session. The goal is to show up healthy and confident to the start line, not to see how many times you can smash your legs before race day.

Science and Stories: What Works in Real Life

The science behind those 20 mile runs is pretty solid, but there’s a lot of real-world tinkering going on, too. Here’s what we know for sure: our muscles and brains get tired after hours of pounding the pavement. That’s why the long run is a marathon training non-negotiable. Studies from sports science labs (like one published by the Journal of Applied Physiology in 2018) show that regular long runs teach your body to use fat for fuel and keep your legs from turning into lead during the final miles. The sweet spot for these perks is usually anything over 16 miles, but the magic starts shining around the 20-mile mark.

If you look at what pro marathoners do, most don’t go wild with weekly 20 milers. Even elite runners keep it to about two to four of these big ones in their build-up. According to coach Greg McMillan, too many monster long runs can leave you flat on race day. He’s coached everyone from first-timers to Boston qualifiers, and he’s quick to remind runners: you’re trying to show up fresh, not fried.

Amateur runners have stories all over the map. Some folks hit three full 20-milers and crush it. Others skip the classic 20 and top out at 18 but still finish strong. It really comes down to what your legs (and schedule) can handle. But most marathon plans for regular folks aim for two to three of these long runs before race day.

Here’s a nugget from the trenches: Some runners find the first 20-miler feels like a mini-marathon. The second? Much less scary. By the third, you’re just testing fueling and pacing. This isn’t science, but most runners agree—having one or two go well gives you way more mental grit than hitting just one and hoping it works out.

So don’t stress about a magic number. Stick to a solid plan, fit in at least two to three 20 mile runs if you can, and listen to your body. The stories prove it: what really works is persistence and smart training, not just chasing numbers for the sake of it.

Smart Tips: Getting Through Your 20s Without Getting Wrecked

Let’s be honest, marathon training can beat you up if you’re not careful. You want those big 20-mile runs to make you strong, not drag you to the start line already broken. Here’s how to keep your training on track while staying sane and healthy.

• Run Slow, Finish Strong: Long runs aren’t about speed. Keep your pace one to two minutes slower than your expected marathon pace. This teaches your body to burn fat and build endurance. You don’t “win” a 20 mile run in training, you survive it so you can crush race day.
• Start Early With Fuel: Don’t wait until you’re dragging to eat. Grab a gel or some chews every 30-45 minutes. Most runners need 30-60 grams of carbs per hour. Sip water or a sports drink throughout. If you’re not practicing your race fueling now, you’re risking the wall later.
• Mix In Walk Breaks: Even seasoned runners swear by walk breaks, especially in the last few miles. It’s not “cheating”—it lets your legs recover so you stay consistent and reduce injury risk.
• Get Real With Recovery: After a long run, toss on some dry clothes, down a carb-and-protein snack, and chill with your feet up. No heavy chores or long walks at the mall. Sleep is everything this training cycle—seven hours is the bare minimum, and if you can nap, do it.
• Track Your Trends: If you’re always struggling at the same distance, bump up your midweek long run or your total weekly mileage. Better to troubleshoot before race day than after.

Listen to your body. If something hurts more than the usual tired legs, don’t push through—swapping a 20-miler for a shorter run or cross-training session is always better than heading into the race nursing a real injury.

And remember, no single long run is make-or-break. It’s the combined effect, along with recovery and smart pacing, that really preps you for marathon day. If you focus on building fitness, not just checking off miles, you’ll toe the line feeling strong, not wrecked.