The Long Run Is Not a Race: How Long, How Slow, and How to Get It Right

Watch any Saturday morning group run and you'll see it happen. The first few miles are relaxed, everyone's chatting, the pace feels comfortable. Then somewhere around mile four someone picks it up slightly. Then someone else matches them. By mile ten the group is running at a pace that nobody would call easy, everyone's working harder than they planned, and the long run that was supposed to be an aerobic base builder has turned into a race.

Nobody meant for it to happen. It always happens anyway.

I run my long runs alone, so I don't have to fight the group. But I still have to fight myself. In my last marathon block, my goal race pace was 8:35 per mile, and I ran my long runs around 9:30. My longest was 22 miles, and I ran every one of those miles at that easy long run pace. Some days, 9:30 felt almost too slow. Then I ran a 3:33 marathon, a 19-minute PR, and I've never been more convinced that slow long runs work. You can read the full story in how I ran a 19-minute marathon PR at 44.

Here's everything you need to know about the long run: what it's for, how long it should be, how slow to run it, and how to get the most out of it.

What the Long Run Is Actually For

The long run is not about pace. It's about time on your feet.

The biggest benefits are aerobic. Long, easy running builds more mitochondria in your muscle cells, improves your ability to burn fat for fuel, strengthens your heart so it pumps more blood with each beat, and grows more capillaries to deliver oxygen to your muscles. These adaptations happen at easy, aerobic efforts. They don't require you to work hard. They require you to work long.

But the long run does more than build your aerobic engine:

It toughens up your legs. Your muscles, tendons, and bones adapt to the pounding of running for hours at a time. That durability is what keeps your form together late in a race.

It's practice for race day. The long run is where you test your fueling, your gear, your shoes, and even your pre-run breakfast, so nothing surprises you in the race.

It builds mental toughness. Spending two or three hours on your feet teaches you to stay patient and keep going when you're tired. That's exactly what the last 10K of a marathon asks of you.

Running your long run faster doesn't speed up these adaptations in any meaningful way. What it does is turn an easy aerobic run into a hard workout. And a hard workout needs recovery, which means the long run you thought was easy is now eating into your ability to show up fresh for your next workout.

How Long Should Your Long Run Be?

It depends on the race you're training for, how much you're running each week, and how experienced you are. Here's a general guide for the longest long runs in a training block:

A couple of guardrails help keep your long run in proportion to the rest of your training.

Keep your long run in proportion to your weekly mileage. A long run that makes up a very large share of your weekly distance creates a big training load in a single session. The right balance depends on your experience, weekly volume, and how well you recover. Many coaches use roughly 25 to 30% of weekly mileage as a planning guideline. Treat that as a rough guide alongside your overall training load, not a hard cutoff.

Watch the clock, not just the distance. Some coaches recommend capping long runs around 2.5 to 3 hours to limit fatigue and recovery costs. Others favor longer runs for certain marathoners who need more time on their feet. Your experience, training volume, and ability to recover should help determine your limit. That's part of why a slower marathoner might top out at 18 or 20 miles, while a faster runner can cover 22 in about the same amount of time.

For the marathon, most runners do their longest run around 20 miles, about three weeks before race day. My longest was 22 miles, and it gave me a lot of confidence heading into the race. But you don't need to run 26.2 miles in training. Race day adrenaline, a taper, and good fueling will carry you through the last few miles. Our guide to the tapering trap explains why.

How Slow Should Your Long Run Be?

Embarrassingly slow. That's the honest answer.

For many marathon runners, an easy long run might fall roughly 1 to 2 minutes per mile slower than goal marathon pace. Treat that as a starting point, not a rule. Your current fitness, the weather, the terrain, and how tired you are from the rest of your training all affect the right pace. Here's what that range looks like for some common marathon goals:

That feels painfully slow when you know you can run much faster on race day. That's the point. The PR Nerd training plans put long run pace toward the easy end of that range on purpose, because an easy long run is one you can recover from quickly.

The better test is effort. You should be able to speak in full sentences without struggling for breath. If you have to force the pace to hit a number on your watch, slow down, especially on hot or hilly days. The goal is to build endurance without turning every long run into another hard workout. If you train with heart rate, most of your long run should be in an easy, zone 2 effort. Our guide to zone 2 running explains how to find it.

A long run, especially a 20- or 22-miler, will leave you tired. That's normal. But if you're consistently finishing long runs completely exhausted, struggling to recover, or carrying fatigue into your next workouts, you may be running too fast, too far, or both. Want your own numbers? Our pace calculator gives you your long run pace from any recent race.

The Cost of Running It Too Fast

Here's what happens when you run your long runs too fast over a training block. Week one feels fine. Week three, you're a little more tired than usual. Week six, your interval workout falls apart and you can't figure out why. Week ten, you're wondering if you overtrained.

You might not be overtrained in the clinical sense. But if you've been running your easy days too hard, week after week, the accumulated fatigue could be why your workouts are falling apart.

The long run is the biggest single run of your week. It sets the recovery load for everything that follows. Run it at the right pace and you can train hard again within a couple of days. Run it 90 seconds per mile too fast and you're still carrying that fatigue when your next workout comes around. Over a 16- or 20-week training block, that adds up to a lot of compromised workouts. Not every run should feel the same, and the long run is where most runners forget that. Our guide to why every run should not feel the same goes deeper.

This is where group runs make things harder. Nobody wants to be the person who slows everyone down, and when someone surges, the group follows. The fix is simple but takes discipline: run your own pace. If the group goes, let them go. Your training plan is not their training plan, and your recovery needs aren't theirs. Running with faster people on your easy days feels like it's making you better. Usually, you're just piling up fatigue. It's one of the reasons I do my long runs alone.

The Different Types of Long Runs

Not every long run has to be the same. Once you've built a solid base, a few variations can make your long runs more race-specific. Just don't overdo them. Most of your long runs should still be easy.

The easy long run. This is your bread and butter: the whole run at easy long run pace. Most of your long runs, especially early in a training block, should look like this. My 22-miler was all easy.

The progression long run. You start easy and gradually pick up the pace, finishing the last few miles closer to marathon pace. It teaches you to run faster on tired legs without the stress of a full workout.

The marathon pace long run. You run most of the long run easy, then finish with a block of miles at goal marathon pace. A few of my long runs had 3 to 4 miles at marathon pace. It's the most race-specific long run you can do, because it teaches your body to hold race pace when you're already fatigued. The key word is finish. In an 18-mile long run, the first 14 or 15 should be easy, with the last 3 or 4 at marathon pace. Earn the fast miles by running the easy miles easy.

The fast finish. Similar to a marathon pace long run, but shorter and a little faster. You run the final mile or two at a strong effort, closer to half marathon pace.

Here's a simple way to fit them into a training block. In the base phase, keep every long run easy. In the build and peak phases, swap in a progression or marathon pace long run every couple of weeks, and keep the others easy. In the taper, keep them shorter and easy. If you want to understand how those faster efforts fit with the rest of your workouts, read our guide to tempo runs vs threshold runs.

Don't Build It Too Fast, Either

Running your long run too fast isn't the only way to get it wrong. Increasing the distance too quickly can also raise your injury risk. A 2025 study of more than 5,200 runners found that running more than 10% farther than your longest run in the previous 30 days was associated with a higher rate of running-related injuries.

That doesn't mean a 10% increase is automatically safe, or that adding a mile every week is the right approach for everyone. Your recent training, recovery, and running experience all matter. The takeaway is simple: build your long run gradually, and don't make a big jump in distance just because your training plan says it's time.

For what it's worth, here's how I built up to 22 miles. I started my marathon block with a long run of around 12 miles and added about a mile a week, with cutback weeks along the way. I broke down the research in how fast you should really increase your mileage.

Fueling Your Long Run

Once your long runs pass about 90 minutes, fueling starts to matter. More importantly, your long runs are where you practice your race-day fueling plan.

Don't wait until race day to try a new gel or drink. Use your long runs to test exactly what you plan to do in the race: the same gels, the same timing, and the same electrolytes. That's what I did. My long run fueling matched my race-day plan, so by the time I got to the start line, I knew exactly what my stomach could handle. On race day, I never hit the wall.

Our guide to how to fuel long runs and races covers how many carbs you need and when to take them, and our guide to electrolytes for long runs covers sodium and why it matters, especially on hot days.

Recovering After Your Long Run

What you do after your long run matters almost as much as the run itself.

Rehydrate and get some carbohydrates and protein after your run. Carbs help refill your energy stores, and protein helps your muscles start repairing. After long, hot runs where you've sweat a lot, electrolytes help too. Personally, I have protein and electrolytes as soon as I can after my long runs, then a real meal within an hour or two.

Take a nap if you can. Sometimes I'll take an hour-long nap after a big long run, and honestly, it helps a lot. Sleep is when your body does most of its repair work.

Keep the next day easy. The day after a long run should be an easy run, a rest day, or cross-training. Don't stack a hard workout on top of a long run.

Here's the thing, though. If you run your long run slowly enough, you shouldn't feel terrible afterward. You'll be tired, but you shouldn't be wrecked. If you're hobbling around the rest of the day, that's usually a sign you ran it too fast, not that you need a better recovery routine. For a few tools that actually help, check out our guide to recovery tools that work.

How to Know You're Running Your Long Run at the Right Pace

Your long run pace exists for a reason. It should be based on your actual fitness, not your ego or your GPS watch's encouraging notifications.

You're probably running it at the right pace if you can talk in full sentences the whole way, you finish tired but not wrecked, and you show up to your next workout with fresh legs. If you have to force the pace or you're dragging for days afterward, slow down.

That's how the long run works. Slow down and let it do its job.

FAQ

How slow should my long run be? For many runners, an easy long run is roughly 1 to 2 minutes per mile slower than goal marathon pace, but treat that as a starting point. The better test is effort: you should be able to talk in full sentences the whole way.

How long should my long run be? It depends on your race and experience. Typical longest long runs are 6 to 10 miles for a 5K or 10K, 10 to 14 miles for a half marathon, and 16 to 22 miles for a marathon. Keep your long run in proportion to your weekly mileage. Some coaches cap long runs around 2.5 to 3 hours, while others use longer runs for some marathoners.

What's the longest run I should do before a marathon? Most runners peak at around 20 miles, about three weeks before race day. Some experienced runners go to 22. You don't need to run the full 26.2 miles in training.

Should I run my long run at marathon pace? Not the whole thing. Most long runs should be easy. During the build and peak phases, finishing some long runs with a few miles at marathon pace is a great race-specific workout.

How often should I do a long run? Most runners do one long run a week, usually on the weekend. Cutback weeks with a shorter long run every few weeks help your body recover and adapt.

What should I eat during a long run? For runs longer than about 90 minutes, take in carbs, usually from gels or sports drinks, and electrolytes. Use your long runs to practice the exact fueling plan you'll use on race day.

How do I recover after a long run? Rehydrate, get some carbohydrates and protein, add electrolytes after long or hot runs, rest or nap if you can, and keep the next day easy. If you're completely wrecked after every long run, you may be running them too fast, too far, or both.

---

Your PR Nerd training plan includes your exact long run pace based on your current fitness. Build your free plan.