The Marathon Long Run: Essential Guide + Variations To Try

The marathon long run is arguably the primary differentiating factor between a marathon training program and training for a shorter race, such as a 5k, 10k, or even half marathon.

Because the full marathon distance is a whopping 26.2 miles or 42.16 km, runners must build up their aerobic endurance to handle the marathon on race day.

In this marathon long run guide, we will help you nail the long run so that you feel confident that you can cross the finish line on race day.

We will cover: 

Let’s get started!

What Should Your Long Run Pace Be?

There are a couple of options for performing marathon long runs.

For beginners training for their first marathon race, I almost always stick with an easy pace for long runs.

Running at an easy pace for the long run will help you focus on holding up your endurance rather than adding additional stress to the body with marathon pace work or speed work.

Doing a long run is inherently taxing on your body because you’re on your feet for a long time, using your muscles continuously for a couple of hours.

You are also stressing your bones and joints, elevating your heart rate and respiration rates without reprieve, increasing your body temperature, and depleting your glycogen stores.

The faster your long run pace relative to your goal race pace, the higher the intensity and the greater the stress on your body.

Since most of the best marathon training plans have a weekly long-distance run, you can imagine how marathon pace long runs could quickly lead to overtraining, burnout, or injury.

This is especially true in the context of the overall high weekly mileage for marathon prep, which also likely includes other speed work like interval workouts and tempo runs.

The primary objectives of the marathon long run and longer training runs are to build up endurance, strengthen the cardiovascular system, increase blood volume, help your body adapt to higher weekly mileage and a longer time of your feet, and develop your aerobic base.

The good news is that you will get many of the aerobic and cardiovascular adaptations of long training runs when you run at an easy pace; it is not necessary to run at your goal marathon race pace.

In fact, as mentioned, habitually doing so can increase the risk of injury and overtraining, and it significantly increases your recovery time.

Rather, running your long runs at a slow pace effectively accomplishes the intended goals of the long distance running while also protecting your body from overtraining and burnout by reducing the stress imposed on the body.

A slow long run pace will mean that you won’t have to take numerous rest days after your longer runs in order to recover enough.

Polarizing your training with easy easy runs and fast speed work also prevents the risk of injuries because your biomechanics change at different running speeds.¹Filipas, L., Bonato, M., Gallo, G., & Codella, R. (2021). Effects of 16 weeks of pyramidal and polarized training intensity distributions in well‐trained endurance runners. Scandinavian Journal of Medicine & Science in Sports, 32(3). https://doi.org/10.1111/sms.14101

‌This variety reduces the risk of overuse injuries compared to running at the same pace all the time because stress and strain on any one tissue are not as repetitive.

In general, most running coaches recommend a long run pace that is at least 1–3 minutes per mile slower than your 10k pace for shorter races (10k and half marathon) or at least 1-2 minutes per mile slower than your marathon race pace for marathon training long runs.

For example, if you want to run a marathon at 9:30 min/mile pace, you would want to do your long training runs at 10:30-11:30 pace. 

For marathon runners who are more comfortable with kilometers, your long run pace should be about 50-90 seconds slower per kilometer slower than your marathon pace. 

If you are using heart rate training, marathon long runs should be performed in zone 2, or around 60-70% of your maximum heart rate.

What Are The Benefits Of Long Runs On A Marathon Training Plan?

Although longer runs are certainly tiring and can be intimidating, there are many benefits of long runs for marathon training or other long distance running events.

Some of the expected physiological adaptations to long-distance running with the long run workouts include:

• Improvements in the efficiency of your cardiovascular system (stronger heart muscle, greater stroke volume, greater blood plasma volume). These adaptations to the heart mean that every time your heart beats, it can pump more blood through the aorta into circulation. Because a greater volume of blood is circulated per beat, you will have a lower heart rate at the same sub-maximal pace while still meeting the oxygen demands of the muscles.²Hellsten, Y., & Nyberg, M. (2015). Cardiovascular Adaptations to Exercise Training. Comprehensive Physiology, 6(1), 1–32. https://doi.org/10.1002/cphy.c140080
• An increase in lung tidal volume. Like increases in stroke volume, you get more air and oxygen into your lungs per breath because you breathe more deeply. Therefore, your respiration rate can slow down and breathing becomes more controlled. 
• An increase in capillary density in your muscles and circulatory system for better oxygen delivery.
• An increase in mitochondrial density in Type I (slow-twitch) muscle fibers and flexible Type IIa (intermediate) muscle fibers also improves their ability to produce energy through aerobic metabolism.³Plotkin, D. L., Roberts, M. D., Haun, C. T., & Schoenfeld, B. J. (2021). Muscle Fiber Type Transitions with Exercise Training: Shifting Perspectives. Sports, 9(9), 127. https://doi.org/10.3390/sports9090127

• ‌Metabolically, your muscle fibers also become more efficient at burning fat fast to rely more heavily on fat for fuel at higher intensities rather than relying predominantly—or nearly exclusively—on carbohydrates. This means that your body can conserve glycogen stores on race day by burning fat and doing more “work“ with the ATP generated by burning glycogen. As a result, glycogen storage in the muscle and liver can last longer—referred to as glycogen sparing—helping prevent the dreaded “bonking” or “hitting the wall” that occurs when glycogen is depleted.⁴Hughes, D. C., Ellefsen, S., & Baar, K. (2017). Adaptations to Endurance and Strength Training. Cold Spring Harbor Perspectives in Medicine, 8(6), a029769. https://doi.org/10.1101/cshperspect.a029769
• Mental and physical stamina to run on tired legs.
• Strengthening the muscles, joints, bones, and connective tissues in your legs to handle “time on your feet“ for long-distance running.
• Gastrointestinal adaptations to digesting and absorbing carbohydrates while you are running.

In addition to physiological adaptations, long-distance runs in marathon training also give you an opportunity to practice the logistics for race day. 

You must rehearse your hydration and fueling plan, including what, how much, and when you plan to take in carbs (energy gels, sports drinks, etc.), electrolytes, and drink fluids on race day.

Along these lines, your marathon long runs are a good opportunity to nail down other practical details like what pacing strategy you will use, what running shoes feel best, what clothing prevents chafing, etc.

The longest long run in your training cycle is essentially your dress rehearsal for race day, so you can use this to make sure you have ironed out the kinks in your carbs and your hydration plan.

When Should I Do My Last Long Run Before A Marathon?

You do not want to get to race day on tired legs, so it is important to taper down the distance of your longer runs in the final weeks of your marathon training plan.

The longest long run in your marathon build up should be at least 3 weeks before race day. Then, you should start to taper down the distance of the long training runs so that you have enough recovery time before the big day.

For example, if your longest long run in your marathon training program is a 20-miler, your training cycle will gradually build up the longer runs to the 20-miler, which will finally occur about 3-4 weeks out from race day.

Then, to ensure there is enough recovery time and time for the marathon long run adaptations to occur to actually benefit you during the race, you will run increasingly shorter long runs the closer you get to marathon day over the taper period.

If you run a 20-mile run as your longest long run 4 weeks from race day, you might do an 18 mile long run 3 weeks out, a 14 miler 2 weeks from race day, and no more than 10 miles as your longest run a week from the marathon.

If it is your first marathon, you might drop the distances of these longer runs even more—to 10-12 miles two weeks out and an 8 miler as your last long run.

An Olympic distance runner and elite distance runners who have plenty of experience with the marathon race distance will likely incorporate some speed work or at least goal marathon pace miles into these long runs.

However, beginners training for their first marathon should take all of the marathon training long runs—especially the final several in the training program—at an easy pace.

What Are The Best Marathon Long Run Variations?

In addition to long runs done at an easy pace, advanced runners can do long run variations in their training program.

A progressive long run workout is one in which you start at an easy run pace (like your normal comfortable long run pace), and then you gradually and progressively run faster, often hitting your goal marathon pace or even faster for the last several miles of a longer distance run.

Here is an example 18 mile long run progression workout with different race pace efforts built in:

Marathon Progression Long Run: 18 Miler

• Warm up at an easy run pace (90-120 seconds slower than your goal marathon pace, or around your normal warm up pace or long run pace)
• 3-6 miles: 90 seconds per mile slower than your goal marathon race pace 
• 6-9 miles: 60 seconds per mile slower than your goal marathon pace 
• 9-12 miles: 30 seconds slower per mile than your goal marathon race pace 
• 12-18 miles: goal marathon pace, finishing with a kick

You can also incorporate marathon pace training in the marathon long run in an interval training style rather than one long chunk as you might with tempo runs or in the progression long run variation just described.

Here is an example 20 mile long run workout with speed work built in. Note that this type of advanced long run variation is not intended for beginners:

20 Mile Marathon Long Run With Speed Work

• Warm up at an easy run pace (90-120 seconds slower than your goal marathon pace, or around your normal warm up pace or your usual long run pace). Until mile 4, use a normal long run training pace.
• For the next 15 miles, you will do a fartlek workout: 60 seconds at marathon pace, 60 seconds at a normal long run pace, 60 seconds at half marathon pace, 60 seconds at a normal long run pace, 60 seconds at your pace for tempo runs (slightly slower than 10k pace), 60 seconds at a normal long run pace, 60 seconds at 5k pace, 60 seconds at a normal long run pace. Keep repeating these intervals as your fitness level allows.
• Cool down the final mile with an easy pace, as you might after speed workouts or normal training runs.

What If The Long Runs On My Marathon Training Plan Don’t Go Well?

While there is no denying the importance of the long run in a marathon training plan, in my years of coaching first-time marathon runners and advanced runners alike, I have found that many runners in general, often put too much stock in the marathon long run.

This is not to say that you can do away with longer runs in your marathon training plan and expect to have an easy time hitting goal marathon pace for 26.2 miles on race day.

However, I do want to draw attention to the fact that if you are feeling very anxious about marathon long run distances, marathon long run paces, and getting in every single marathon long run on your training program, you might be missing the forest for the trees so to speak.

The marathon long run is one of the cornerstone workouts in the best marathon training plans, but it is not the only important workout.

All of the other runs are also important pieces to the puzzle, for example:

• Easy runs will also help build up your cardiovascular and musculoskeletal endurance.
• Speed workouts will help you become more comfortable with running faster.
• Tempo runs and longer runs that incorporate some marathon goal pace work will help you improve your lactate threshold and comfortability with marathon race pace and even improve your metabolic efficiency for conserving glycogen for longer runs.

The reason that I mention all of this is that for almost every marathon build up, you will have one or two long runs that don’t necessarily go exactly how you want them to.

Perhaps you might underfuel or try a different type of energy gel during the long training run and find that you get stomach cramps or run out of glycogen and “bonk“ due to the lack of carbohydrates.

Particularly if you are training for your first marathon, the long run is the best time to experiment with trying different gels, figuring out your hydration strategy, seeing what types of carbohydrate sources settle best when you are trying to hold marathon pace, and even which pair of running shoes and clothing you are going to wear on race day.

As you use these training runs to work out the“kinks“ for your marathon race day plan, you are likely to have a few “misses”—finding that something doesn’t work well for you.

While this can be frustrating when you are trying to do the marathon long run, it is much better to discover that a certain energy gel gives you cramps or your glycogen stores deplete and that you need to take in more carbohydrates than is generally recommended for many marathon runners, in training runs rather than during your first marathon race.

I always tell the runners I coach that the training runs are dress rehearsals and it is OK to iron out the kinks.

The more troubleshooting and information we can gather before race day, the more likely you will have a smooth experience when you stand at the starting line.

In most cases, when marathon workouts or training runs don’t go according to plan, I don’t have the runners that I coach try again to do the same workout later that week.

In fact, especially if the runner is feeling sick or that they are potentially staving off an injury, I would probably have them forgo the long run and easy training runs and swap them for rest days or cross training days until we are confident that they are in the clear.

Unless you develop stomach cramps or seem to have problems with glycogen storage and bonking very early into the long run and then immediately switch to an easy run, I generally do not recommend trying your marathon long run again that same week.

Once you get into the longer distances in your marathon training runs, you will often be training on tired legs.

Doubling down with trying to do a second marathon long run attempt in the same week can just add more mental stress and accumulated fatigue on tired legs.

The only caveat here would be if you are feeling good and you are early in the marathon training program build up.

Then, we might swap the long run for easy runs if the long run didn’t go to plan.

Overall, marathon training long runs are tough, but they will get you ready to cross the finish line.

To start working on your hydration strategy to practice in your long runs, check out this next guide:

References

• 1
  Filipas, L., Bonato, M., Gallo, G., & Codella, R. (2021). Effects of 16 weeks of pyramidal and polarized training intensity distributions in well‐trained endurance runners. Scandinavian Journal of Medicine & Science in Sports, 32(3). https://doi.org/10.1111/sms.14101
• 2
  Hellsten, Y., & Nyberg, M. (2015). Cardiovascular Adaptations to Exercise Training. Comprehensive Physiology, 6(1), 1–32. https://doi.org/10.1002/cphy.c140080
• 3
  Plotkin, D. L., Roberts, M. D., Haun, C. T., & Schoenfeld, B. J. (2021). Muscle Fiber Type Transitions with Exercise Training: Shifting Perspectives. Sports, 9(9), 127. https://doi.org/10.3390/sports9090127
• 4
  Hughes, D. C., Ellefsen, S., & Baar, K. (2017). Adaptations to Endurance and Strength Training. Cold Spring Harbor Perspectives in Medicine, 8(6), a029769. https://doi.org/10.1101/cshperspect.a029769