How Many 20 Mile Runs Before Marathon?

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There’s always been a bit of a debate as to how many 20 mile runs before a marathon you should do.

Some say two times a week is a good baseline, but others believe that once every two weeks is more than enough. There are also those who proclaim that 20-mile runs are completely unnecessary, especially if you follow the Hansons Marathon Method. So what’s the truth?

To put the question, “how many 20 mile runs before marathon you should do?” to rest once and for all, we’ve made this guide on everything you need to know about marathon training plans. We’ve also included a dedicated 5K training plan you can follow in 5 weeks at the end of this post. 

Let’s dive right in! 

How Many 20 Mile Runs Before Marathon?

20-mile runs appear in marathon training plans so often they’re basically a staple, so it’s fair to assume that you have to run the whole 20 miles at least once before a marathon. 

According to some coaches, experienced runners should extend their weekly long runs to nearly as long as given race time to allow their bodies to get used to the distance.

These runs must be executed at a forgiving pace to prevent overuse injuries, ideally 60 to 70% of the original marathon goal pace.

So if you normally complete a full marathon in 3 hours and 30 minutes, training should only cover between 20 to 23 miles in the same duration.

For many, 20-mile runs break an invisible barrier. If the body can run 20 miles at a comfortable pace without pushing it to its limit, it can easily complete a full marathon of 26.2 miles.

In part, this is more mental than physical: you’ve already passed 20 miles, what’s 6.2 miles more?

With that said, most runners find one 20 miler per week to be the “sweet spot” of marathon training; enough to work a sweat and get the distance in, but also enough to allow long-run workouts and post-run recovery.

Three 20-mile runs per week is also an option, but not recommended as it greatly increases the risk of injury.

Remember: 20 miles isn’t an easy feat. It takes an average of 2.5 to 3 hours to complete. Running for that long can take a toll on your body, especially if you’re training more than four days a week.

Is 20 Miles the Recommended Distance for Marathon Training?

The short (and unsatisfying) answer is yes, but also no.

When it comes to marathons, many recommend running a 20-miler at least once a week. However, some training plans actively condone 20-mile runs, with the most notable one being the Hansons Marathon Method.

Developed by elite running coaches Kevin and Keith Hanson, the Hansons Marathon Method essentially puts a 16 miler cap on its standardized training plans.

It limits long runs to 25-30% of the runner’s total weekly mileage, meaning that if you’re running, say, 60 miles a week, your maximum mileage in a single run is between 16 to 18 miles.

How Many 20 Mile Runs Before Marathon

According to the Hansons, breaking this rule puts you at a greater risk of injury, depleted muscle glycogen, and overtraining.

It’ll also make the following workouts subpar at best because you won’t be in your best state. You’ll be too exhausted to train at maximum capacity since you’ve depleted all your energy running over 16 miles several days prior.

But the Hansons Marathon Method is just one among thousands of marathon training plans available.

Running coach John Honerkamp neither advocates nor disapproves of 20-mile runs. Instead, he recommends capping long runs at 3.5 hours.

“There’s no benefit to running more than 20 miles before race day,” he said, “the risk of overuse issues or injury is simply too great to ignore.”

Still, Honerkamp states that you don’t want to run less than 16 miles or less than three hours when training for a marathon.

The goal here is to get your body used to being tired, and then ask it to run more. Pushing it even when it doesn’t want it—within safe bounds, of course.

Should You Really Include Long Runs In Your Marathon Routine?

Although doable, running a marathon without prior training is a bad idea. If you participate in a marathon blind, you’re basically asking for a one-way ticket to the hospital. It’s a punishing thing to experience without training.

Long runs make the grueling distance of a marathon more tolerable, which is why they’re essential to marathon training.

Here are some benefits of long runs:

Increase Your Mileage Capabilities

Long runs train your body to run for long distances.

They increase the enzymes in your muscle cells and the vessels that surround them, which in turn delivers more oxygen to working muscles.

This results in stronger muscles, ligaments, and tendons.

These adaptions increase your overall stamina and thus your capacity to run longer.

And as you develop great aerobic endurance, your body won’t have to work as hard to attain the level of performance next time.

Improve Muscle Strength

Running for prolonged periods of time doubles—and sometimes even triples—the strength of your leg muscles and connective tissues.

When you run for extended periods, your body taps onto your fast-twitch muscle fibers to assist with slow-twitch activities.

Using both these muscles increase the size and number of the body’s mitochondria (the powerhouse of the cell), allowing you to convert energy more efficiently.

Physically and Mentally Prepare You for the Run

Long runs allow you to physically and mentally prepare yourself for a marathon.

Think of them as trial runs; they give you the chance to practice fueling with carbs during your runs, and experiment with different speeds and pacing options.

They also give you the chance to test out many different kinds of fuel options, such as gels, sports, or energy bars, that work best on your runs. The last thing you want to experience during a 26.2-mile run is gastrointestinal issues and depleted energy because of the wrong fueling choice.

In addition, long runs give you the confidence to actually complete the race at a given time. These runs help you stay focused and mentally strong so you won’t hit a wall at some point during the run.

You’ll still be able to push through physical barriers even when your mind (not your legs) is telling you to stop. You’ve done this before—you’ve trained for this—so there’s no way for you to fail.

And if you face a challenge during the training, you’ll be able to adjust your routine so you won’t face the same difficulties during the marathon.

Make You Faster

If you’re a first-timer, you’re likely not concerned about crossing the finish line at a record speed. Completing the race is all that matters.

But if you’re a professional or simply want to improve your overall speed, long runs can help you achieve this goal.

As mentioned earlier, long runs improve your endurance. With this improved endurance, you’ll be able to hold a certain pace for longer periods of time. These runs train your body to switch between your slow-twitch muscles to your fast-twitch muscles when the former gets tired. 

5-Week Training Plan for Marathon for Beginners

Now that we’ve established how many 20 mile runs before a marathon, allow us to share our recommended training plan based on your experience level.

This first training plan is catered to individuals who have previously completed a half-marathon and now moving on to a full marathon.

How Many 20 Mile Runs Before Marathon: 5 week training plan

Here’s a summary of abbreviations used:

  • ER: Easy Run
  • LR: Long Run
  • CT: Cross-Training
  • ST: Strength Training
  • TR: Tempo Run
  • HR: Hill Repeats

With that out of the way, let’s start with week 1:

Week 1

  • Monday: 10 mile ER (at a pace of 4 to 5 RPE)
  • Tuesday: Rest
  • Wednesday: 30 minutes CT or rest
  • Thursday: 10 mile ER
  • Friday: Rest
  • Saturday: 5 mile ER
  • Sunday: 30 minutes CT + ST

Week 2

  • Monday: 10 mile ER
  • Tuesday: Rest
  • Wednesday: 30 minutes CT or rest
  • Thursday: 10 mile ER
  • Friday: Rest
  • Saturday: 12 mile LR
  • Sunday: 5 mile ER 30 minutes CT + ST

Week 3

  • Monday: 10 mile ER
  • Tuesday: Rest
  • Wednesday: 30 minute CT or rest
  • Friday: Rest
  • Saturday: 10 mile LR
  • Sunday: 30 minutes CT + ST

Week 4

  • Monday: 10 mile ER
  • Tuesday: 30 minutes CT + ST
  • Wednesday: 3 mile ER
  • Thursday: 16 mile LR
  • Friday: Rest
  • Saturday: 5 mile LR
  • Sunday: 30 minute CT or rest

Week 5

  • Monday: 10 mile ER
  • Tuesday: 30 minutes CT + ST
  • Wednesday: 5 mile LR
  • Thursday: 30 minutes CT or rest
  • Friday: Rest
  • Saturday: 3 mile ER
  • Sunday: Race day

5-Week 10K Training Plan For Intermediate Runners

This next training plan is dedicated to runners who have completed at least one full marathon in the past.

Runners of this level should be able to comfortably run up to 12 miles every other day.

Week 1 

  • Monday: 10 miles LR
  • Tuesday: 20 minutes TR + 2 HR
  • Wednesday: 30 minutes CT or rest
  • Thursday: Half-marathon race pace with three 4-minute intervals
  • Friday: Rest
  • Saturday: 30 minutes CT
  • Sunday: 5 miles ER

Week 2 

  • Monday: 15 miles LR
  • Tuesday: 30 minutes TR + 2 HR
  • Wednesday: 25 minutes CT or rest
  • Thursday: 10K race pace with five 4-minute intervals
  • Friday: Rest
  • Saturday: 30 minutes CT or rest
  • Sunday: 5 miles ER

Week 3 

  • Monday: 10 miles LR
  • Tuesday: 25 minutes TR + 3 HR
  • Wednesday: 30 minutes CT or rest
  • Thursday: Half-marathon race pace with seven 4-minute intervals
  • Saturday: 40 minutes CT or rest
  • Sunday: 3 miles ER

Week 4 

  • Monday: 20 miles LR
  • Tuesday: 20 minutes TR + 4 HR
  • Wednesday: 25 minutes CT or rest
  • Thursday: Half-marathon race pace with three 4-minute intervals
  • Friday: Rest
  • Saturday: 40 minutes CT or rest
  • Sunday: 3 miles ER

Week 5 

  • Monday: 5 miles ER
  • Tuesday: Rest
  • Wednesday: 20 minutes TR
  • Thursday: 25 minutes CT
  • Friday: Rest
  • Saturday: 30 minutes CT or rest
  • Sunday: Race day

5-Week 10K Training Plan For Advanced Runners

This training plan is for athletes and veteran competitors who can run up to 20 miles every other day. This is for people who’ve joined at least five full marathons and are looking to improve their PB.

Week 1

  • Monday: 15 miles LR
  • Tuesday: 25 minutes+ 2 HR
  • Wednesday: 30 minutes CT or rest
  • Thursday: Half-marathon race pace at three 5-minute intervals
  • Friday: Rest
  • Saturday: 40 minutes CT
  • Sunday: Rest

Week 2

  • Monday: 20 miles LR
  • Tuesday: 30 minutes TR + 3 HR
  • Wednesday: 25 minutes CR or rest
  • Thursday: Half-marathon race pace at four 5-minute intervals
  • Friday: Rest
  • Saturday: 40 minutes CT
  • Sunday: Rest

Week 3

  • Monday: 10 miles LR
  • Tuesday: 25 minutes TR + 3 HR
  • Wednesday: 40 minutes CR or rest
  • Thursday: Half-marathon race pace at three 5-minute intervals
  • Friday: Rest
  • Saturday: 40 minutes CT 
  • Sunday: Rest

Week 4

  • Monday: 20 miles LR
  • Tuesday: 30 minutes TR + 3 HR
  • Wednesday: 30 minutes CR or rest
  • Thursday: Half-marathon race pace at three 5-minute intervals
  • Friday: Rest
  • Saturday: 40 minutes CT or rest
  • Sunday: Rest

Week 5

  • Monday: 5 miles ER 30 minutes CT
  • Tuesday: Rest
  • Wednesday: 30 minutes CR
  • Thursday: 5 miles ER
  • Friday: Rest
  • Saturday: 30 minutes CT
  • Sunday: Race day

Conclusion

This concludes our article on how many 20 mile runs before a marathon!

If you’re a beginner, aim to run at least 16 miles two to three weeks before the marathon.

For intermediate runners, attempt to do at least one 20-mile run every other week.

Veteran athletes can safely run one to two 20-mile runs per week.

Good luck!