Your Comprehensive Guide to Long Runs in Marathon Training

Female runner wearing running vest and sunglasses

Long runs are the “bread and butter” of marathon training. Getting them right is essential to having success in the marathon distance.

As part of a comprehensive training plan, the long run provides you with the necessary physiological adaptations to prepare to run 26.2 miles. Easy-paced long runs allow you to build aerobic endurance week after week, as you work up to the longest run of your training cycle which will be completed about 3 weeks before your marathon.

But just how long should those long runs be, what’s the best pace and what happens if you miss one? Consider this your essential guide to completing long runs in marathon training where I’ll cover these questions and more so you can get the most out of each and every one.

What is considered a “long run?”

A long run in the simplest terms is just your longest run of the week. But for most people, these are typically at least 60 minutes long and may go up to 3.5 hours or longer.

For beginner runners who are perhaps training for a 5 or 10k may have a long run that only goes up to 5-8 miles. But as a marathon runner, your long run will quickly advance into double-digits, perhaps even getting up into the 20+ mile range.

Benefits of the Long Run

When you have to run a marathon that extends the distance of 26.2 miles, it doesn’t take a rocket scientist to see why including long runs in your training is necessary. In fact, most people probably just do the long run and don’t question it because it’s on the training plan and seems to make sense. But do you actually know what’s happening in your body when you do those long runs?

Every time you run aerobically, or at an easy pace, you are building your aerobic endurance – or the length of time you can run without moving into an anaerobic (without oxygen) state. In other words, the better your aerobic endurance, the longer you can run without stopping. And my favorite part? Improved aerobic endurance also makes you faster!!

Physiological Benefits

Even though you can’t see it, long runs allow you to become stronger from the inside out. Here’s what’s going on inside that amazing body of yours:

  • New capillaries – those teeny, tiny blood are growing in number every time you run, and a long run gives even more opportunity. More capillaries means more paths for your oxygenated blood to get to your working muscles!
  • Stronger heart – your heart is a muscle, too, and every time you do cardiovascular exercise, you make it stronger. And a stronger heart is better able to efficiently pump blood (oxygen) to the rest of the body.
  • More mitochondria (energy!) – These cell powerhouses increase in number as you become consistent with your aerobic running. ISSA Online writes, “The overall density of mitochondria in muscle tissue increases in response to aerobic workouts.” And that means more energy for your muscles to continue to be able to function well as you run.
  • Muscular adaptations – When you run long, you’re giving your body more time on your feet to strengthen the ligaments, tendons, bones, joints and muscles.

Completing your long runs at an easy effort will allow these physiological adaptations to occur over time. So even though it may be daunting to see a 20-mile long run on a marathon training plan when you’ve only just begun, just know that putting in the work of all those training runs (long runs included) your fitness is improving with every step and trust you’ll be prepared.

What about psychological benefits?

I can’t forget to mention the confidence boost you get every time you complete a long run just a bit further than the last – that part’s a big deal, too! Also, the mental fortitude required to get through long runs will pay dividends on race day. Being strong mentally is what is going to push you to the finish line when the marathon gets tough.

RELATED: What is the hardest mile of a marathon?

How often should you do a long run in marathon training?

Long runs are typically completed once per week on the same day each week, but some people will find more success on a 10-day schedule.

Completing Long Runs Once Per Week

For most runners, completing a long run once per week will work best for both scheduling and endurance-building purposes.

Typically this long run is scheduled on the same day each week – for most people this works best on a Saturday or Sunday simply because of the amount of time it takes to complete the long runs as they get longer through marathon training. But not everyone has a typical 8-5 Monday – Friday work schedule, so pick the day that works best for you. However, I suggest that it always be the same day every week. This helps with planning, accountability and ensuring you’re giving your body the proper amount of recovery time in between.

A 7-day cycle just makes sense for most people because that’s how life is already structured. For most runners, this is the route you’ll want take.

Completing Long Runs on a 10-Day Training Cycle

Typically completing a long run every 7th day will bring the best results, but that’s not true for everyone. The following groups of runners may want to consider completing a long run every 10th day:

  • Older runners in the Master’s Category
  • Injury-prone runners
  • Runners with a schedule not conducive to fitting in a long run once per week

Essentially, following a 7-day schedule is often easier scheduling-wise, but if you have the flexibility to complete a long run during the week every other week, then you can follow a schedule that has you completing a long run every 11th day.

Here is an example of a long run schedule on a 10-day cycle:

Week 1:
Sunday: Long Run
Monday: Recovery Run
Tuesday: Rest
Wednesday: Quality Session
Thursday: Recovery Run
Friday: Medium Long Run
Saturday: Recovery Run
Week 2:
Sunday: Quality Session
Monday: Recovery Run
Tuesday: Rest
Wednesday: Long Run
Thursday: Recovery Run
Friday: Rest
Thursday: Quality Session
Friday: Recovery Run
Saturday: Easy + Hills

And so on…

If you’ve been used to a 7-day schedule this will definitely take some getting used to, but some find it just fits into their lifestyle better and helps them stay consistent without feeling overwhelmed by a weekly long run. If you struggle with accountability or don’t know how to properly create a marathon training plan but still want to follow a 10-day cycle, it may be in your best interest to hire a coach who can help you.

RELATED: Should You Hire a Running Coach? 6 Reasons Why

What pace should my long runs be?

The best pace for most long runs is your easy pace.

This means that your long run is done at around a 3 on a rate of perceived exertion scale and you should be able to hold a conversation. If you measure your heart rate, an easy run is completed in Zone 2 at less than 75% of your max heart rate. And if you know your 5k race pace, it should be at least 2-3 minutes per mile slower than that.

Long runs should be completed at an easy, conversational pace or a 3 on an RPE scale.

One of the biggest mistakes runners make is running their long runs too fast. For whatever reason, runners get in their heads that the only way to run their marathon goal pace in the marathon is by running that same pace in their long runs, but THAT IS WRONG!

Just because marathon pace isn’t like as fast as a track workout, it’s still a hard effort. And as we discussed in our article What is 80/20 running? Using Polarized Training to Your Benefit, mid-to-hard-intensity running should only be done for around 20% of your mileage.

Which means MOST of your long runs should be completed at an easy effort, and for a beginner marathon runner ALL of your long runs should be done that way.

Running for a long period of time is considered a hard effort in and of itself, which means you make it doubly-hard (that’s the scientific term lol) when you run them too fast. In all seriousness, this makes it very hard for your body to properly recover and you’re likely going to get injured.

Slowing down is just one of seven recommendations I give in my article, “Building Running Endurance for a Marathon.”

And by the way, it’s a misnomer that running slow in training will keep you slow in your races. In fact, it’s the opposite. My recommendation for those long runs? Embrace the saying, “Go slow to go fast,” and you’ll be amazed at your fitness gains with consistent work over time.

Other Types of Long Runs

More experienced runners may consider implementing these two types of long runs into their training as they get beyond the base-building phase of marathon training:

  • Fast-Finish Long Run -A fast-finish long run, also sometimes referred to as a “long run with a close” simply means you end the long run with some speed. This is typically the last 20-30 minutes or 2-3 miles of the long run and you should aim to get progressively faster during that portion until the end of your run. Ideally you’ll get down to marathon pace or faster, but even just putting in a harder effort at the end of your long run will help simulate the end of your marathon when you have to push the pace on very tired legs.
  • Long Run With Pacework – There are lots of variations of workouts that can be completed inside a long run. These are often prescribed as a runner gets closer to their marathon taper in order to adjust to running marathon pace while running a lot of miles. However, these can be extremely tough workouts, so they should only be done by runners who have already completed a few marathons and are already very comfortable with high mileage long runs.

    If you want to give it a try, a simple yet effective one is: 3-5-mile warm-up, 3 x (3 @ marathon pace with a 5-minute recovery jog between), cooldown.

Just remember to be intentional when completing these types of long runs in your training. They should NOT be done every week. Even the most advanced runners need to have opportunities to complete long runs at an easy pace to build their aerobic endurance. Because after all, the marathon is about 97% aerobic (more on that here).

What should my longest run be in marathon training?

Jack Daniels, famed running coach great, writes in the fourth edition of Daniels’ Running Formula, that long runs should never be longer than 2.5 hours long. Greg Mcmillan, another running coach great, suggests that runners complete a long run that is equivalent to their predicted marathon time and up to 4.5 hours, depending on their speed (he lays out his full advice here).

For fast runners who are capable of running a marathon in less than 3 hours, it makes complete sense to max your long run out around 2.5 – 3 hours, and even those running a 3-4-hour marathon will probably do great maxing out their long runs at 3 hours. But for those runners who will take 4.5 hours or longer, it will likely be difficult to feel fully prepared by only running a 3-hour long run. I typically suggest around 3.5 hours with perhaps closer to 4 hours for younger runners who aren’t injury prone.

Will everyone run a 20-mile or longer run in marathon training?

It doesn’t make sense for every runner to run at least 20 miles in marathon training.

We are so used to seeing 20-mile long runs on marathon training plans that they seem like they are absolutely necessary. But the truth is that is going to require a slower runner to be on their feet for a very long time if they are running at their easy pace like they should be. The risk outweighs the reward at a certain point.

So, who should run 20-mile long runs?

If you can run a 20-mile long run at an easy pace in less than 3.5-4 hours, then it’s likely best to complete if you’ve stayed healthy through all of your shorter long runs. Otherwise, cut your run off when you hit the 3.5-4-hour range and call it good no matter what mileage you are at.

For a deep dive in this specific topic, here’s a video from my YouTube channel:

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Remember that TIME ON FEET is ultimately the most important factor in preparing you for the race day mileage.

How many 20+ mile long runs should I run before a marathon?

This is a common question because for whatever reason, runners think getting to 20 miles will magically make them ready to run 26.2 miles, when that’s just not how it works. For some experienced runners, completing 3-5 20+ mile long runs in marathon training is the best preparation. For those less experienced, that could be a quick recipe for injury and overtraining.

Each runner is unique and comes to marathon training with a different running background and personal profile. If you are new to running I suggest you find a beginner marathon training plan that is written by a running coach (like this free one I wrote) and plan to follow what has been laid out for all long runs, including any 20-milers. However, if any of those long runs are taking you longer than 3.5 – 4 hours to complete, it is in your best interest to cut them short knowing that’s the best training for YOU.

When should I run my longest run before my marathon?

The longest run of a marathon training cycle should be completed just before the taper (where training volume and intensity are reduced) begins.

Most runners do best with a 3-week taper and should therefore run their last long run exactly 3 weeks before marathon race day. But if you have always run your long runs on Saturdays and your marathon will take place on a Sunday it is perfectly fine to complete your long run about 3 weeks before race day.

Others prefer a shorter taper, in which case your longest run might take place 2 or 2.5 weeks prior to race day (though this method is best for more experienced marathon runners or those working with a coach.)

What happens if I miss a long run in marathon training?

It’s inevitable that something is going to come up in your life that makes it difficult to complete a long run or two as scheduled. Whether that’s an illness, personal emergency or just a day that’s gone awry…we all have that happen from time-to-time.

It’s important to remember that your race day performance is not based on any one particular run or workout in training, but is instead a culmination of every piece of work you put in leading up to the marathon. So if you end up missing a long run, it’s typically not a big deal.

RELATED: A Guide to How Much Mileage Marathon Runners Run

In many situations it’s best to just move on and only look forward with your training – especially is the missed run was completely unexpected.

However, if you know something is coming up that you know is going to prevent you from doing your long run on your typical day, you can often move things around within your schedule so that you can get it completed on a different day. Just be mindful that you aren’t doing another hard effort the day before or after your long run. These situations is when it’s often very helpful to have a coach to guide you to do what’s best.

What should I eat before and during long runs?

Fueling your body appropriately during marathon training is incredibly important for having the energy required to get through your long runs. This is a huge topic, which is why I have two separate posts to ensure you know exactly what to eat before your long run as well as all the details on how to fuel during so you’re prepared for marathon race day.

Want to take your endurance-building to the next level? So many runners skip the Medium Long Run, but adding another 90 – 120-minute effort to your training can help you improve even more in your next marathon training cycle. Read all about it: The Power of the Medium Long Run in Marathon Training

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Marathon Running Tips & Tricks

New videos posted every Sunday. Watch them while recovering from your weekend long run!

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