Posted by: Joe English | September 17, 2008

Training: What’s the longest run I should do in preparing for a marathon?

Coach Joe English

Coach Joe English

One of our readers sent in the following question that comes up a lot at this point in the season. The question was a lengthy one, but here is the portion that will give you the flavor of the question:

I am training for the Chicago Marathon and I am left with one long run in my schedule. I need your advice on whether or not I should try running a longer distance for this last run. Here’s the background on what I hope to achieve. . . .

My training started end of May and I’ve been increasing my mileage gradually, at about 2 miles per week. Since my last rest week, the long runs that I’ve been doing each week are 16, 18, 20 and 22 miles. I guess I have so far been able to recover from each long run to take on 2 more miles the following week. However, during the 22-mile run this past Sunday, my knees were hurting during the last 2 miles. The final 4 miles in the marathon will be very slow and painful if this happens (and I think it will).

I am unsure if I should go for 24 miles for my last long run or go for 22, 20 or even less. I wonder if doing 24 miles would help my legs handle that kind of stress better given that distance, or will I risk hurting myself by going so far.

This question boils down to an age-old one that is: how far do I need to run in my long runs to be ready for the marathon? The answer to this is one that every marathon runner should really know, but it requires an understanding of two related topics — tapering and recovery — to really be able to able to internalize it.

Just a week or so, I wrote a memo to my current team of new marathon runner trainees explaining these issues. In it, I explained that the longest run that I ever prescribe in training is 20 miles. The reason for this being that the recovery period from a training run of more than 20 miles is so extended — usually taking at least three weeks — that the risk of injury is outweighed by the slight benefit gained by running an additional 2-4 miles.

With that said, the follow on question is typically “how then do I go another 6.2 miles on race day?” This is the part that requires some additional background to understand it. The ability to jump that last 6.2 miles on race day comes from a combination of consistent training throughout the season and a prolonged recovery period at the end of the season — in which the exercise load is tapered down — to allow the body to fully recover from the training over the course of the season.

This combination of consistent training intensity over a period of time and then the recovery period of the taper allows the body to adapt and prepare for the new load that it is about to face on race day. That rest period is what allows the body to spring up to that 26.2 mark from the previous longest run of 20 miles done in training.

I know from your question that you’ll have doubts about this strategy. You say that the last few miles of your runs have been difficult and you think that those last four miles of the race are going to be impossible. But you have to keep something else in mind about your training runs: they are done in the midst of your training regime, without recovery, and without rest.

As I explained to my runners in an e-mail:

“. . .the 20 miler you do in training is very different than what you feel like on race day. The primary difference is that you are not in a state of rest and recovery when you go into it. Quite the opposite, you are at the end of your training week and have been training consistently for months or weeks. Because of this, the 20 miler can be tiring, perhaps even more tiring than the race itself in some ways. You won’t have the energy of race-day, the fans or the mental preparation. And, since you haven’t likely done a run or walk of that length before, you will be physically challenged just making it through it.

Why am I telling you this? Because, the last four miles or so of the 20 miler can be a pretty tough experience and often people come away feeling that “if I can barely do 20, how am I going to do 26?” It helps to go into these longest training sessions knowing that they are going to be difficult and that you will feel entirely different after we complete the process by giving you the recovery of your taper at the end of the season.”

So my bottom-line is to limit your training to 20 miles and make sure to do this 20 miler three weeks before your race. After that, settle in to a taper that allows yourself to recover and heal. Then you’ll be ready to tackle that last 6.2 miles.

Here are three other articles that you can read to get more preparation as you go into this phase of training:

First time marathon runner 20 miler anguish
How should I feel after running 20 miles in training
Should I do one or two 20 milers in preparation for my marathon?

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Coach Joe English, Portland Oregon, USA
Managing Editor, Running Advice and News



  1. I am a first timer. I have been working so hard and been very eager to run my first marathon in Detroit in October. Just recently I have had pain in my left knee (outside) I went to a PT and he said it is my IT band. I am so depressed. A mere 4 weeks away and I don’t know if I will be able to make it. I can’t run now and who knows how long it will take to heal. Will I make it? The longest run I did was 15 miles. HELP!

  2. Shelly,

    Sorry to hear abut your injury. I know how hard it is to get hurt right before a race.

    I’ve previously written about this topic. Read this article and then let me know if your question didn’t get answered:

    Good luck to you!


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