The 20 Miler

There is a lot of debate about whether or not runners should include a run up to 20 miles in their marathon training. Some plans call for no 20 milers, some call for multiple. Some coaches and runners believe a 20 miler is too much while others swear by them. After training for the marathon, I can see both sides of the argument.

If you’re an experienced runner squeezing in 70-80 miles a week then a 20 miler probably isn’t even necessary. At the other end of the spectrum, if you’re a less experienced runner running lower mileage and find that the longer distance weekend runs in the training plan are resulting in the need for extra recovery time (and therefore, missed weekday runs), then the 20 miler probably isn’t very beneficial. If you’ve run multiple marathons, then you may be fine with just running 16-18 miles having completed enough marathons to know you can do it.


Then there’s those of us in the middle. I wasn’t running high mileage, but I also didn’t need extra recovery after my 20 and 22 milers. Maybe I didn’t need the 20 or 22 miler to successfully run the marathon, but I saw a lot of benefits from it. First there was the ever-famous “time on your feet” which I found to be mentally helpful and probably more so than physically helpful. Because my 22 miler was done at a slow, easy pace I only ran for about 7 minutes longer on marathon day than I did for my last long run. Going into the race, I knew my body was capable of staying strong for a long duration of time.

Another benefit was being able to really practice fueling. I had never taken more than two gels on a run and the 20 and 22 milers were my opportunity. I knew I could handle two, but what if 3 was too much for my stomach? What if I needed to take one sooner than every 5 miles? There’s no perfect formula and anything can happen on race day, but going into it knowing I had success with fueling on my training runs is always a good place to be.

A final benefit for me was the opportunity to test out my race day shoes. This may sound silly, but it really was the decision maker for me. After my 20 miler, my feet and legs felt pretty good. After my 22 miler, my calves were tight and sore in a way they hadn’t felt previously and I couldn’t imagine an extra 2 miles did me in. I decided to wear the heavier, more cushioned shoes I wore on my 20 miler instead of the shoes I usually wear for half marathons that I wore on the 22 miler. Had it been a cooler either day, it could’ve been a good opportunity to test out my race day wear as well.

I don’t think there’s a right or wrong when it comes to choosing whether or not a runner will include a 20 miler or not. For me personally, a 20 or 22 miler is something I would definitely include in my next marathon training cycle.

7 thoughts on “The 20 Miler

  1. This is such a great post because it’s such a big decision! I think the choice to do a 20+ miler is a personal one. I love hearing what people do, and why. The past two training cycles, I’ve gone up to 22-23 miles. My theory is no more than 3 hours of running (for me) before it gets too risky and I get into that diminished returns area. This is different for everyone. I’ve had a lot of success with 20+ because mentally, I know I can handle the distance.

    Moving forward, I am going to change things up. I believe in the 20+ miler, but I’ve been stuck in the same range all year with my races. I’ve run everywhere from 3:12-3:57 this year. In 2014, I never went over 20 miles and I ran 3:06, and hit sub-3:10 twice. However, I also ran 5 marathons that season, so it was like I was constantly doing a 26 mile long run. But in training, I never went over 15. So for Boston, I’m going to use Hansons. I’m doing a post on it. It means my long run will not be as long as I am currently used to, but the theory is that the cumulative fatigue will tire out my legs. Mentally, I do like having 20 milers under my belt but I am ready to try something new. I’m still trying to sell myself on the shorter distance run, though. I do agree with you that 20-22 has a lot of benefit!


  2. Hanna @ TheMillennialNextDoor

    I have ever-so-gradually been trying to move my training toward de-emphasizing the long run in favor of more weekly mileage and spreading out the miles a little more evenly throughout the week. I think most arguments for and against the 20+ are mental-preparation based, as most experts agree that you don’t get any additional physiological benefits after you hit the 2 hour mark but you do start to put yourself at greater risk for injury. That said, I will always incorporate at LEAST one 20 miler in my training, because I feel that this distance is the best to test out any fueling strategies and see how my body holds up past the 3 hour mark. I no longer incorporate anything longer than 20 as I don’t personally feel I get anything out of 22 milers that I could get out of a 20 miler, but I’m definitely team 20 miler.

    But, as they say, there are as many marathon training plans as there are marathoners. Live and let live.


    1. After running the marathon I honestly think a 18 miler is probably enough, especially if a training plan has a lot of speed work or other hard workouts, but again goals and training dynamics obviously play into that. That being said, I’d probably still include a 20 miler in my next training cycle because it’s fun with a group!


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