Marathon Training: Is The 20-Miler Necessary?

BY Hal Higdon

The 20-miler is an absolute necessity if you want success as a marathoner. You need to condition your muscles to keep clicking for whatever length of time you will be on your feet during the marathon itself.

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Is the 20-mile long run necessary—particularly if you are a back-of-the-pack runner not likely to finish faster than 5 or 6 hours? I understand that I will need to be out on the course for that length of time in the actual marathon, but running 20 miles in training forces me to lose time which on weekends could be applied to other activities. I’ve read recently that if you run three-and-a-half hours in practice, you get all the benefits of running long.


Let me make myself perfectly clear: Yes, the 20-miler is an absolute necessity if you want success as a marathoner. There seems to be a trend lately for some coaches to dumb down the training process, but I don’t agree with them. They claim that three-hour long runs are enough. They claim that you can split long runs, doing 12 miles in the morning, 8 miles in the afternoon, even split long runs for two days under the theory that total mileage is what counts. I understand their motivation. They want to make marathon training more accessible for people with busy lifestyles and simultaneously limit the injuries that often accompany overtraining. But I fear for runners who shortcut the training process, then try to navigate those closing miles unprepared.

There are several reasons why a 20-miler or two or three in training are important for marathon success. First, my scientist friends tell me that it is not until 15-16 miles (or 25 kilometers) that the true training benefits start to kick in. You need to condition your muscles to keep clicking for whatever length of time you will be on your feet during the marathon itself. Equally important, you need to figure out what fuel works best for you, not merely before the marathon, but during: to and through 20 miles. The same goes for shoes and clothing. Because we are all different, you can’t figure these details out by reading a book, not mine nor a book by any other coach. You learn during the last several miles of your long runs. And at the risk of stating the obvious: the psychological benefits of running 20 miles and touching, if not hurdling the wall probably outweigh the physiological benefits.

Does every marathoner need to do 20-milers? At the Tallahassee Marathon recently, I had a conversation with a runner who runs a marathon a month, a dozen in a year. He told me he never runs further than 14 miles in practice. Well, of course. His regular diet of monthly marathons provides him with 20-milers in the middle of his 26-mile races. But his was a special case and the large majority of runners doing marathons will benefit by making 20 their numerical training goal. 

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About Hal Higdon

Hal Higdon is a Contributing Editor for ‘Runner’s World‘ and author of 34 books, including the best-selling ‘Marathon: The Ultimate Training Guide’. He ran eight times in the Olympic Trials and won four world masters championships. Higdon estimates that over a quarter of a million runners have finished marathons using his training programs, and he also offers additional interactive programs at all distances through TrainingPeaks. Hal uses TrainingPeaks to power his interactive marathon and half marathon training plans — check out more of Hal Higdon’s training plans on his website.