The “20-mile” myth

The Hansons’ Marathon Method contains an interesting approach to training for the marathon. The idea of the traditional “20-mile run” is abandoned with the longest run being only sixteen miles in their plans. Within the book they explore and compare the recommendations of other coaches and plans.

The idea of the 20-22 mile run comes from the days of Arthur Lydiard in the 1960s when he had his middle-distance runners doing this distance every Sunday! It might sound hard but remember these were runners with the capability of racing four minute miles. They’d begin the season taking 2hr35 and slowly work down to completing the runs in little more than two hours – quicker than 6min/mile, but that’s typically the easy pace of a world class runner. I don’t know if it was deliberate to create a course this long or down to the natural geography of Auckland, running in the Waitakere mountain range where Lydiard lived.

Derek Clayton, the world record holder for the marathon through the 1970s ran 150-160 miles every week. It was his belief, and he put it into practice, that he needed to run a 25-mile run every Saturday to be ready for his marathons. It’s hard to argue with a man whose record stood for so long yet Clayton suffered injuries and needed surgery eight times. Very few, if any, modern elites would do this level of mileage regularly now. Although there’s no record of how long these runs took him, given his toughness and general mileage, it’s hard to believe they would have been run any slower than 6-min/mile therefore being completed in 2½ hours.

In Jack Daniels’ Running Formula book he states a Long Run should never be more than 25% of the weekly mileage. The problem with this statement is it suggests you have to be running eighty miles per week to train for a marathon which is unnecessary for all but the best runners. This 25% limit is better applied to his training plans for shorter race distances but even with the marathon he says don’t go over 2½ hours. He makes the point that for someone only running four times per week, the runs are automatically 25% of the weekly mileage!

The 20-mile run is actually an arbitrary distance, there’s no science to this number. In Europe where they work in kilometres the Long Run is often 30K or 35K which are 18.6 miles and 21.7 respectively. People love round numbers! Of course, it’s true that runners used to say “Twenty miles is the halfway point of the marathon” as a reference to when the body starts to hit the wall and you have to dig deeper, but it’s also because they rarely trained much past it so the body wasn’t used to longer runs.

The most interesting approach to the marathon long run is the one detailed in Steve Magness’ The Science of Running. Magness coached at the Nike Oregon Project under Alberto Salazaar, himself once a world-class marathoner. The training knowledge at NOP was of the highest calibre so this method is one used by some of the best runners in the world. The first two months of a training programme are used to build up the Long Run to the twenty mile mark but then after this, there’s rarely specific Long Runs scheduled. They’re replaced by workouts that typically total the mileage. A world-class marathoner running at 5min/mile might do a Tempo run of 15-miles taking 1hr15 and when you add in a 4-mile warm-up and warmdown the session totals twenty miles. US Marathoner Josh Cox demonstrates this workout in the Training Day video.


The Hansons believe your marathon should be based on good physiological principles. They conclude that running for significantly longer than 2½ – 3 hours doesn’t provide those benefits to runners. Certainly in my own limited marathon training, I used to find that a three hour run left me feeling dehydrated whereas I happily run between 2 – 2hr15 every Sunday without taking food or drinks and arrive home feeling fine.

Hansons may limit the Long Run to sixteen miles but they include a run of eight miles the day before which results in a total of twenty-four miles over the two days. As they describe it, those sixteen miles then become the “last sixteen miles of your marathon” rather than the “first sixteen” which runners who set off fresh legged typically do. This is a method called cumulative fatigue and is used by ultrarunners to train for their races which can be in excess of one hundred miles. On a training weekend they might run for 5-6 hours each day to enable them to compile a total closer to their race distance.


When I was marathon training because I was capable of a 22-min parkrun I could reach twenty miles in three hours, it happily coincided with my 9-minutes per mile easy pace. For a slower runner, I would look for them to improve their pace and to use the principles of cumulative fatigue to help them prepare for a marathon. I’ve met far too many 5-hour marathoners focused on reaching the mythical 20-mile run in training because that’s what the guys who were capable of running four minute miles in the Sixties did. The problem is, as they build up through fourteen, sixteen, eighteen, twenty miles they start tearing themselves down Sunday after Sunday with demoralising trudges lasting four hours or more, often in unpleasant winter conditions. Motivation sags, they can’t wait for the taper and end up walking large chunks of the marathon anyway. If you must build up to twenty miles get it done early interspersing the progression with less-taxing two hour runs on alternate weeks to give the body a chance to recover.


This far I’ve focused on the marathon distance but I find many runners don’t believe a Long Run is necessary for anything other than half or full marathons. This is a mistake and maintaining a weekly Long Run is an important part of building your aerobic base. By running further once a week you dig out muscle fibres that would otherwise lie dormant. Does it need to be 20-miles? Definitely not unless you’ve reached the capabilities of the Lydiard crowd.

Middle distance runners typically do a run of 10-12 miles and it goes up from there depending on the distance being raced and the runner’s capabilities. But it’s equally important to think in terms of time. I always aim for a minimum duration of 1½ hours for my weekly Long Runs and a maximum of 2½ hours. Of course, this distance needs to be in proportion to my other running, I wouldn’t do that if I were rebuilding after a layoff and only doing thirty minute runs the rest of the week.

Whatever your event, whether it’s parkrun, 10K or longer don’t neglect a weekly long run. It’ll keep you positioned to pick up on a half or full marathon at short notice while helping you get fitter and faster for your chosen distance.

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