Ask the coach: Is 18 miles enough in marathon training?

On the 24-week marathon plan, the longest run is 18 miles. I’m wondering if 18 miles is enough to get me around my first marathon (Brighton marathon) next spring?

Rebecca

Running coach answer: The longest run in a marathon training plan

The distance run is more based on time on feet rather than distance covered.

In general, the maximum time for long runs in the development of endurance is between 90 minutes and two and a half hours. This allows for the development of capillarisation, the development of mitochondria, and fat-burning efficiency for energy use during exercise.

Anything significantly more can be counterproductive if it causes fatigue that prevents, probably, the most important training factor, which is the frequency of training. This time-on-feet rule changes if you are training for an ultra, where you will do longer runs, but more slowly, and get used to continuing after the critical point in most ultras after 35 miles. The marathon depends a lot on aerobic capacity and developing the ability to run near the threshold for a long time, ultra running, much less so, and is more concerned with fuelling to keep going at a more conservative pace.

There is a case to be made for the occasional longer run in a marathon build-up, to bring in the psychological factors of confidence in the ability to do the distance in the race, but from a physiological point of view, the changes to your running efficiency will have been built by runs of, let’s say for a marathon runner, 2 to 2.5 hrs.

The marathon is an anomaly from a psychological point of view, as it is, for most, the first event distance that you will not, or seldom, cover the event distance in training. Even elite runners seldom run the race distance. I would run a regular 20 to 22 miles, but I was able to do that in 2 hrs, 2.10 mins, and have enough held back to go out (twice) every day of the week.

Most of the runners I coach, who have target times of 3hr+ will not run more than 18 to 20 miles, and not do that very often, yet make progress in their PBs, because they follow a structured plan with good frequency of training.

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