Long runs are an inevitable part of marathon training, and even plans that have “shorter” long runs still include them. But that raises the question, how far should your longest run be before your marathon?

 

20 miles or 3 hours?

The general rule of thumb is to run 20 miles in your longest run, and to make this run the last run before you begin tapering. Often people like to run 21 miles as a way to conquer the big 20.

Another commonly accepted concept is the idea of running for no more than 3 hours. The theory is that you won’t recover well enough from anything over 3 hours, meaning you’ll not be in the best shape for your marathon 2-3 weeks later.

 

Combining both ideas

The recovery aspect of the 3 hour rule does make a lot of sense as an upper limit for most marathoners, but there is a drawback. Let’s assume you’ll run at least 26.4 miles in your marathon between weaving around other runners and not being on the “racing line”.

In 3 hours a 3:30 marathoner could run 22.6 miles, and a 4 hour marathoner would reach 19.8 miles based on running at marathon pace.

If you’re running a 4:15 marathon however, you’ll only reach 18.6 miles, even at race pace. 

By referencing the 20 mile guideline, you can see that if you’re running a marathon in over 4hrs 15 minutes, then the 3 hour rule doesn’t necessarily work to prepare you for the race.

 

More than 3 hours?

If you’re looking at 4hrs 15 or more, I’d seriously consider doing things a little differently, running two longer weekend runs. This could be 2 hours on Saturday, then finishing off the remaining miles on Sunday to reach 20 miles across the two runs in the final week. It’s not ideal preparation, but it should give you better recovery than running in one stint and reduce injury risk as well.

 

More than 20 miles?

As I mentioned earlier, some people like to go beyond 20 miles in their training. I think a key bit of context to consider is the predicted marathon time they’re aiming for. The faster you are the quicker you’ll cover 20 miles, and with a high likelihood of faster recovery rates as well, then there’s an opportunity for running a little further.

It has been said that running a full marathon in training is the best preparation for your race, with the idea behind it being that it gives confidence and builds mental strength. Whilst it can work, it’s certainly not something I’d recommend for most people. It would have to be very slow to allow you to recover enough before your race, and the thought of having to run X number of minutes faster than you just did to reach your goal is more likely to destroy confidence than build it. Mental strength is a huge factor in marathon success and a good area to focus on to help with marathon running, but there are less physically effortful and risky ways in which to do this.

 

As ever, there are no hard and fast rules, but remember that the body can only recover so much within your taper. Whether you’re working with 20 miles, 3 hours or another strategy, enjoy that final long run before the big day and know that the hardest part is now done.

Written by Kyle Brooks, Running Coach based in Norwich, Norfolk