Doing a 20 mile long run when training for a marathon has been the method that all new, and many veteran marathon runners have used for years. But what if I told you that old research with modern updates shows a very different picture of optimal training performance?
I’ve coached many runners through marathons and I am going to explain in this post what I explain to them before working together to create a plan.
If you’d rather watch this breakdown, you can check out the full video here:
For everyone else, let’s get stuck in. This post will cover:
- What your body needs to do to cover a marathon.
- Why Doing Long runs will build or break your confidence.
- Why Doing Runs over 3 hours is not physiologically beneficial.
- The most beneficial plan you could have to get the most out of your marathon, based on your ability.
(P.S. I will be talking in miles during this post. If you prefer kilometers, 20-22 miles is 32-35 kilometers.)
What your body needs to be able to do to cover a marathon
In the most simple terms, to cover the distance you will have to run around 35-45 thousand steps. This is going to require a lot of energy, a good level of aerobic fitness and strong resilient muscles.
If you’ve done a marathon before, you will know the effort and even struggle that it takes to get over the finish line. The training is tough, both physically and mentally, you have to sacrifice a lot to fit everything in. Training takes its toll, and can be demoralizing when you have to fit a long run in around work, family and social time. It’s hard knowing that if you don’t put the time in- those 35-45 thousand steps are going to be some of the most difficult you will ever take.
But what is the most optimal way? Is there a better way than fitting a 4-5 hour run in, at 5am on a bitterly cold Sunday morning?
Why Doing A 20 Mile Long runs will build or break confidence
A lot of the time a runner who is new to marathon running, or doesn’t do them regularly at least, wants to be able to do a 20-22 mile long run to prove to themselves that they can do the distance. This can be good or bad.
If you’ve ever trained for a marathon you might have first hand experience of doing these long runs. What did you feel? If you haven’t done one before, how much easier do you think running 22 miles on your own is compared to doing 26.2 amongst hundreds or even thousands of people?
I’m honest when I explain this to my athletes: 22 miles on your own is as hard as doing a full marathon during a big event. It will push you both physically and mentally just as hard. If you use this run as a make or break test and you fail, you will be broken before you even start on the big day… especially if it is your last long training session. I have seen it before multiple times- it’s hard to break down that block once it’s there.
So on one side you have the lack of confidence over the distance, on the other you run the risk of it going from an unknown to a straight ‘I can’t do this’. Even when you do finish the 22 mile long run, there is always a creeping doubt. 22 miles after all is 4 miles short and really tough in its own right.
Why Doing Runs over 3 hours is not beneficial
A marathon will take 95% of people more than 3 hours, so logically you would think that you need to do training runs longer than 3 hours… but science says otherwise.
A study as far back as 1982 found that mitochondrial adaptations (which is code for the boost in your aerobic endurance) offer diminishing returns the longer you exercise. It proved that your positive adaptations were more stimulated in the early parts of exercise.
This research was then built on in 2017 during a study in Canada. This study suggested that the benefit of longer duration training is stronger at moderate and high intensity. Showing that extending your long run even further at low intensity provides a weaker adaptation stimulus.
These studies show that doing a couple of really long runs up to your marathon is probably going to be less physically developmental than you think. Maybe doing more shorter runs will help? What about doing the longer runs but at a higher speed based on that second study? Or just go with that really long one still…
Well there have also been studies into the impact that these really long runs have on your muscles. In 2017 research was done into the stress that marathon runners put on their body. It was found that inflammation and muscle damage remained high for over a week following the event. Supporting the fact that doing runs that extend into the 4 hour mark and beyond become a breaking down event that have a negative impact on any training that you might then do in AT LEAST the week afterwards.
When put together these studies suggest that going over 3 hours will have diminishing returns on the physical adaptations that you will gain as well as negatively impact what you do for the next week or more. Going past 3 hours becomes a game of risk to reward. Increased chance of injury for a lesser adaptation? Or increased confidence you can do the distance vs being tired for the next week?
The most beneficial plan you could have to get the most out of your marathon
Now, after coaching many athletes, some still want to do the longer runs of 20-22 miles to prove to themselves that they can do it and I am OK with that. A marathon requires a lot of mental grit as well as physical strength. I still offer them these longer runs and provide training plans with them included.
And speaking of which, I provide detailed training plans for all the different methods of marathon training we’re about to cover. So, if you have an upcoming event and want a professionally written plan or coaching, check out our Marathon Training Plans.
Here are a few ideas that you could implement into your training based on the time you have and your ability.
The First Idea: Keeping the Long Run
If you still want the really long run involved in your training to help prove to yourself that you can do it, the longest run that you would optimally have is a MAXIMUM of 3 hours.
This would mean:
- At 8 Mins per Mile (5 Mins per KM): Your longest run is 22.5 miles (36km)
- At 9 Mins 40 per Mile (6 Mins per KM): Your longest run is 18.6 miles (30km)
- At 11 Mins 25 per mile (7 Mins per KM): Your longest run is 16 miles (25.7km)
If you tend to run faster than this, I would keep the limit at 22.5 miles. The fatigue you will put through your muscles is going to have more of a negative effect than positive!
The Second Method: The Double or Triple Medium Run
This is one that I have started using more recently. Instead of focusing one day around a really long run, having multiple days back to back of medium distance runs is a great way to get the maximum training effect of the early aerobic stimulus that I mentioned earlier as well as giving your body a chance to recover and remain strong for every training day.
- For a double long run: I would prescribe 2 days of back to back 90 minute runs (these would typically be at the weekend so one on Saturday and one on Sunday). I would also occasionally add 2×20 minute efforts at your target pace to the second day to increase your body’s lactate shuttle and your perception of effort under fatigue.
- For a triple run: I would recommend 3×60-75 minutes spread over 3 days. Again this is optimal for increased training stimulus and can be done at a slightly higher intensity. I usually suggest, including a warm up and cool down, making the third run a marathon target pace effort. The idea, like before, is to give you a perception of your target pace under fatigue, just like you will have on race day.
Because of the reduced stress on the body, these double or triple days can be done multiple times throughout your training to give greater adaptations.
The double or triple is personal preference. Personally I prefer the 2×90 as it fits into most people’s schedule better.
Why Smarter Beats Longer
So, what does this all mean? It means we need to shift our thinking from ‘surviving the distance’ to ‘training for performance’. The goal isn’t just to prove you can suffer for 22 miles in training. The goal is to arrive at the start line in the best possible shape, recovered and injury free. You will then give yourself the best chance of a successful marathon, whatever that may be to you.
Be Efficient, and stop running too far!
