How long should your long run be in marathon training?

This is one of those great questions because the answer is ‘it depends’.

 It depends on your weekly mileage

 It depends on the fitness you are bringing into the training cycle

 It depends on your race goal

o Are you looking to ‘just finish’?

o Are you targeting an aggressive time goal?

o Are you looking to finish comfortably?

 It depends on your experience

 It depends on your injury history

 It depends on your ability to recover

 It depends on your race pace goal and your training pace

 It depends on your coach’s philosophy

 It depends on your psychology

It depends.

Why is the long run such an emotional topic in the first place? The long run really defines marathon training. The long run is, especially to outsiders, the measuring stick and the manifestation of marathon training. It is those long runs that make people shake their heads and say; “I don’t even drive my car that far!”

The long run is an emotional high water mark in your training plan. It is a status thing. You get to casually post to social media that you just finished a 20 miler and you’re going to take an ice bath.

Leading up to those long runs it stresses you out. Those long runs are like the white whales on your training plan. Sticking out there and taunting you. Keeping you awake at night in anticipation. What’s the weather going to be like? Do you have enough fuel? What are you going to wear? What time in the morning are you going to start?

You have to be careful the day before about what you do and what you eat. You lose most of that long run day getting ready or recovering. You ache from the effort for a couple days.

Each one of these long runs is a big deal, a big achievement and an emotional and physical stepping stone in your progress towards your goal race.

That’s why we care about how long the long run should be.

It the first running boom of the 1970’s someone decided that 20 miles was the right number for the long run. That number has been passed down through the generations as a given, a check list item. Did you get a couple 20 milers in? Good, you’re ready.

Why did the old timers decide 20 miles was the magic number? For a couple reasons. First, at the time, the average marathoners was training and racing at a 6-8 minute mile pace. That 20 miles translated to 2 ½ – 3 hours on your feet – which Is not a crazy number. Most of them were also peaking in the 50-70 miles per week range and this put the 20 miler at 30 – 40% of weekly mileage – which, again is not a crazy number.

Finally, the infamous marathon ‘wall’ where the body runs out of glycogen typically hit these runners around 20 miles in a race. For these runners 20 miles was a reasonable rule of thumb, and still is for runners that fit that description.

But, it is not the 1970’s and not all runners fit that description.

Do you need to get 20 miles to run a marathon? No. That’s an arbitrary number. I have had outstanding marathons with a 16-mile long run, understanding that the other elements of my training supported that race execution. I have had outstanding marathons where my long runs were 20, 22, 24 and 2 X 26! I have struggled in marathons with 30 and 50-mile long runs. There is nothing scared about the long run or about 20 miles. It all depends on your training philosophy and what you’re trying to accomplish.

What’s your race goal? What’s your experience?

Do you want to ‘just finish’ the race or do you have a time goal in mind? There is a big difference in the training you need to qualify for Boston and the training you need to get to the finish line. Depending on your race goal your training will be different.

As far as the long run is concerned a first-time marathoner, just looking to finish, may end up running longer long runs just for the confidence. Each successive long run is probably the longest time or distance they have run in their lives and is a confidence boost as they progress through their training.

A more experienced athlete might be better served using some of that long run time and energy to work on other aspects of training that impact their ability to race. The point being that they are not training for a long slow race. They are training to hold a hard effort well past their comfort zone. You tend to see more 10-12 mile tempo runs or step up runs to practice this race-specific effort.

If you’re trying to achieve a time, a long slow run is a very non-specific training activity and you may be better of spending that time and effort in training activities more closely aligned with your goals.

The other goal of the long run is to teach your body how to go beyond the wall. You use the long run to practice and become comfortable with your fueling and racing strategies.

In some of the original marathon training plans the long run was also a form of base-building. You need to tease that out of your training as well. Do you have a base aerobic fitness going in? Current plans will typically have you build that base as a first phase of your training, before you enter a race-specific training phase, and this, again takes some of the emphasis off of long runs.

Some of the current plans focus on cumulative stress instead of one long run. The actual long runs are shorter but they simulate the cumulative stress of racing a marathon by designing a number of hard workouts that week that lead into that shorter long run. The theory is that you still get the stress benefits of a long run by closing on tired legs without the time on your feet.

What’s your weekly mileage?

Weekly mileage is important when thinking about how long your long run should be. The higher your ‘normal’ weekly mileage is the less a shock to the system a long run is going to be. Most coaches will design a plan where the longest long runs are 30-40% of your weekly mileage.

This is for injury prevention. If you are only logging 25 miles a week, throwing in a 20 mile run is going to almost double your weekly mileage. This kind of stress can produce injuries.

What is your injury history? How fast do you recover?

If you have a history of injury, especially if those injuries tend to occur towards the end of a training campaign, lots of longer long runs may be a mistake. If you’ve been keeping a log you can look at where injuries happen.

Interestingly enough the overuse injury may not happen during the long run. It may not manifest for a couple of days. That’s what I find. You may notice it during or after that long run but it turns into something a few days later.

You also have to consider what your fitness level is and how fast you recover. If you’ve got a good base and no injuries you stand a better chance of weathering that long run stress.

Recovery tends to be specific to the individual. I know some ultra-runners who can do incredible distance week after week with no ill effects. It’s just how they are designed and the efficiency of their running.

I used to use the long run as a bit of a hammer when I was younger to get into race shape faster. Like cramming for a test I could do that long effort and recover from it to yield a benefit of a big fitness boost. I don’t recover as quickly now and it takes a couple weeks to get the pop back in my legs.

Your running economy and efficiency also makes a big difference. Small problems with your form or small weaknesses tend to get amplified when you go long and you fatigue.

My coach, and many of the heart rate based coaches does the long run by time instead of distance. He’ll give me a 3 hour run and maybe max out at a 3:30 run – which for me is going to end up being somewhere in the neighborhood of 20 miles ironically enough.

There is a new challenge those runners from the first running boom never considered. There is a new generation of runner that is much further back in the pack that didn’t exist. You have folks training for 5 or 6 hour marathons. If you do the math on there training pace a 20 mile run might be a 5 hour investment. That’s an enormous amount of time on your feet.

I frankly don’t have an appreciation for that. I did pace a friend to a 6+ hour marathon once and all I can say is that my feet were pretty sore. Spending that much time on your feet tends to produce overuse injuries.

I know Galloway has his runners do over-mileage for these plans. I think he has them do a long run of 28 miles which is mind boggling to me because it will take some of these runners 7-8 hours. That’s not a long run, that’s a short vacation. He is able to do this because the plans are very long – 26 weeks – the intensity level is very low and the ramp up time is incrementally slow.

What’s the right answer?

There is no universal answer to this question. As we said in the introduction; „It depends“.

As a general rule of thumb fitter, more experienced athletes will be able to handle longer runs as part of their training, but may actually choose to focus that energy on other training aspects that are more race specific.

Beginners and intermediate runners may end up with the traditional 3 X 20 mile rule of thumb in their plan and that will be enough to give them a fighting chance to go the distance.

Back of the packers may want to consult Galloway or one of the longer duration plans.

The way I look at it is that I’m training for a 20 mile run with a 10K race at the end. I’m trying to get to that 20 mile mark with my systems intact and my legs still under me so I can close that last 10k. That requires a special mix of endurance and race-specific fitness and execution. That balanced effort is my unicorn. And that’s what I design my training for.

Clearly there is no ‘right answer’ for every runner. How long your long run will be is up to you, your coach and your training plan. Lay all the factors out as you’re putting your plan together. Look at it holistically. Don’t be afraid to experiment.