Marathon Interval Training

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Interval training is a key tool in any good marathon runner’s toolbox.

It is a super-effective form of speed work, based around the idea of running in several short, fast bursts, with slower recovery intervals in-between.

There are many different forms of interval training, such as Fartleks, Yasso 800s, HIIT, hill sprints, and dozens of variations.  

But they all follow the same core rule of fast and slow intervals.

In this post, first I’ll look at the benefits of interval training, then I’ll explain why interval training is so beneficial for marathon runners.  Then I’ll run through how to apply interval training to your marathon training schedule.

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The Benefits of Interval Training

Why should you consider including interval training in your marathon training schedule?

Here are the main benefits:

1.Interval training increases your base speed.

Looking to improve your marathon finishing time?  

Interval training, like other forms of speed work, is specifically designed to make you faster.   

2.Interval training improves your stamina.

Running short bursts at high intensity improves your VO2 Max, or your aerobic threshold.  

For distance runners, this basically means your running economy is improved – you can go further for longer without burning as much fuel.

3.Interval training doesn’t over-stress the system.

One of the perils of marathon training is that over-training and fatigue can lead to injury. 

Running for hours on end wears you down.  

Interval training provides an alternative – a short, intense burst of exercise.   More on this below.

4.Interval training breaks up the monotony of marathon training

Prospective marathon runners run the risk of getting bored plodding around the park at 10km/hr.  

Interval training is a small shock to the system; it tells your legs to wake up, get engaged, and prove themselves! 

It prevents you from developing the ‘marathon shuffle’.

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The Importance of Interval Training For Marathon Runners

The second biggest mistake (after number one) most new marathon runners make is in their training.  

There is the assumption that the best way to prepare for a marathon is to go out for long runs at your desired marathon pace. 

This is wrong!

Going for long, fast runs is an ineffective way of preparing for a marathon.

In fact, it’s much more likely to lead to injuries and over-training.   These runs are usually done too slow to improve your speed, but too fast to really improve your stamina.

Instead, the best way to prepare for a marathon is in being specific when it comes to your training.

There are two main traits to develop:

Stamina and speed.

Stamina is developed in your regular training runs, and in your long, slow runs.

Speed is developed through specific speed work, and interval training is the old favourite of marathon runners worldwide.

Related: Progression Runs Guide: Ramp Up Runs + 4 Progression Workouts To Try Out

Marathon Interval Training 1

Different Types of Interval Training


Fartleks, as weird as they sound (it’s Swedish for “speed playing”), are the most basic form of interval training you can find.

Fartleks are essentially free-form interval training.  

You can run fast for a few hundred yards, then if you get tired, jog until the next tree.   They’re unstructured, and designed to be fun and engaging – instead of just going for a monotonous training run, fartleks will have you sprinting then jogging and breaking things up.

Related: The Incredible Benefits of Sprinting

The problem many marathon runners have with Fartleks is that they are simply not structured enough ; it’s hard to quantify the improvements made when running Fartleks if there’s no target pace or number of repeats.

Yasso 800s

Yasso’s, or Yasso 800s, were designed by Burt Yasso, a veteran runner and writer.  

Yassos are designed to give you a target pace, which also acts as an indicator of what your finishing time will be on your marathon.   

In recent years, runners have questioned whether Yassos should be considered a training staple, or simply a tool to indicate what your final marathon time could be.  

I find them to be a very effective way of introducing speed work; although they are best done on a running track.

Here’s how to perform Yasso 800s:

1. Take your target marathon finishing time and convert it into minutes and seconds.   So if you’re looking to run a 3hr 45 minute marathon, this would be 3 minutes and 45 seconds.   This becomes your target time for running 800m.

2. Start your workout with 5 – 10 minutes of light running and warming up.

3. Run 800m at your target pace.

4. Recover by jogging gently for the same length of time (3 min 45 seconds in this example).

5. Repeat as required.   I’d recommend starting with 4 intervals and building up to a maximum of 10 intervals at the peak of your marathon training.

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Shorter Intervals – 200 / 400m

Shorter intervals of only 200m and 400m are common in training plans for 5k and 10k races, but less so in longer distance runs such as the marathon.

However, I’d advocate for incorporating short sprint-style intervals into your training if you truly want to move the needle on your speed and really improve your marathon finishing time.

With shorter distances of 200m and 400m, you can do you speed work at a near-sprint, and recover with the same distance in very gentle jogging.

This approach really activates your legs and challenges your VO2 max – i.e. your aerobic ability – in ways which most other speed work doesn’t.

For doing shorter intervals, I typically stick to 200m fast / 200m slow, and repeat this 10 – 15 times. For the fast intervals, I simply run at a near-sprint – a speed which I can maintain for the 200m distance, but couldn’t maintain for 300m+.

Design Your Own Intervals

There are a myriad of different ways to structure your interval training. Different running coaches will make difference interval plans, depending on the runner’s ability and goals.

With this in mind, here’s some tips for designing your own interval training workout:

1. Don’t make the fast intervals longer than 800m / 4 minutes.

The whole idea of the fast intervals is to push your body to run at speed for a brief period.

If these intervals are too long, you’ll either burn out, or slow down to avoid burning out.

Limit the fast intervals to a suitable length – I recommend no more than 800m, or 4 minutes

2. The slow intervals need to allow you to recover, but not stop.

I typically find that making the slow intervals the same distance as the fast intervals gives you sufficient time to recover.

If that feels too easy, run slow for the same length of time as you ran fast. So if you covered your fast interval in 2 minutes, run slow for 2 minutes.

3. Get a good GPS watch.

Training on a track is ideal for intervals.

However, sometimes we have to make do and do interval training in the streets, parks, or trails.

If you’re in this situation, make sure you have a good GPS watch that accurately measures distance and speed.

4. Use landmarks instead of being too precise.

I find that using landmarks such as lampposts, corners, or shops is much easier than trying to track things precisely using my GPS watch.

In the park near my house, I run intervals around landmarks which I know the rough distance between; for me, this is good enough.

I also like that I can actually see the finish line; like when I say I’ll sprint to the fountain, I know what I have to do.

5.Start with low reps, but add every time.

Start off doing four repetitions of the interval if you can, but the next time you go out, do five. Every time, try to add one more repetition.

Have you incorporated interval training into your marathon plan?

Let me know how it’s going below!

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Thomas Watson is an ultra-runner, UESCA-certified running coach, and the founder of His work has been featured in Runner's World,, MapMyRun, and many other running publications. He likes running interesting races and playing with his two tiny kids. More at his bio.

6 thoughts on “Marathon Interval Training”

  1. I have joined my local club who run speed sessions… this takes the effort of planning out of the equation and my commitment is to just turn up. They mix it up with some weeks being sets of 200 and some at 400 or 600 but they are usually totally about 3.5-4K ( with the option to not do so many sets on the way out for the less fit/newby’s). I have found my weekly tempo runs and longer runs are getting easier at the tempo pace… I guess my body is adapting for the better! Roll on Athens marathon!

  2. Hi there, I’m confused after reading this article and this other one (
    Do you recommend Yasso 800’s alike intervals but your colleague does not? I am targeting a sub-3h marathon and I usually do 800m intervals in my anaerobic zone but now I am unsure if I should do longer (1200m-1600m) intervals at threshold zone, or a little of both short and long intervals. My Tempo runs are already done at steady and near threshold paces from 30-75min. I’d appreciate any insights you could give, I enjoy your content very much. Thank you!


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