How to Use Intervals in Your Marathon Training (and Why You Should)

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On to the runs!

(are you new? If this is the first article you’ve seen, I thought you might like to know this is the 4th in our series of articles for training for a marathon. If you’d like to get the series from the beginning, click here to sign up and you’ll get an email every week with a new piece on a different aspect of marathon training.)

Did you know that one of the most common misconceptions around marathon training is that you just, run?

As in, a few times a week, do a couple short runs and one long run and that’s how you build up?

Actually, to train efficiently you want to be looking at 3 different types of run per week: intervals, tempo and long run.

Each one of those runs make a specific and important change in your physiology that allows you to run a marathon without collapsing into a puddle (hopefully).

Can you guess which type of run is the most often overlooked of the three?

You guessed it – the interval!

What Are Intervals?

First off, let’s talk about what intervals actually are. Simply put, intervals involve short-ish bursts of speed work, or fast running, with a short period of rest (i.e. a slower run) in between.

The 3M2M running guides recommend your intervals should be 2-3 minutes of speed, with 2 minutes of rest.

You can start with a 20-minute session (not including warm-up time) with 5 repetitions, increasing each week until you end up with 10.

The main thing to focus on is your effort level.

Aim for a perceived effort level of 75-80% of your max if you’re a beginner, and closer to 80-90% if you’re experienced. Assuming you’re happy with your 5K time, you can use that as a minimum pace (or slightly faster) for a guide pace.

What Does Interval Training Do?

Here’s the fun (and science-y) bit.

Interval training increases your VO2 max (which is the maximum rate that your body can take up oxygen to create energy). Your body needs oxygen to create energy for your muscles, so the more oxygen your muscles can take up, the longer you can work before getting worn out (assuming, of course, you have enough fuel as well – more on that in the nutrition post).

This means that your endurance gets better, and you’re able to perform at a higher pace for a longer period of time (along the lines of being able to run at a faster pace for 10 minutes instead of 5).

So you can run faster for longer, helping you towards a faster race pace and that all important PB!

Some Science

There are some great resources around the web that will tell you more about what VO2 max is and how interval training affects it, but this one in particular I found really helpful:

A group of researchers tracked 61 young adults randomly assigned to low, medium, or high intensity workouts and found that the high-intensity workouts increased VO2 max almost twice as much as the low-intensity training.

Click here to go to the full article: Effect of Intensity of Aerobic Training on VO2max

Intervals – Do Them Anywhere

Intervals are pretty portable.

You can do your intervals indoors on a treadmill, or outdoors if you prefer, on a running track or your local park. Just find somewhere flat and use a stopwatch or running app to track your time.

The main thing to focus on is the intensity and duration of each interval. Build up slowly, increasing the total number of intervals you do each week (up to your taper, of course).

If you’d like an exact interval plan, how to increase week to week during the last 3 months before your marathon, you can find a detailed training plan in our 3M2M First Marathon and Repeat Marathon running guides.

More About VO2 max:

How Important is VO2 Max? What Does Yours Acually Mean?

Why VO2 Max Is Important for Athletes

What is VO2 Max in Athletic Training?

This post is part of our 3m2m marathon training series. If you’d like to receive these straight to your inbox, click here to sign up and you’ll get an email every week with a new piece on a different aspect of marathon training.

This post has been drawn from our 3 Months to Marathon First Marathon Running Guide and Repeat Marathon Running Guide, by Katherine Creighton Crook with Michel Glendinning from Thrive Fitness. Click on the links if you’d like to purchase the guides, or click here to purchase from Amazon Kindle.

If you’d like to browse the 3 Months to Marathon range of packages including massage and PT sessions, you can visit

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