Everything you need to know about run energy systems

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Explaining the Aerobic, Anaerobic and ATP systems

Whether you’re just starting out or you’re a seasoned athlete, understanding how your body fuels your runs is key to optimizing your performance. In this blog post, we’re going to break down the different energy systems that power your runs, and give you some tips on how to train each one to become a better runner.

Energy Systems Explained

Before we dive in, let’s talk about what we mean by “energy systems.” Essentially, your body has three different energy systems it uses to power your runs. The first is the ATP-PC system, which is used for short bursts of activity, like sprinting. The second is the anaerobic system, which kicks in when you’re working at a high intensity and your body can’t get enough oxygen to your muscles. The third is the aerobic system, which is what you use when you’re running at a moderate intensity and your body can get enough oxygen to your muscles.

Fueling Your Runs

We now understand what the energy systems are and what they do. We also know that food is important; from “good fats” to simple and complex carbs all the way to protein timing. Yes, it gets confusing quite quickly.

But how are these energy systems fueled? In car analogy terms – what gas/petrol does each one need to perform its best?

The aerobic system uses a combination of glycogen and fat, which is broken down into fatty acids.

The anaerobic system uses glycogen, which is stored in your muscles and liver, and is broken down into glucose.

The ATP-PC system uses stored ATP and creatine phosphate in your muscles.

BONUS – Want to know more about the fuel? We talk more about foods and timing of said foods for running in the below links;

Training Your Energy Systems

Now that you know what your body is using for fuel, let’s talk about how to train each energy system. If you want to improve your short sprints and power, you’ll want to focus on training your ATP-PC system. This means doing short, high-intensity intervals with plenty of rest in between. Try doing 10-15 second sprints with 2-3 minutes of rest in between.

If you want to improve your ability to work at a high intensity for longer periods of time, you’ll want to focus on training your anaerobic system. This means doing longer intervals at a high intensity, with shorter rest periods in between. Try doing 30-60 second intervals with 1-2 minutes of rest in between.

Finally, if you want to improve your endurance and ability to run longer distances, you’ll want to focus on training your aerobic system. This means doing longer, slower runs at an easy to moderate intensity (2-4 out of 10 on the effort scale). Try running at a pace where you can still hold a conversation (ie: speak full sentences without gasping for air), but you’re starting to feel a little bit of effort.

For you exact data pace nerds – this would be between 60 seconds – 2 mins per km (or 90 seconds – 3 mins per mile) slower than your current 5k pace fitness.

Putting It All Together

So, now that you know how to train each energy system, how do you put it all together? The key is to vary your training so that you’re working all three energy systems. This will help you become a more well-rounded runner, and will give you the ability to run at different intensities and distances.

Try incorporating one or two high-intensity workouts per week to train your ATP-PC and anaerobic systems. These could be sprint intervals, hill repeats, or tempo runs. Then, do one or two longer, slower runs per week to train your aerobic system. These could be recovery runs, long runs, or even just a leisurely jog with a friend.


Understanding how your body fuels your runs is key to becoming a better runner. By training all three energy systems and varying your workouts, you’ll be able to run faster, longer, and with more efficiency. So, lace up your boots (errr super shoes?!), hit the road, and have fun!

What You Will Learn

  • The importance of aerobic base building
  • What ATP actually is
  • How to utilise anaerobic training to help you at the end of races
  • What energy systems are used when you train at Vo2 max and threshold
  • And a bunch more!

Episode Highlights and Timestamps

[02:59] Our latest training report

[06:03] Sandwich analogy of threshold

[09:43] The goal of threshold

[11:14] Breaking down the “burger” to the basics

[13:02] Focus on the aerobic base

[16:00] Fueling the aerobic system

[17:41] Why man is the most efficient species in covering long distances

[18:44] Defining the aerobic level

[24:25] The ATP system

[27:25] Can you add a heartbeat when getting older?

[29:44] Building aerobic and anaerobic bases for different runs

[32:50] Common mistakes for new runners

[34:15] Fun fact about the ATP system

[37:58] Developing the lactic system

[39:30] The Cooldown: Would you rather be healthy or fit?

[43:52] Maffetone method


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This episode is brought to you by NRG – Coaching which is Mike Trees’ coaching service. Mike coaches beginners to pros and all levels in between.

No one is too fast and no one too slow. They just want a desire to learn and improve.

They focus on 1,500m to marathon running and triathlon training.

NRG Coaching is constantly overbooked, so Instagram and this new podcast venture, gives Mike and the rest of his NRG coaching team a way to reach out to more people.

Contact mike and his team NRG-COACHING.com for more info

Original Music Used Here