Energy System Development 101

Updated: Jul 14, 2021

What are energy systems?

Let's keep this nice and simple.

Your body has to create energy to do things. In our case, we're talking about athletic movements such as running, sprinting, jumping, tackling and so on.

There 2 types of energy systems - aerobic and anaerobic.

Aerobic basically means creating energy with oxygen. Anaerobic means creating energy without oxygen.

The anaerobic system can then be broken down into 2 systems. We'll call them the anaerobic glycolysis system, and the ATP-PC system.

To summarise:

1- The aerobic system.

2- The anaerobic glycolysis system.

3- The ATP-PC system.

Each energy systems is always working, but 1 tends to dominate. You can see from the table in the below, how these systems interact for a 2 minute effort.

If you were to sprint as hard as you possibly could for 2 minutes, the ATP-PC system would work the most initially, it would then start to fatigue and your pace would slow. The anaerobic glycolysis system would step up as the main contributor. Somewhere between 40 and 60 seconds, the aerobic system is likely to take over (where you will see another drop off in speed). This system will work for hours or even days. Obviously, if you were going to run a marathon, you would never start like this, so the systems would act a little differently, but you get the gist.

Most people are pretty good with the first 2 (aerobic and anaerobic glycolysis) but miss the 3rd and end up just training the aerobic system even if that's not the goal. I see people consistently turning things into a grind to build "mental toughness" and all that nonsense.

If you want to get better over the long term, have a goal with your training and stick to it. What energy system are you trying to develop today? Does your training reflect that?

A well-rounded athlete develops all 3 energy systems and specialises in 1 or 2 depending on the sport.

It's not enough to simply smash one system, day in and day out. For most team sports this is counterproductive and increases your risk of injury come game day (not to mention increases the likelihood of a subpar performance).

So how do we train these systems? The rest of this article aims to answer the question.


The aerobic energy system is most active for efforts lasting more than 1 minute. Think 10km run. It's the energy system we use at rest (hence why it's even important for strength and power athletes to give it some attention).

This energy system creates the most amount of energy and is very efficient in that it doesn't cause many fatiguing by-products like the other systems. It's what allows us to run marathons and get to the end of footy games. It's what most people spend their time training.


This system can recover really fast so we tend to train it by having equal or less rest compared to work time. This means if we were to do 5 x 3 minute intervals we would want to have 3 minutes or less rest. There is a difference between aerobic capacity and aerobic power.

To increase total capacity you're better off doing longer intervals with shorter rest or continuous efforts i.e. 6 min on, 2 min off x 5 or a 10km run. For aerobic power you're looking at intervals closer to 1-2 minutes with 1-2 minutes rest. With both systems the entire session should usually go for at least 30 minutes.


The anaerobic glycolysis system is most active for efforts lasting between 10 and 60 seconds. Think 400m sprint. This energy system creates a decent amount of energy but fatigues relatively fast.

It's why you can't keep running faster at the end of a 400m sprint. Waste products like hydrogen ions build up in the muscles and cause dysfunction which reduce our speed and intensity. This system recovers slower than the aerobic system and actually needs help from the oxygen system to come in and filter out some of the junk that's built up.


When training this system we want to do intervals under 1 minute (for the most part). And have more than that amount of rest.

Let's keep it simple and say at least double the amount of time you worked for. So if you were doing 30 second intervals, have at least 1 minute off.

One of our favourite time domains for this system is the 15 on, 45 second rest protocol. 10 on 50 off also works well. We like to do 5-10 intervals of this, have a rest for 2-3 minutes and then do it again. When you see quality drop off, add more rest or end the session.


The ATP-PC system is the most explosive but fastest fatiguing system. It's most active for efforts lasting less than 10 seconds. Think 100m sprint. This energy system creates the least amount of energy but produces it extremely fast. It's what we use for heavy lifts, short sprints and explosive movements like jumping.

This system won't cause a burn like the other anaerobic system, but it might cause an athlete to feel flat. They'll lack that spark to repeatedly perform max efforts. This system needs 3-5 minutes to fully recover. This system is trained the least for most athletes - which is a secret weapon for your performance if you can train it properly. Unfortunately most people turn it into conditioning.


We want to work at roughly a 1 to 10 ratio. i.e. a 5 second effort should result in at least 50 seconds rest.

The goal is MAXIMAL intensity!

You shouldn't feel super gassed at the end of these sessions. Keep the quality high and the rest long. We like to do 6-second efforts every minute for 10-15 minutes. When the quality drops, end the session.

Air bikes and hill sprints are our favourite modalities for this.

Hopefully this hits home with you and will help you fill some of the holes in your training. If you take away one thing from this article make it this - Don't turn everything into conditioning like most athletes. Make sure you know the WHY behind the session and stick to it.



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