What Are The Three Energy Systems - Level 3 simple explanation

What are the three energy systems?

What are the three energy systems? – Simplified Level 3 Explanation

You need to know about the three energy systems as part of your Level 2 and Level 3 Anatomy and Physiology exam, and also to truly understand the planning of exercise and get great results with your clients.

It’s is important to know about it, yet so many trainee fitness professionals leave this to one side because the manual makes it sounds too complex.

So, let’s keep it simple:

What Are The Three Energy Systems - Level 3 simple explanation

What are the three energy systems?

We have three systems in our body and they each create ATP under different environmental conditions.

These three systems are going to be represented by three sandbags in this video. Just ignore the numbers on it, but left this one’s red and therefore we are going to use that as Aerobic. This one is blue we are going to use that as lactic acid system and then the purple is going to be Phosphocreatine or sometimes known as the creatine phosphate System.

What do the Three energy systems do?

These three energy systems are working all the time in our body to create ATP so that we can move, so we can live, so our organs can function, and that happens all the time for all three of them. However, when do specific exercises, with a specific demand on our body, as a result we will rely on one more than another.

Creatine-Phosphate System: 

Let’s say for example we did something explosive, let’s say we are sprinting really hard or we are lifting something for just one repetition we would use our phosphocreatine system, which lasts for 10 seconds maximum

Lactic Acid System: 

If we have this intermediate time, this is 10seconds all the way up to 3mins we would use our Lactic Acid System, so that could be a 400-meter run, it could be something whereby you are doing a set of resistance training for 12 reps, thats probably in the 10 seconds to 3 mins which is lactc acid.


We spend most of our time Aerobic, Im Aerobic now, Your probably Aerobic Listening to this. So, as a result, this Aerobic system gets used for anything that’s three minutes plus, and this is where we use it predominantly.

But just remember we are using all 3 all of the time Sometimes people find it very hard to understand the Energy Systems because its so tiny it’s hard to imagine that our body.

So what we need to do is drop your comment or your questions below this video about anything to do with energy systems so we can help you understand it better.

To test your knowledge scroll to the bottom of this blog for 3 Quiz Questions all about Energy Systems:

Before you start learning and revising, it is best to find out where your knowledge is right now. For this, we have prepared 101 mock questions for you to download. These are mapped to the Active IQ Level 3 Anatomy and Physiology exam and other awarding bodies, so you know it is a clear reflection of your current ability. We have divided the 101 mock questions into sections so you can clearly see which areas are your stronger and weaker areas of knowledge. DOWNLOAD THE 101 MOCK QUESTIONS HERE 

If you are struggling with understanding what are the three energy systems, as well as other parts of your anatomy revision then join 6500 learners who have passed their exams with confidence using our Level 3 Anatomy and Physiology Revision Mastery Bootcamp.

Energy System Mock Questions:

[NOTE: The answers are below the 3rd question]

1.Which Energy System lasts for a maximum of 10 seconds in duration?
A) Creatine Phosphate System
B) Lactic Acid System
C) Aerobic
D) Type 2b

2. Which Energy System would be used predominantly in a 1-mile swim?
A) Creatine Phosphate System
B) Lactic Acid System
C) Aerobic
D) Anaerobic

3. Which exercise/sport will use the Lactic Acid System mostly?
A) Power Lifting
B) 400m Sprint Race
C) Marathon
D) Discus Throwing

Download More Mock Questions for FREE just link these by clicking this link: MOCK QUESTIONS


Mock Question Answers

Question 1= A, Question 2 = C, Question 3 = B

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