Think of your body as a car and the chemical reactions in the car’s engine as the metabolism.

Let’s say you went on a long Sunday drive. After you finish your Sunday drive you park your car and carried on with the rest of your day. You might think that the car is back to the same condition as it was just before you drove it, right? But guess what, the car engine is still hot and it will take some time for it to cool down (some say at least 30 minutes).

Your body and metabolism can behave in a similar manner. Your metabolism (or the chemical reactions in our body) can take a long time to “cool down” and get back to a resting state after an intense training session (Up to 48 hours). Have you ever wondered why that is?

We revisit our physical training as the two categories:

  • 1st low intensity longer duration training
  • 2nd high intensity shorter duration training

Now, a new note. The first one is Aerobic and the second one is Anaerobic.

Our aerobic system is being used to produce consistent energy for a long period of time (It can go for hours), but there is a catch. It’s able to work only at a low intensity and it requires oxygen to operate. So when you go for a long walk or easy jog, know that you are using primarily your aerobic system.

Our anaerobic system is used when our body needs a quick and great amount of energy for a specific task (If you are late to work and sprinting to catch the bus, you’ll understand what I’m saying). But you can do so only for a short period of time (up to two minutes) *1 before the need to reduce the intensity. And this system can do so without the utilization of oxygen. So when you do some sprinting, burpees, high intensity training or even sprinting to catch the bus, think of and thank this system.

The high intensity activities and training is primarily responsible for the after burn effect, and the thing to blame for that is the EPOC.

What is EPOC and What Has It to Do with Anything?

EPOC stands for excessive post exercise oxygen consumption.

Let’s say you joined an HIIT (in this case, high intensity interval training) class. Due to the type of


this activity, it is anaerobic system dominant. Because this system doesn’t require oxygen to operate, after your bouts of training your body enters what is called “oxygen debt” and in order to “pay” that oxygen debt, your body enters a Post Exercise Oxygen Consumption state. (Diagram from

Because of that, our metabolism stays elevated (and our engine stays hot) for a period of time before it gets back to its resting state.

Other things that contribute to EPOC and raise our metabolism:

  • re-oxygenation of oxygen stores in the blood and muscle
  • increase of body temperature after training
  • increase of the heart rate and breathing rate
  • recovery and repair of damaged muscle
  • increase of metabolism-boosting hormones
  • refilling of the energy stored that has been used during our training

The EPOC can last a few minutes, few hours or up to two days after your workout! It depends on the intensity of your workout. *2

One more thing to consider before you include High Intensity Training into your program and especially so that you can reap the rewards of the EPOC and the after burning effect. Don’t overdo it!

Because of the intensity of this kind of training, it puts a huge amount of stress on your body, and your body needs a sufficient amount of time to recover. Otherwise, you might get injured or feel burnt out.

So, for your healthy and well-rounded training program combine low intensity long duration training/aerobic training and High Intensity Training.  Moderation is the key…so definitely don’t overdo it!

I’m here to help you and support you in your fitness journey. Let’s make your fitness journey a reality and a success.

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Supporting Your Healthy and Active Life

Sam Jabarin
Canfitpro Personal Trainer
ISSA Nutrition Coach

*1 ISSA Nutrition the complete guide page 138

*2 ISSA Nutrition the complete guide page 144-146

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