It’s Thursday evening here in Australia and I’m sitting here listening to my new favourite song of the month, Theory of a Dead Man – Medicate and I’m in the mood for research. I’ve been to the gym today and surprisingly I was not very hungry when I finished my workout. In fact I was anything but hungry. I decided to head straight home from the gym and rest for a bit to unwind and see how I felt later on in regards to replenishing my energy. Like clockwork, roughly half an hour after working out, I was absolutely starving! I mean, I ate before the gym, I had my protein intake but why the hell do I get so hungry after the gym? Well, let’s take a look at a contributing factor. You may have even heard of this term being thrown around the gym or with your fitness pals, EPOC (Excessive Post-exercise Oxygen Consumption). What the hell is that you ask? Well, lets delve into it:
EPOC, also sometimes referred to as Afterburn or Oxygen Debt, is best described as the replenishment of your fuels post exercise anaerobic/aerobic expenditure. Basically, after you have strenuously worked out you have exhausted [mostly] all the fuels and energy your body has to offer. So naturally, your body will need to restock the shelves. Think of it like a car, you fill it up (fuel), drive it hard (exercise) and then when you stop your engine stays warm (EPOC) until it cools and is ready for the next drive. Consider your cars service the rebuilding of the muscles stronger and better than before.
EPOC specifically brings your body back to Homeostasis (your bodies resting state) after repairing and adjusting to the exercise you have performed. It’s during this time your body begins to balance its hormones, replenish burnt fuel, repair nerves, rebuild muscle by replacing the building blocks to make them stronger and adjusts your creatine levels, utilising increased metabolism for fuel along with a lot of other systems working in conjunction, this is also called replenishment of Adenosine Triphosphate (ATP). It’s during EPOC that fatty acids are broken down and released into your blood stream and your replenishing fuel is turned back into more Free Fatty Acid stores. This state of post exercise has been studied to show the effects of increased metabolism immediately after exercise up to 36 hours post exercise.
A study by Purdue University in Indiana, found that participants in a controlled study utilised the effects of EPOC more during post exercise doing high intensity anaerobic exercise compared to aerobic exercise of equal workload. Studies also showed that intermittent exercise utilised greater use of EPOC than continuous exercise output but that in general, regular exercise at high intensities is going to result in even greater use of EPOC in our bodies post exercise. This means do more supersets and rest less between sets / exercises. EPOC appears to be triggered best by intensity of workout not duration.
You’ve probably heard that our bodies will burn calories even after exercise, well this is the system your body is using to do that function. Rest days are still going to be beneficial as your body is still burning calories even when you aren’t working out. Remember, our bodies are very sophisticated and don’t run on a watch like we do, our bodies are always working regardless of what we are doing. Superset your exercises and take less rest between sets to really utilise EPOC. Introduce new ways to trigger EPOC like resistance training and cardio. Remember, it’s not duration it’s about intensity so work harder not longer.