Take the car for a long drive, and when you stop for a rest, the car’s engine is hot, right? As the vehicle is resting, the engine starts to cool down.
This is similar to how our bodies work.
After your workout is completed, your body will continue to burn more calories than if you were at rest. This effect is called “excess post-exercise oxygen consumption” (EPOC), and it occurs because your muscles are still working when they should be resting.
The amount of oxygen required to restore your body’s metabolic function to its average resting level is called homeostasis. After you’ve recovered, your body will burn calories to help repair itself.
The process by which our bodies convert food into energy is called metabolism. Metabolism takes food, breaks it down into smaller molecules, and turns those molecules into ATP, which is our body’s energy for muscle activity. We produce ATP either through aerobic pathways using oxygen or anaerobic pathways without oxygen. As we get more active, our body uses anaerobic pathways to burn stored ATP to continue working.
A proper warm-up is essential to use aerobic metabolism more efficiently. Spending five to eight minutes warming up will help you use your energy more effectively, making the workout more manageable and more productive.
Studies suggest that, as long as we continue to use oxygen during our workout, aerobic energy pathways will be able to provide most of the ATP needed for the training. When our exercise places a greater demand on the anaerobic energy pathways, it increases the need for oxygen after working out. This enhances the EPOC effect.
Here are 6 EPOC facts to know:
1.) Exercise that consumes more oxygen consumes more calories
A calorie is the energy it takes to heat 1 liter of water by 1-degree centigrade.
The body burns about five calories of energy to consume 1 liter of oxygen. This means that you can increase the amount of oxygen consumed during and after a workout to increase the number of net calories burned.
2.) What your immediate post-exercise oxygen is used for
Your body is doing the following during any recovery period:
- Producing ATP to replace ATP used during workout
- Resynthesis of your muscle glycogen from lactate
- Oxygen levels restore in venous blood, skeletal muscle blood, and myoglobin.
- Uses protein to repair damaged muscle tissue
- Restores body temperature to resting levels
3.) Circuit training and lifting heavy require ATP from the anaerobic pathways when using short intervals
Performing compound lifts, such as deadlifts and squats, or alternating between upper-body and lower-body movements will use more energy from your anaerobic pathways, leading to more muscle fatigue.
The increased need for anaerobic ATP will create a greater demand on our aerobic system to replenish that ATP during rest and post-exercise recovery.
The intense training load with a shorter recovery interval will demand more energy from your anaerobic system. This will lead to a more significant EPOC effect.
4.) High-intensity interval training (HIIT) is the most effective way to stoke the EPOC effect
Your body uses aerobic metabolism at high intensities more efficiently to produce ATP. However, anaerobic pathways can provide enough ATP if the energy is needed immediately.
High-intensity interval training (HIIT) works because the body produces ATP through anaerobic pathways, which can be depleted quickly. This is why HIIT is an excellent way to work out because it allows our aerobic system to produce the ATP we need.
An oxygen deficit is a condition in which the volume of oxygen consumed during exercise falls short of what would be needed if energy demands were met only through the aerobic energy pathway. This can lead to fatigue and pain in muscles.
5.) EPOC is influenced by intensity, not the duration of exercise
A higher intensity exercise requires ATP from our anaerobic pathways to occur. If the ATP necessary to exercise at a specific level of intensity isn’t obtained aerobically, it must come from the anaerobic pathways.
After completing a high-intensity interval workout, the body uses oxygen to restore glycogen and rebuild muscle. This enhanced EPOC effect is due to aerobic pathways replacing ATP consumed during the training.
6.) The EPOC effect from a high-intensity interval or strength training workout can add 6-15% of the total energy cost of that session
The high-intensity workout requires much more energy from the anaerobic pathways and generates a more significant EPOC effect, leading to vast post-exercise energy expenditure.
There is evidence that training with heavy weights and high-intensity interval workouts may result in a more significant EPOC effect than running or a lower-intensity circuit workout.