Excess Post-Exercise Oxygen Consumption - 6 Things You Should Know
Have you ever gone on a long road trip and when you arrived your car's engine was hot? As it sits there, it starts to cool down to a resting temperature.
That's not rocket science to understand that, but this is the same thing that happens in our bodies after exercise.
Once your workout is over and you are back into your daily routine, your body's metabolism will continue to burn more calories than when you are at a complete rest. This physiological effect is called excess post-exercise oxygen consumption.
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This is the amount of oxygen required to restore your body to its normal, resting level of metabolic function. This is called homeostasis.
This is why your body burns calories after you've exercised.
Your metabolism converts nutrients from the food we eat into adenosine triphosphate, or ATP. This is the fuel that our body uses for muscular activity. We produce ATP either with oxygen, using aerobic pathways, or without oxygen on anaerobic pathways. As we start exercising, our body uses anaerobic energy pathways and stored ATP to fuel activity.
This is why a proper warm-up is important — spend five to eight minutes so you can use aerobic metabolism more efficiently.
Studies suggest once you sustain a steady-state of oxygen consumption, aerobic energy pathways will be able to provide most of the ATP needed for the workout. When our exercise places a greater demand on the anaerobic energy pathways, it increases the need for oxygen post-workout. This enhances the EPOC effect.
6 Things to Know About EPOC
1.) Exercise that consumes more oxygen consumes more calories
Did you know that a calorie is the amount of energy it takes to heat 1 liter of water 1-degree centigrade?
The body expends about five calories of energy to consume 1 liter of oxygen. This means when you increase the amount of oxygen consumed both during and after a workout can increase the number of net calories burned.
2.) This is what your immediate post-exercise oxygen is used for
Your body is doing a few things in our 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
Whenever you perform compound lifts or perform a circuit alternating between upper and lower-body movements will place a greater demand on the trained muscles for ATP from your anaerobic pathways.
This increased need for anaerobic ATP will create a greater demand on our aerobic system to replenish that ATP during rest and post-exercise recovery.
Using heavy training loads with a shorter recovery interval will demand more from your anaerobic energy. This is what yields a greater EPOC effect.
4.) Studies suggest high-intensity interval training is the most effective way to stoke the EPOC effect
We produce ATP more efficiently through aerobic metabolism, but at higher intensities when the energy is needed immediately, your anaerobic pathways will provide enough ATP.
This is why we cannot perform high-intensity exercise for a long time. We simply can't produce enough energy. The reason high-intensity interval training works is because the ATP is produced through our anaerobic pathways. Once that ATP is depleted, it needs to be replenished. Our rest interval or active-recovery period during lifting allows our aerobic system to produce the ATP we need.
An oxygen deficit is the difference between the volume of oxygen consumed during exercise and the amount that would be consumed if energy demands were met only through the aerobic energy pathway.
5.) EPOC is influenced by intensity, not duration of exercise
Higher intensity exercise requires ATP from our anaerobic pathways. If the ATP required to exercise at a specific level of intensity isn't obtained aerobically, it must come from the anaerobic pathways.
After a high-intensity interval workout is over, our bodies uses oxygen to restore muscle glycogen and rebuild muscle. Our body will use the aerobic pathways to replace ATP consumed during your workout, which enhances this EPOC effect.
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
A high-intensity workout requires a lot more energy from the anaerobic pathways and generate a greater EPOC effect — leading to extended post-exercise energy expenditure.
Training with heavy weights and high-intensity interval training workouts have been suggested to be superior to a steady-state running or a lower-intensity circuit workout for creating an EPOC effect.