Between the prevalence of overweight and obesity and our general penchant to love to eat, most people love the fact that exercise burns calories.
For this reason, one thing that exercise physiologists and fitness professionals like to research and discuss is the number of calories you can burn doing different types of exercise.
For example, depending on your weight, a long 7-mile walk might burn 800 calories, a Hatha yoga class might burn 250 calories, and a heavy lifting session in the gym might burn 450 calories. But what about the calories you burn in EPOC?
But, what happens when you take off your walking shoes, roll up your yoga mat, and take off your weightlifting gloves? Do you immediately go back down to burning the baseline level of calories you burn at rest?
Not exactly.
Depending on your workout, your metabolism may remain elevated after the workout, meaning that you keep burning more calories than you normally do at rest.
This increase is termed excess post oxygen consumption, or EPOC for short.
You’re certainly not alone if you’ve never heard of excess post oxygen consumption or have only a vague understanding of it.
In this article, we will explain the EPOC definition, everything you need to know about excess post-exercise oxygen consumption, and how it impacts your metabolism.
We will cover:
- What Is EPOC?
- What Causes EPOC?
- Types of Exercises That Increase EPOC
- How Many Calories Does EPOC Burn?
Let’s dive in!
What Is EPOC?
Let’s start with a basic EPOC definition before we get into the nitty gritty details, exercises, and metabolism.
EPOC is short for excess post exercise oxygen consumption.
What it refers to is the elevation of your metabolism after exercise has stopped.
Essentially, when we exercise, the muscles need much more oxygen than they do at rest in order to generate the ATP (energy molecule for the cell) to contract and produce movement.
The more vigorous the exercise and the more muscle mass involved in the movement, the higher the oxygen demand.
In order to meet these oxygen needs, you start breathing harder and faster to take in more oxygen, and your heart pumps harder and faster to circulate more oxygen-rich blood to the muscles.
As a result, while you exercise, you are consuming more oxygen and burning more calories.
Again, it’s important to restate that the higher the intensity of the workout and the greater the percentage of your overall muscle mass involved (total-body exercise versus isolated movements), the faster and harder your heart rate and respiration rate, meaning the more oxygen you’re consuming and calories you’re burning above resting values.
Now, as soon as you complete your last rep with your dumbbells or hit stop on the treadmill, the muscles’ need for oxygen decreases significantly.
No longer are you asking your muscles to contract forcefully against a heavy squat, propel a powerful running stride, or crank the pedals against a bunch of resistance on your spin bike.
As a result, your breathing rate starts to slow down, and your breaths become more relaxed and shallow.
Your heart rate begins to drop from upper heart rate zones to a slower rhythm, and instead of contracting so forcefully that your chest nearly vibrates with each beat, you’d maybe have to palpate your hand on your chest or on a pulse point to be cognizant of your heart rate.
These relaxation responses of the cardiovascular system are due to the fact that your muscles don’t need as much fuel (oxygen)—they are “consuming” less oxygen, so you can “consume”—or take in—and deliver less oxygen.
However, just because you’ve stopped exercising doesn’t mean everything goes right back to baseline, or resting levels, right away.
Your heart rate and respiration rate remain somewhat elevated because your muscles continue to require (and consume) more oxygen after the workout has stopped.
Whatever amount of oxygen you’re consuming above your resting rates is your excess post-exercise oxygen consumption.
What Causes EPOC?
So we’ve explained in detail what EPOC is, but what causes excess post-exercise oxygen consumption?
Why does your metabolism remain elevated after exercise?
The short answer is that the muscles still need additional oxygen above baseline levels even after the workout is over.
But why? If your muscles are not working out anymore, why does EPOC happen?
There are a few contributing factors that cause EPOC, or this excess post-exercise oxygen consumption for the muscles.
According to research, the following oxygen-consuming processes take place during EPOC:
- Producing more ATP to replace the muscle stores of ATP used during your workout.
- Resynthesizing muscle glycogen from lactate.
- Restoring oxygen levels in myoglobin and hemoglobin.
- Returning body temperature to baseline levels through sweating and increased cutaneous circulation.
- Removing metabolic waste products from the muscles.
- Beginning the repair process of muscle fibers by shuttling amino acids to the muscles and assembling proteins.
Additionally, your heart rate and respiration rate remain elevated after your workout has stopped, mainly to continue taking in and delivering the extra oxygen your body still needs.
However, these processes in and of themselves (faster heart rate and rapid breathing) also contribute to EPOC because they are energy demanding, so they burn calories and require oxygen.
Types of Exercise That Increase EPOC
Almost any type of physical activity can cause at least a little EPOC, but the higher the intensity of the workout and the more muscle mass involved, the higher the EPOC.
For this reason, high-intensity interval training (HITT) results in a greater EPOC, and potentially a higher overall calorie burn, than moderate-intensity steady-state cardio.
Here are a few takeaways in terms of maximizing EPOC from exercise:
- Workout intensity matters, not duration: A short, hard workout, even potentially a 4-minute Tabata workout, will result in a higher EPOC than low-intensity workouts like walking or yoga, even if the low-intensity workout is long.
- Total-body workouts increase EPOC: Isolation exercises do not increase EPOC as much as total-body workouts.
- Short, intense anaerobic efforts increase EPOC: Vigorous, anaerobic efforts like heavy lifts, plyometrics, short sprints, and all-out bursts of exercise followed by brief periods of rest elevate EPOC because, during the brief rest intervals, the aerobic energy systems have to resynthesize ATP used for those anaerobic efforts, which is often a losing battle. Therefore, after the workout is over, ATP, glycogen, and myoglobin have to be resynthesized.
Examples of workouts that would increase EPOC include the following:
- Jumping rope with bouts of 30 seconds hard, 15 seconds easy
- Total-body circuit training
- Plyometric exercises like box jumps, depth jumps, jump squats
- HIIT-style training, whether running, cycling, swimming, rowing, lifting weights, etc.
How Many Calories Does EPOC Burn?
EPOC results in an elevated metabolic rate, meaning you burn more calories over your baseline resting metabolic rate (RMR).
In fact, for every liter of oxygen consumed, the body burns approximately 5 calories.
Unfortunately, unless you have access to indirect calorimetry equipment in an exercise physiology lab, it’s difficult to accurately measure the calories burned from EPOC.
However, evidence suggests that the EPOC caloric expenditure from exercises like HIIT workouts and high-intensity resistance training usually comprises only about 6-15% of the net total oxygen cost of the workout.
In other words, if you burn about 500 calories in a workout, only about 30-75 calories will be burned as a result of EPOC.
The best way to estimate the number of calories you burn during EPOC is to continue wearing your heart rate monitor after your workout is over.
You can stop the time after the workout and save your data. Then, restart the watch and allow data capture for the recovery period.
Once you notice your heart rate has returned to resting levels, you can stop your watch.
Note that the number of calories your fitness watch reports that you burned will not be your EPOC; this number will represent the EPOC calories and the resting metabolic rate (RMR) calories.
If you really want to get scientific and as precise as possible in your EPOC calorie estimations, you would then need to subtract your RMR calories, though this is not easy.
To determine the number of calories you would have been burning anyway, just resting, you would have to divide your daily RMR by the length of time you ran your watch to capture EPOC (how long it took for your heart rate to return to baseline).
For example, if it took one hour, divide your RMR by 24 and subtract that number from your calories burned.
You can estimate your RMR, or even your entire daily caloric expenditure, with online calculators.
Alternatively, the Mifflin-St Jeor Equation can be used to calculate RMR and is considered to be accurate within 10% of the measured resting metabolic rate.
The Mifflin-St Jeor formulas for each sex are as follows:
Men: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) + 5
Women: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) – 161
Ultimately, EPOC doesn’t result in a ton of extra calories burned, but hey, every little bit counts. So, push yourself and crank up that workout!
For some of our high-intensity training workouts, check out our HIIT training for runners!
