EPOC – Metafit’s jewel in the crown

Burn fat in your sleep with Metafit! The 30-minute class that lasts 24 hours! The HIIT workout that keeps on working! These are just some of the claims that Metafit loves to make but what exactly do they mean and are they true?

I love Metafit. It’s by far my favourite workout. In under 30 minutes you can have an intense workout that burns fat, boosts metabolism and improves strength, speed and cardiovascular fitness. It is one of the quickest ways to improve your overall fitness and for beginners, if you’re committed and work hard three times a week, you can easily start to see real results within 6-8 weeks. So what is it about this short workout that makes it so successful?

The answer is simple: EPOC.

Excess Post-exercise Oxygen Consumption (also referred to as the “afterburn” effect) is an increased rate of oxygen intake following strenuous activity. Essentially, our body uses more oxygen after exercise than before exercise, and we expend more calories during our recovery from exercise than we do before exercise, even at rest. EPOC is the amount of oxygen required to restore your body to its normal resting metabolic function called homeostasis.

Your metabolism is how your body converts the nutrients you consume in your diet to adenosine triphosphate (or ATP), the fuel your body uses for muscular activity.

Here are seven important points about EPOC and how it can help you achieve optimal levels of calorie burning from your workouts:

1. During the immediate post-exercise recovery period, oxygen is used for the following functions:

  • Production of adenosine triphosphate (ATP) to replace the ATP used during the workout,
  • Re-synthesis of muscle glycogen from lactate,
  • Restore oxygen levels in venous blood, skeletal muscle blood and myoglobin,
  • Work with protein for the repair of muscle tissue damaged tissue during the workout,
  • Restore body temperature to resting levels.

2. Exercise that consumes more oxygen burns more calories.

The body expends approximately five calories of energy to consume one litre of oxygen. (A calorie is the amount of energy required to heat one litre of water to 1°C). Therefore, increasing the amount of oxygen consumed both during and after a workout, can increase the amount of net calories burned.

3. Circuit training and heavy resistance training with short rest intervals = a significant EPOC effect.

Strength training with compound, multi-joint weightlifting exercises or a weightlifting circuit that alternates between upper and lower-body movements places a greater demand on the involved muscles for ATP from the anaerobic pathways. Increased need for anaerobic ATP also creates a greater demand on the aerobic system to replenish that ATP during the rest intervals and the post-exercise recovery process. Heavy training loads or shorter recovery intervals increase the demand on the anaerobic energy pathways during exercise, which yields a greater EPOC effect during the post-exercise recovery period.

4. High-intensity interval training (HIIT) is the most effective way to stimulate the EPOC effect.

The body is most efficient at producing ATP through aerobic metabolism, however at higher intensities when energy is needed immediately, the anaerobic pathways can provide the necessary ATP much more quickly. This is why we can only sustain high-intensity activity for a brief period of time – we simply run out of energy. HIIT works because during high-intensity exercise, ATP is produced by the anaerobic pathways – once that ATP is exhausted, it is necessary to allow it to be replenished. The rest interval or active-recovery period during an anaerobic workout allows aerobic metabolism to produce and replace ATP in the involved muscles. The 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 through only the aerobic energy pathway.

5. EPOC is influenced by the intensity, NOT the duration of exercise.

Higher intensities require ATP from anaerobic pathways. If the ATP required to exercise at a particular intensity was not obtained aerobically, it must come from the anaerobic pathways. During EPOC, the body uses oxygen to restore muscle glycogen and rebuild muscle proteins damaged during exercise. Even after a HIIT workout is over, the body will continue to use the aerobic energy pathway to replace the ATP consumed during the workout, thus enhancing the EPOC effect.

6. Research has shown that resistance training can provide a greater EPOC effect than running at a steady speed.

One study found that when aerobic cycling, circuit weight training and heavy resistance exercise were compared, heavy resistance exercise produced the biggest EPOC.

7. The EPOC effect from a HIIT or high-intensity strength-training workout can add 6-15% of the total energy cost of the exercise session.

High-intensity workouts require more energy from the anaerobic pathways and can generate a greater EPOC effect, leading to extended post-exercise energy expenditure. Heavy weight training and HIIT workouts appear to be superior to steady-state running or lower-intensity circuit training in creating EPOC.

Watch Metafit’s Justin Corcoran (below) demonstrate the correct technique for the exercises in the May 2018 “10 Lashes” workout:

Increasing the intensity of your workouts will produce results.

It is important to remember that it is the intensity of your workout that produces the results. There is some debate about the significance of the EPOC effect for the average exercise participant because the high-intensity exercise required for EPOC can be extremely challenging. However, if you want results and are up for the challenge, increasing the intensity of your workouts by using heavier weights, shorter rest intervals or high-intensity cardio intervals may be worth the effort. While HIIT or heavy resistance training is effective and beneficial, remember to allow at least 48 hours of recovery time between high-intensity exercise sessions and try to limit yourself to no more than three strenuous workouts per week.

Thanks to the American Council on Exercise.

Metafit tips:

  • At the end of every Metafit session you should feel exhausted and be unable to hold a conversation for a minute or two.
  • If you are able to carry out a conversation during your workout you are not pushing yourself hard enough and you are unlikely to reach EPOC.
  • It’s important to get your technique right and it is better to use the regressive form of each exercise if you are struggling to maintain technique. Poor technique = less benefit and more likelihood of injury.
  • Think “slow and controlled” for your core exercises, particularly hot hands and hot knees.
  • That voice that says “I can’t do it” is the very same voice that says “I can do it!” Your mind will tell you “I can’t continue!” but if you push yourself a little further each time you will see that your body is perfectly capable of doing additional reps. Keep going no matter what – remember each interval is usually no more than 25 seconds.
  • If you are finding an exercise easy, then progress your technique by adding a jump or a tuck jump (for instance, adding a tuck jump after a burpee). Please ask me and I can show you progressions on all your exercises.
  • Metafit should never get easier – the fitter you become, the harder you can push yourself.