The term ‘afterburn effect’ comes up repeatedly in connection with high intensity training. For some, it’s a miracle cure for burning calories; others claim it has hardly any effect. To this day, afterburn effect has not been fully researched because of the complex interaction between the underlying processes and systems.

Oxygen deficit and compensation

Among other things, our body needs oxygen to generate energy – the more work it must do or the more intense the stress on the body is, the more oxygen it needs. High intensity exercise such as WBC training raises your pulse, respiratory rate and body temperature and your entire metabolism to a very high level over a very short period. 

It takes a few minutes after beginning a vigorous workout that your body is able to use as much oxygen from the air as it needs. Due to this time delay, an oxygen deficit has occured. This deficit will be compensated after training. Then, even more oxygen is absorbed, more than is actually needed to recover the deficit. You could say that the oxygen debt is being repaid with interest. This effect is called excess post-exercise oxygen consumption (EPOC).

Even when we are all rested after a training and our breathing has seemingly normalized, cellular respiration continues at full speed. Much energy is being used to regulate the many different systems back to their normal levels. In addition, our muscles remain in a heightened state of tension and regenerative process, such as the replenishment of glycogen and oxygen reserves. During this time, the repair of the micro traumatisms and increased protein synthesis, the depletion and recovery of lactate, the strengthening of the heart and vessels, the distribution of corresponding hormones, and many more processes, are all initiated. Together these require a large amount energy from our body, so prompting the so-called ‘afterburn effect

How long does the afterburn effect last?

The intensity of the workout determines the duration of the subsequent afterburn effect. Although strictly speaking, an afterburn effect also occurs with low and medium intensity exercises, it is only really significant at a high intensity level. Researchers agree on one thing: the afterburn effect reaches its climax in the first hour immediately after a workout; then it decreases exponentially.

How is the afterburn effect detected and measured?

The content is measured via a breathing mask and a spirometry device, which the athlete wears during and after the workout. The result: with high intensity workouts, a high carbon dioxide content is shown not only during exertion, but also several hours later – a clear indication of increased cell and thus metabolic activity.

What exactly is the intensity of the afterburn effect?

Since performance determines the intensity, the relative value of the afterburn effect cannot be determined exactly. The highest possible afterburn effect, however, can only be achieved if the athlete really goes to the limits of their performance during the workout. Training conditions can also vary greatly from workout to workout: sleep, nutrition, stress, illnesses, hourly hormone composition and many more have a direct impact on performance, which can therefore vary from training to training.

Particularly for people with a low metabolism and the objective to burn fat, the afterburn effect triggered by high intensity workouts could be a deciding factor!

Afterburn effect and food intake after a workout – a contentious issue

The afterburn effect and its impact has not yet been fully researched. With regard to optimal nutrient utilization, faster regeneration time and psychological well-being, we generally advocate for food intake immediately after a workout. As always, we recommend fresh and high-quality products, and the focus should be on proteins.

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