Many people associate interval training with blod, sweat and tears. All stuff you probably would like to avoid. We are here to tell you that out of these three, there is only sweat you will need to get in better shape, quick and easy.
The actual implementation of 4x4 intervals is quite a short process. In total, there are 16 minutes of higher intensity. How long the actual session lasts is up to you and what duration you want during the active breaks. We recommend that you have a minimum of 3 minutes of active break between each interval.
The purpose of the warm-up is to get you ready for the workout. You need to determine how long time you will need for your warm-up, but if you want to stick to the app's formula with 6 minutes of warm-up, we recommend using this time to build yourself up to the desired intensity. You should always experience the speed and incline as comfortable during the warm-up.
In the intervals, aim for an intensity that, after a few minutes makes you breathe so heavily that you are unable to speak in full sentences. This means that the first minute to one and a half minutes of an interval should be experienced as quite "easy". When, after about one minute into the interval, you are unable to speak in full sentences, do not push yourself any further. At the right intensity, you should be short of breath with not feeling any kind of discomfort. Using a heart rate monitor with the app will guide you to the right intensity.
A rule of thumb is that you should be able to continue for another minute at this intensity when the active break begins.
During the active breaks, reduce your speed so that you can breathe and speak normally again. Make sure that the intensity does not fall too low, as this will only make it harder for you to get your heart rate up again in the next interval. Get ready to repeat a new interval.
The last active break is the cooldown of the workout. Use this time to actually cool down and ask yourself: "Would I be able to complete another interval of 4 minutes now if I had to?". If the answer to this is "yes", you have completed the training correctly. If the answer is "no", you have trained too hard.