In the beginning, it’s important to mention that high intensity interval training is not only an efficient way to burn fat and lose weight, for it has other benefits also, including raising VO2 level (the amount of oxygen the body can use which can be considered as a heart fitness index), lowering the lactate levels in muscles which helps you work out harder and longer and increasing enzymes activity to reduce the feeling of fatigue.
You can start with any workout program, but as you get used to that program you can adjust it to focus on the things you want to improve.
It all relays on the body’s energy courses, as there are three of them: the first one is ATP-PC which provides energy for high-power short-period exercises like sprints and quick lifting, the second course is called the glycolactic course which is specialized in medium-range activities, while as for the third course; it is called the oxidation course which is specialized in the remaining activities.
The first and the second course are anaerobic ones for they don’t use oxygen whereas the third course is considered aerobic because it uses oxygen, and HIIT workouts utilize both anaerobic and aerobic systems of the body, while as for utilizing the different energy courses it depends on the work-to-rest ratio you are applying.
In other words, we can say that 30 seconds of rest is not enough to improve energy and activity, and it’s also not necessary for you to be “dripping wet with sweat” for the exercise to be good, it all depends on what your aim is.