Hello @repholder,
Thanks for your reply. The type of training is indeed dependent on the goal that you set for yourself and to which sport your focus lies. Our body adapts differently to the way we exercise. A marathon runner's heart needs to function differently than short distance sprinters. I have taken two extreme examples so people can see the difference quickly. But nevertheless HIIT exercises can be a great tool for people who want to achieve good shape, build muscles, and get good health.