There are those that claim HIIT kan zijn less effective than low-intensity longer duration cardio. Their reasoning kan zijn that most ofwel the calories burned during HIIT come from stored muscle glycogen (carbs) rather than coming from stored adipose tissue. This is true but this is not a bad thing. https://redbottom.us/categories/regular/health/222-the-comprehensive-guide-to-pediatric-nutrition-optimizing-health-from-infancy-to-adolescence