I am doing some programs but I am not certain which to follow. From one side I have Hiit, it's 25 minutes non stop (5 seconds between exercies) and I have really to try hard to end it. From the other side I have other 15 minutes intense" Trainings (for example the so called V taper). These are hard and intense but I don't feel completely exhausted as with HIIT. Do they work the same?