[insickness]

Ok, I missed where you were referring specifically to endurance athletes. You may be correct that endurance athletes do most of their training at lower intensities, although they almost all incorporate some type of higher intensity interval training.

The reason I separate elite athletes from others is that they are genetically different than the average person. To be an elite athlete in a super competitive sport, you are not representative of the normal population. You can likely train harder and longer and most likely have some type of other genetic advantage. It's far better to focus on studies that look at normal people rather than elite athletes.

Anyway, to go back to your original question, asking how HIIT is more effective, you are right that it is not necessarily effective at every endeavor. But literature shows that for the average person, doing 10 minutes of HIIT can be as effective in losing weight, gaining muscle, cardiovascular fitness, etc. as doing something like 30 minutes of low-intensity exercise.