There (for example) is High intensity interval training.

What that is depends somewhat on who you ask but to give an example.

Take a normal exercise like cycling for 45 minutes.

If you do HIIT you cycle as fast as you can for 10-15 seconds (or until properly worn out) then rest long enough to be able to do it again. You only end up working out for less than one minute or just half a minute in total but you get similar if not better results than the 45 minutes workout.

So yes, running up the stairs as fast as you can until you feel like you are going to die would be high intensity. Take the elevator back down or you might die for real.