100m sprinters do all out efforts for 9-10 seconds. So they don't have much use for endurance training. How do they manage to stay so lean? Do they the typical HIIT routines, e.g. sprint 30 seconds, walk 30 second, then repeat 6 times?
Perhaps they avoid this kind of training because the exhaustion will train their nervous systems to go slower?
Do they just do multiple sprints separated by long rests?
Maybe the key to their leaness is eating really cleanly?