These are VERY high impact workouts. I think Interval Max (the original) may be a bit less jumpy, but maybe I just have that impression because each interval blast is just one move instead of a series of moves).
I haven't tried IMAX3 yet, but if/when I do (I got rid of the other IMAX workouts because of the impact), I intend to modify quite a few of the blast moves in different ways: slowing them down by doing 1 for every 2 moves Cathe does, changing some to "Low-Max-type low impact blasts, not jumping as high or as long, or taking some moves to my rebounder.
I'd like my 48-year-old knees to last me quite a while longer!