I used to use 2 sets of risers, but over the years I've taken out a set, and then another -- thanks to my knees -- until I came back to where I started when I was a beginner, just using the step.
Sometimes when doing the Imax workouts, I take the step out altogether. The impact alone drives my heart rate up like crazy. I also make sure my arms are moving. Cathe said in C&W that arms contribute 12% to a cardio workout.
After taking up kickboxing last year -- and after finally getting a workout like Low Max -- I realized I don't need so much impact, or a step, to get the most out of a workout.
Pinky