Until today, Rhythmic Step has always made my knees sore and I couldn't quite figure out why. I do have some tracking issues but, Cathe's other tapes don't bother my knees. I've also read posts by others whose knees are bothered by Rhythmic Step. Anyway, today I figured out that my problem is with the drop sqats. Normally, when I do squats I have to turn my toes out slightly for my knees to be comfortable and I wasn't doing that with the drop sqats or the slow sqats. Making sure that I turned my toes out slightly made a HUGE difference. I also turn my toes out a little for the lateral over the tops and that takes stress off of my knees too. So, if you love Rhythmic Step, but your knees don't-give it a try! :7