Hi,Caleb!
In case Cathe can't get to your question (she's busy, busy, busy editing and finishing up the STS DVD's!): the STS program is weights only, no cardio. There is an optional plyometric leg workout (for those who don't have the equipment to lift really heavy at home), but it isn't 'cardio,' just basic jump training. (I don't remember if the step is used for some of the moves, but if so, it's not choreographed cardio, just as a target for landing and taking off).
HTH!