I'm new to Cathe and need some advice. First of all I'm 52 and just trying to get back into shape after a 2 year slug cycle. I've used "Firm" tapes since about 1987 but now I only use them for cardio and I alternate the Pure Strength series afterward. I'm trying to burn fat with the cardio and build muscle with the Pure Strength. Should I be doing Slow and Heavy too? What's the difference between Pure Strength and Slow and Heavy? The descriptions sound very similar. I have bad knees and am looking at Ellipticals to replace some of the cardio workouts. I think it will reduce some of the stress on my aging joints. I'm hanging in there by using Ace wraps on both knees while I workout. Am I on the right track?