I am wondering about the circuit workouts and how to do them in my schedule. I workout the upper body one day and the lower body the next day along with aerobics. I use heavy weights to get the most toning. About circuit workouts---can one use them in the rotation and just use lighter weights when it is the off day for that body section? For example---when it is my lower body heavy weight day and not my upper, can I do a circuit workout and use light weights for the upper and not disturb what I am doing with my upper body? I would also do a heavy weight workout along with the circuit for my lower body and then to heavy weights for the upper body the next day. I workout 5 to 6 days a week. Thank you!