The Adductor machine is probably the most useful machine there is since it is very difficult to hit those muscles otherwise. When you squat maximum weights you will see that your knees start moving inwards if you have weak Adductors. This is very bad for your knees and your squat poundages. The Adductor (your legs move inwards against the resistance) helps to prevent this. 2 or 3 sets once a week is all you need. Reps will vary depending upon the machine, but you will definitely need to get up to the whole rack for at least 10 reps to ensure your knees don't move in when using over 405lbs in the squat. The Abductor (Legs moving outwards - think Lindberg's baby was Abducted, taken out of the house) is fairly useless.
