After warming up, circuit training such as Nautilus should always begin with the largest muscles in the body, the lower body muscles. The largest muscles must be worked first while your system is still capable of high work output. You start at 8-10 repetitions for each exercise so you do not run out of oxygen for the muscles being worked. There are no multiset exercises. When you are done with one machine go on to the next one.
Lower body exercises start with the leg extension, which works the quadriceps.
Then go to the leg curl machine, which works the hamstrings. Try to do nearly the same weight on both machines. This equalizes the muscles around the knee, improving the knee s structural integrity. Next go to the squat machine, which exercises the largest muscles of the lower body, the gluteus maximus, the quadriceps, hamstrings and the gastrocnemius. This is the single most important exercise.