It seems everybody is jumping into the compund exercise bandwagon. I don't understand why people do not like isolation exercises. Sure, compund exercises are better at developing overall strength, but are isolation exercises really worthless? The answer is no. There seems to be a misunderstanding that isolation exercises work only one body part. This is not true. The concept of isolation comes from restricting the motion of other body parts so that the considered prime mover for the exercise gets more attention. But do the other muscles under the said restriction do not work? No they still work to stabilize your posture while doing the exercise. Take for example doing chest flyes on a pec-deck machine. The chest are the prime isolated as the prime movers while the other muscles of your body keep you from moving to achieve the manouver. The human body acts as a unit and rarely does a body part exhibit an action without the involvement of another. As to the benefits of isolation exercises, they are very good way to keep you from reaching a plateau or breaking from it. Using the same exercises every time will soon get you on plateau even if you increase the poundage. Seem to be stuck on your barbell squats? Go for to the leg press and hack squat (heck even those leg curl ad extension) machines for a few weeks and you'll find your squat improved. The body part is subjected to a new kind of stress (change in leverage) so it is kept confused. Meaning it will pile on whatever is necessary to adapt. I'm not trying to discount the benefits of multi-joint exercises. I believe that these exercises help you achieve the fastest possible development. To dismiss the isolation concept, however, would seriously hamper your strength training as far as breaking past plateaus.