Originally Posted by Rickson
Circuit training was designed to combine aerobic and anaerobic exercise and it's not a bad thing if your goal is conditioning, but for muscle hypertrophy, you might want to break down your bodyparts because keeping the blood flow in one area of the body will get you more muscle breakdown than jumping from one bodypart to another. If you want to condition yourself then keep doing what you're doing, but if you want to improve your overall muscle development, break down your bodyparts to 2 a day such as chest and back one day, and legs and shoulders on another day.
Thanks for the answer Rickson. Right now, I think I'll stick with the circuit - I could use the conditioning for my tennis game and the aerobic element also seems to help me slim down a bit. Also, it lets me get my work-out in since I can usualy make it to the gym 2x or 3x a week.
But in the past, once I got bored of circuits and was able to get to the gym
4x a week, I usually broke things out into a push/pull split or an uppper and lower body split.