Before we begin, you need to ask yourself an important question: Do you really want to build a big chest? It's only going to make your shirts feel tighter and your waist look smaller, and force you to think twice about how you walk through door frames. Then again, those are all pretty good reasons. And with only about a month of summer left, it's high time you had something that turns heads at the beach (aside from your back hair, that is). So as long as you're prepared to deal with the consequences, I'm prepared to offer you the ultimate chest workout: a four-week program to put you on your way to possessing massive, muscular pectorals.
My plan works the pecs according to their anatomical structure. You see, your pectorals are big, fan-shaped muscles that originate at the ribs and connect at the collarbone and sternum. Like all muscles, they're controlled by nerve impulses-some of which travel to the fibers at the pecs' collarbone attachment, while others operate the fibers that connect to the sternum. Because of the different innervations and the multiple directions the fibers are running in, you must work the chest from a variety of directions to make sure you've stimulated all its fibers to grow. To hit your uppermost pec fibers, you need to perform chest exercises at an incline. (This not only activates those collarbone attachment nerves fully, it loads the chest's upper fibers more directly.) In order to work the lower part of your chest-the muscle fibers that run along the bottom of your sternum-you need to work on a decline, positioning the load in a manner that forces those lower-chest fibers to work harder.
This is not to say that you can isolate different areas of your chest simply by changing the angle of the bench you're using-any pushing motion, or movement in which your arms are brought in front of your chest, will work the entire pectoral area-but you can be sure some positions work one section of your pectorals harder than others.
So, in essence, the bodybuilders at your gym are correct when they break up their chest training into upper- and middle/lower-pec exercises. But don't believe them if they also tell you that you can bring up your "inner" and "outer" chest with cable crossovers and wide-grip bench presses. There are no nerves that activate the inner- and outermost pec fibers exclusively (the same fibers run across from the ribs to the sternum), so don't waste your time with any so-called "shaping" exercises for your chest. The multiple angles you'll train your pecs at in this workout will be more than enough to bring rapid growth to every corner of your upper body.