Muscle Building's Greatest Hits  

The human body is an extremely efficient machine. It can adapt to a changing environment by heating and cooling itself, it can fend off illness with its powerful immune system, and it can metamorphose into a bigger or smaller form, depending on the demands placed on it. Pretty spectacular stuff! As a bodybuilder you’re trying to increase the stress on your muscles to force them to grow beyond their normal size. That can be a difficult job because the more you throw at your body, the more it adapts and tries to hold on to its normal size. Mother Nature doesn’t see a need for all that extra muscle, unless those muscles are absolutely necessary for survival—which means you have to trick Mother N. with constant changes in stress.
Ah, change. It’s what bodybuilding is all about: You’re trying to change your body, and in order to do that, you have to continually change your workouts.