We know now that many elements in the universe are interconnected.  The human race is well aware of this.  At the risk of sounding metaphysical, most objects in our visible world exist in relation to one another.  The human body is exactly the same.

Our bodies are not series of separate parts which exist entirely separate of one another.  The human body is an integrated organism.  Each part is related and has an effect on the greater whole. Intense exercise  stimulates muscle growth. Although it may seem that we are working individual body parts, we are actually effecting the entire body. This is simply a fact. Also, the larger the specific body part trained, the greater the overall effect on the body.

Barbell squats not only produce strength and  muscle increases in the legs they also produce incredible growth throughout the entire body.  The reason for this is still pretty much unknown.  What we do know for sure, is this: Performing the barbell squat, not only produces direct muscle mass  increases in the legs, but it
also produces indirect increases in the arms, shoulders, chest, neck and back. In short, All over the entire  body. This one exercise (the squat) can produce incredible increases in overall muscle gains.

Even though muscle mass increases can be stimulated throughout the entire body by exercising a single large body part, even more muscle growth will be achieved from a balanced program.  That’s how you build muscle fast, by focusing on these muscle growth exercises.

In other words, if you just concentrate on one body part (like the legs), disproportionate development can quickly occur.  So the prevent this from happening,  all the major body parts should also be worked directly.  I want you the understand this point loud and clear. There is no such thing as isolated or ‘split-body’ training.  Every time you exercise a specific part of the body, you are indirectly affecting the body as a whole.

Unfortunately, many trying to gain weight ignore the major areas of the lower body.  They choose to concentrate solely on the upper body.  Much bigger muscle gains would be made, and much more rapidly, if they realized that the body as an integrated whole.