2. The Chest
The main muscle group of the chest is the pectorals. A well-developed chest is very important because it will add major size to your inner upper body. In addition, the chest is a very visible part of the upper body.
An exercise that will help to develop the pectorals is the bench press; the bench press works the entire pectorals. Another exercise that will help develop the inner pectorals is the narrow grip bench press.