I am wondering if it is possible to change the shape of any particular muscle. Someone wrote this about it on a site online and I wonder what you all think:
"Actually, your “chest” muscle is comprised of two main muscles: the pectoralis major and pectoralis minor.
Your pectoralis major is the “bulk” of the muscle, and spreads from your sternum to your shoulder. This is the muscle that you see.
Your pectoralis minor is actually beneath the major muscle, and serves mainly as a “tie in” to the shoulder joint.
It is a myth that you can work “upper” or “lower” pec muscles. This has been confirmed time and time again - even through electrodes. When you shift the workload, i.e. by performing an incline or a decline, you simly change the way various muscles interact. For example, an incline bench press incorporates your deltoids (shoulder muscles) to a greater extent, while a decline bench press requires more involvement from your lats to maintain the angle of your arm.
No matter what “angle” you hit the pecs from, the entire muscle can either contract, or not contract. The muscle is comprised of motor units, and a single motor unit is a group of neurons/nerves in the muscle. Motor units are NOT localized - one motor unit is typically spread evenly throughout the muscle. So whether you perform an incline or decline, the muscle is still only going to contract or not, it doesn’t contract in a specific “area”.
Flyes perform the main function of your chest, namely moving the upper arm closer to your mid section. A bench press, on the other hand, mimics this movement but also changes your elbow angle, therefore involving the triceps and shoulder to a larger extent than fyes.
In short, there is no such thing as “inner pecs” or “lower pecs”.
This doesn’t mean that you shouldn’t use a variety of angles - by changing from incline to decline, etc, you work different groups of muscles and force your central nervous system to continuously change its mode of adapation, and this is one of the stimuli for hypertrophy (muscle growth).
However, you are stuck with the current shape of your pectoralis muscle. You can make it larger or smaller, but short of tearing or otherwise physically manipulating it, you cannot change it’s shape.
Having said that, many people who feel their “inner” or “lower” pectoralis muscles aren’t developed, simply have too high body fat. , revealing the muscle definition. "
What do you think???