Know Your Muscle: Pectorals

Muscle Fibres

The muscle fibers of the Pectoralis Major originate in three different places:

  • the collarbone

  • the breastbone

  • and, the cartilage of several ribs near the breastbone

The fibers all attach to the humerus, but with a twist: the fibers that start at the bottom of the chest attach at a higher point on the humerus then the fibers that start on the top.

If you are, or have been a regular gym goer, the chances are that you have heard the talk surrounding the fact that working the pecs at different angles will work different areas of the muscle. Whilst many bodybuilders have a tendency to view at their chest muscles as having three distinct portions: upper, middle, and lower – that need to be worked separately for maximum development, this is not necessarily true. They’re not entirely wrong however, changing the angle does target different areas of the muscle more than others, but this isolationist style of training isn’t as significant as you might think. The twisting of the muscle fiber assures that most chest exercises work the majority of the pectoral muscle.

It is true that doing a chest press on an incline bench works the upper fibers slightly more than it does the lowers fibers and vica versa, doing a chest press on a decline bench will hit the lower fibers slightly more than the upper fibers, however, the majority of the your pectoral muscle fibers work in unison whenever the muscle is being worked. This means that you won’t be missing out on any significant muscle development by missing a few incline or decline sessions – concentrate on mastering the flat bench first (especially in your beginning years). This does not mean that you should ignore the various angles and exercises designed for targeted the chest – if for no other reason alone, performing the same exercise over and over with heavy weight takes its toll on your shoulders.

The primary function of the pectorals is to pull your upper arm across the front of your torso – this is why it is important to concentrate not just on pressing upwards during a chest press exercise, but also slightly inwards. For obvious reasons this subtle movement is easier to accomplish using dumbbells rather than a barbell.

Your pectorals also play a small part in pulling your arms down to your side – such as in a pull-up or lat pull-down. If your arms are already by your side and push down further, such as in a tricep dip, your lower pecs handle a substantial part of the load.

*The views and/or opinions expressed in the blogs are not necessarily those of Training Nation, but of the author

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