Your chest muscles are important for many things (other than filling out a t-shirt). They are responsible for flexing your upper arm when you swim, moving your arm inwards when you are riding a bike, rotating your arm bone toward your body while you walk or run, and also simply breathing deeply.
Before I dig into the details of how to get a strong and defined chest, I want to address a common fear that exercising like this will make women look like men and men look like balloon animals. To allay this fear, I am going to turn to biology.
All of us have a gene called GDF-8, and that gene is in charge of a substance called myostatin. Myostatin is in charge of controlling the amount of muscle we have on our body and how big our muscles develop naturally. The base levels of myostatin and muscle in the majority of us make it impossible for us to naturally build bulky muscles no matter how heavy a weight we lift. The majority of us simply do not have the genes to build bulky muscles via any form of exercise.
Sure there are a few people out there who can become bulky because they have the “bulky genes.” But they are few and far between and no matter how much most of us engage in resistance training, we will never cross that threshold that gives “bulking up” a bad name.
OK, with that out of the way, let’s talk about the chest muscles.
What Are Chest Muscles?
The main area of our chest is made up of two muscles we refer to as the pecs. These muscles work together to do the activities I described earlier. The muscles are:
- Pectoralis major
- Pectoralis minor
The pectoralis minor is located directly underneath the pectoralis major. Both of these chest muscles start at the clavicle (collarbone) and insert at the sternum (breastbone) and the humerus (armpit). The pectorals are mostly used to control arm movement. Contracting the pectoralis major results in pulling on the humerus to create lateral, vertical, and rotational motion of the arm. The pecs also play a role in breathing, specifically inhalation, by pulling the ribcage open to make room for the lungs to expand.
Even though the pec is divided into two parts, there are actually six separate sets of muscle fibers within the pectoralis muscle. This is important because these sets of fibers allow portions of the muscle to be moved independently by the nervous system.
Why Would You Want a Stronger Chest?
Getting a stronger and more defined chest goes beyond simply looking good at the swimming pool or in a tight shirt. Every day we use the pectoral muscles to do things like pushing a heavy door open, heaving a heavy load of laundry over your head, washing your hair, or simply getting up off the ground or the bed.
Even though they're not exerting the primary force, your pecs are also active when you pick up a bag off the floor, throw a ball, or push a grocery cart or stroller.
Because of those actions (and more), getting a stronger chest is advantageous for both aesthetics and performance. It doesn’t matter whether you are a powerlifter, weightlifter, endurance athlete, mom, or fitness blogger.
Chest Building Pointers
Though the chest is made up of one single mass of muscle that is broken into major and minor, we are best off training it like it is actually three parts—the upper, middle, and lower portions of the chest. The reason for this is that each region is stimulated best by changing the angle from which you exercise the muscle.
- Upper Chest: To best stimulate the upper chest, perform the exercises on a 30-45 degree incline bench. Examples of this are incline bench press or incline flyes. Both of those exercises are great for developing the upper chest.
- Middle Chest: To really target the middle chest, use a flat bench. Examples of this are flat bench press or flat flyes.
- Lower Chest: The lower chest is best exercised by working out on a 30-45 degree decline bench. And yes, you guessed it, decline bench press or decline flyes are great ways to target the lower chest.
Moving beyond the angle of your body, the upper chest will be targeted by doing movements that involve shoulder flexion. The middle chest will be targeted by doing horizontal adduction movements—especially ones that don’t involve shoulder flexion or extension. The lower chest will be best targeted with movements that involve shoulder extension.