Pectoralis Major is made up of two parts. The sternocostal head (lower chest) and the clavicular head (upper chest). The sternocostal head attaches on the sternum while the clavicular head attaches on the clavicle. Both insert on to the upper arm.
The sternocostal head is the largest part and is commonly disproportionately developed in trainees.
Pec major adducts the shoulder (imagine the lifting portion of a flye motion). The sternocostal head contributes to shoulder extension while the clavicular head assists in shoulder flexion. Pec major is strongest and, therefore, most stimulated when shoulders are internally rotated (think elbows flared in bench press).
Pec major is predominantly fast twitch (approx. 60%). With this in mind basing your training around heavier loads, lower reps and fast rep speeds is advised.
Loads between 70-90% 1RM have been found to be effective in compound pressing movements such as the bench press, DB bench press and Smith machine bench press. These movements all involve both shoulder horizontal adduction and elbow extension.
Isolation exercises for the chest (horizontal adduction) also stimulate high levels of muscle activation in the pecs. Machine flyes, pec decks and cable flyes/crossovers have all been shown to be effective at achieving this.
The pecs are best isolated by performing exercises which externally rotate the shoulder. A good example is a supinated grip flye. These types of flye require you to use less weight. As a result, the amount of mechanical tension you can create is somewhat limited. This is one of the reasons you very rarely see people doing them in the gym. Another reason is the fact that, although better isolated in external rotation, the pec major is biomechanically more efficient when internally rotated. This allows you to use more weight.
A combination of both externally and internally rotated shoulder exercises are, therefore, recommended to maximize chest hypertrophy.
As mentioned earlier externally rotated shoulders allow for better pec isolation but, limit the load that can be used. Having a pronated grip during flyes targets the pecs more effectively because they are stronger in this position.
Most people do flyes with DBs using a neutral grip. This is sub-optimal for two reasons:
- The range where the muscle is under tension is small as gravity is not directly acting upon the load for the final half of the movement.
- The arms are neither in their strongest position (internally rotated) or the best for isolating the pec (externally rotated)
A better option for flyes is to do them with a pronated grip on a cable machine. This provides a stronger contraction and constant tension on the muscle. You could add in an external rotation of the arm at the start of the movement to provide a greater stretch to the muscle and increase activation. Charles Poliquin is known to be a fan of this type of flye.
For pressing movements hand position and body angle can both effect the portion of the pec major worked. The more you flare your elbows out to the sides the more stimulus your chest will receive compared to the anterior delts. So to target the pecs benching in this fashion is a good choice. Doing so does, however, cause many people shoulder pain.
Staying injury free is the best way to give yourself the chance to keep making progress. With that in mind if you feel any discomfort from benching with flared elbows do the smart thing and modify your technique to stay healthy. In this situation I would suggest using a more tucked ‘powerlifting’ style bench when using a barbell. Focus on retracting your shoulders blades and pushing the chest up to meet the bar. Doing so exposes your chest to more of the stress of the movement. Another option to stay injury free is to do the bulk of your pressing movements with DBs.
I’m sure you’ve all heard that you should do incline for upper chest, and decline for lower chest. Well the gym bros are onto something. Studies show the sternocostal head is highly activated in flat or decline bench presses with a wide grip. Conversely, the clavicular head is more highly activated using inclines between 30-60 degrees and with a narrower grip.
Training chest twice per week will provide great results for most but, it can be trained up to 4 times per week.
Aim for 15-25 work sets per week
EMG data suggest that the best exercises to stimulate the upper chest (clavicular portion) are DB Incline Presses, Guillotine Presses, Mid Height Cable Flyes and Banded Push Ups.
For the Mid Pec it appears that Flat DB Presses, Floor Presses, Guillotine Presses and DB Flyes cause the most muscle activation when measured through EMG.
The lower pec seems to be particularly stimulated by weighted Dips, while flye variations and the Guillotine Press also have impressive EMG activation.
Now you are armed with everything you need to know to build an awesome chest. Still unsure how to combine this all into a coherent training plan? Then hit me up with an email at firstname.lastname@example.org or over on Facebook at https://www.facebook.com/Flatwhitesfreeweights/ and I will be happy to help.