Built By Science: Shoulders

Boulder shoulders look great on any physique, but building them takes know-how. Here's the science you need to build a bigger, shapelier, healthier pair of shoulders!

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Men and women alike want to build an aesthetic set of shoulders. At the end of the day, if you want to build round delts, you need to keep your shoulders healthy and injury-free. Because the shoulder is crucial to so many movements, a shoulder injury is one of the worst you can encounter.

Knowing the anatomy of your muscles and bones, as well as the various functions of your shoulders, can help you train and grow your shoulders more effectively. It can also help you keep them healthy and mobile. I'm going to help you build a better, stronger, healthier set of shoulders.

Built By Science Shoulders
Watch the video: 16:07

Muscular Anatomy

Your shoulders are a complex, synergistic bunch of muscles that are responsible for a huge amount of movement. Here are the muscles you should be concerned with.


One of the best ways to think about your shoulder muscles is to pretend you're peeling layers off an onion. The first layer of muscle around your shoulder joint is called the deltoid. The deltoid has three particular heads.

Anterior Head

The anterior head is the piece of your deltoid on the front of your shoulder. It starts on the front of the clavicle, runs down and across, and attaches to your humerus.

Middle Head

This head lies next to the anterior head and is more central. It begins at the top of your scapula, or the acromion process, and attaches to outer portion of the humerus.

Posterior Head

The posterior head starts on the back of the scapula on what's called the scapular spine. It attaches on the humerus.

Rotator Cuff

If you peeled away the deltoids, underneath them you would find a deep layer called the rotator cuff. We've all heard the term before, but not everybody is familiar with what those muscles actually are.

Your rotator cuff consists of four muscles. The main function of these muscles is to stabilize your shoulder joint.


The infraspinatus is the big muscle that spans the outside portion of your scapula.

Teres minor

Under the infraspinatus is a smaller muscle called the teres minor.


This muscle runs from the scapula and attaches to the inside of the humerus.


The subscapularis muscle sits on the front of the shoulder blade.


Skeletal Anatomy

Bones and joints play a critical role in how your shoulders move. A solid grasp on how they work together will help you care for your shoulders better and train them more effectively.

Thoracic spine

The thoracic spine refers to the topmost 12 vertebrae. It starts at the base of the neck and ends at the top of the lower back. These vertebrae attach to ribs.


The scapula rests on top of the thoracic spine. For your scapula to move effectively during exercise, your thoracic spine needs to be set strong and tight.


The humerus is the long upper-arm bone. Most of the shoulder muscles insert into it.

Glenohumeral joint

You can't move your shoulders without the shoulder joint. Your scapula and humerus work together to create the movement of your shoulder and arms. Because the glenohumeral joint is a ball-and-socket joint, your arm can flex, extend, abduct, adduct, and externally and internally rotate. Shoulder mobility is critical.

Muscle Function

It's great to know anatomy, but that knowledge doesn't do us any good if it's not applicable. Here's how those muscles, bones, and joints you just learned about move in the gym.

Here's how those muscles, bones, and joints you just learned about move in the gym.


All three heads of your delts work together most of the time. For example, any time you take your arm overhead—like you would for an overhead press—all three of your deltoid heads will move synergistically. We can, however, perform movements to further isolate each head of the deltoids.

Anterior delt

One of the roles of the anterior delt is creating shoulder flexion. Shoulder flexion is raising your arm in front of your body … picture doing a front raise.

Middle delt

Your middle or lateral delts create shoulder flexion, but they also help create shoulder abduction. Shoulder abduction occurs when you bring your arms away laterally from the midline of your body.

Posterior delt

Your posterior delts are responsible for shoulder extension. Shoulder extension occurs when you bring your humerus back behind your body.

Your posterior delts are responsible for shoulder extension.

Rotator Cuff

The rotator cuff primarily creates stability. In other words, those muscles are always working to keep your humerus in the shoulder joint. The rotator cuff is also responsible for the internal and external rotation of your humerus.

If your shoulder and rotator cuff do what they're supposed to, you don't need a lot of isolated training to get the results you're looking for.

Internal rotation

Your subscapularis starts on inside of shoulder blade and turns your shoulder inward.

External rotation

On the backside of your shoulder blade lie your infraspinatus and your teres minor. These muscles externally rotate your humerus.

Shoulder abduction

The supraspinatus is there to lift your arm away from your side. If you read the research, you'll learn that the supraspinatus is responsible for the first 30 degrees of movement away from the body's midline.

Key Exercises

Apply what you've learned! Here are some great shoulders exercises that will help you develop those boulder shoulders and keep all the bones and joints healthy and mobile. Don't forget to train heavy and hard. Your muscles won't grow unless you stress them!

Keep in mind that you don't need to do a lot of isolation exercise for your shoulders. Your shoulders get a workout doing big, compound movements like the overhead and bench press.

EXERCISE 1 Overhead Press

This is a great movement because you're literally using all three heads of your deltoid muscle to create the movement.

The most important aspect of this lift is the setup. Keep your hips shoulder-width apart and your abs and your butt tight. A solid foundation will help you move more weight and keep your lower back healthy.

Overhead Press
Overhead Press

Bring the weight to your shoulders and then press it straight over your head. Use a nice, controlled motion. Some people don't move too well when the weight is overhead, so make sure your overhead range of motion is solid before you go full steam and pound heavy weight.

EXERCISE 2 Bent-over lateral raise

I like this exercise because it isolates the posterior delt on the back of the shoulder. Keep your knees soft and your hips back like you would for a Romanian deadlift. From this position, lift your arms up and out to the side. That's where you'll hit that posterior delt.

Bent-over lateral raise
Bent-over lateral raise

Too often people do this movement with excess momentum. Slow down. Use your muscles to move the weight. If you can't, it's a sure sign that you need to reduce the weight.

Better Shoulders, Built By Science

It's great to have aesthetic shoulders, but if you injure these guys, you're in big trouble. You can't train your chest, back, or arms—heck, even leg training can be a chore if your shoulders are hurt. It's important to train your shoulders for strength, physique, and health.

Take the time to warm up before you go through the workouts. If your shoulder muscles are weak, go lighter and do the exercises correctly. You'll get more out of the exercise that way.

Follow the Built By Science Program

We only highlighted two exercises in this video, so make sure you check out the full six-week Built by Science program! Watch all the overview videos before attacking the gym. Remember, you need to combine mind and muscle to build your best possible body.

Support your results with this muscle-building supplement combo! Go Now!

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