Anatomy of the deltoid muscle

The deltoid is the main muscle in the shoulder, and is anatomically divided into three groups of fibres or "heads": the anterior deltoid, the medial or lateral deltoid, and the posterior deltoid.

All three heads converge in the humerus, but they originate from three different points.

Anatomy of the deltoid muscle in the shoulder

anatomy of the deltoid muscle

Anterior deltoid

Originating from the clavicle, its main function is to raise the arm forward or advance it (bring the arm from outside to inside).

Lateral deltoid

Originating from the acromion on the scapula, its role is to move the arm outside or sideways.

Posterior deltoid

Originating from the spine of the scapula, its function is to move the arm back.


All the shoulder movements described are not carried out by the deltoid exclusively, but rather take place in synergy with other muscles. It is virtually impossible to completely isolate the deltoid with an exercise, because, depending on the movement, different muscles of the upper body come into play to complete the kinetic chain of the movement.

Let's see which exercises are best for training the deltoid.

1 - Reverse Pec

Reverse pec back shoulder deltoids workout exercise

The first exercise trains the posterior deltoid muscle, which is typically weaker than the other two.

Position yourself tight against the pillow and grab the grips with your palm facing down.

Stretch while opening your arms outward, about 1 second for the contraction phase. Hold the maximum contraction position for a little less than 1 second and slowly return to the starting position, a negative phase of about 4 seconds.

Exhale as you contract your muscles and exhale when you return to the starting position.

2 - Side lifts

Side lift shoulder deltoids workout exercise

Side lifts are probably the most famous and best known exercise for the shoulders, which isn't surprising given how important they are.

Grab the dumbbells with your palm facing your sides.

Contract your deltoids and raise your arms outwards until they are in a parallel position to the ground.

Exhale as you contract, and exhale as you come back to the starting position.

The forearm should be extended. A slight physiological flexion can help to properly engage the whole kinetic muscle chain, but don't make the angle too closed. The idea is to shorten the lever to facilitate the dumbbells being lifted, but the intensity of the exercise is also shifted to the anterior deltoid rather than focusing on the lateral deltoid.

Be careful when choosing a suitable weight for the exercise, which must be done in the correct way in order to achieve a result.

When you open out your arms, lift them outwards rather than keeping them close toward your chest, as this unbalances the load more towards the anterior deltoids.

3 - Slow forward stretches

Slow forward stretch shoulder deltoids workout exercise

The slow forward exercise is also known as the front military press.

It looks like a simple exercise, but in order to be carried out correctly the trajectory of the barbell movement needs to be controlled.

Unless you're a professional athlete and can properly control the contraction of the muscle groups in a way that directs the stress of the exercise to target the muscles that you want to train, it is important to follow the correct trajectory.

The barbell should be held at shoulder width, with your palms facing forward, and positioned at the base of the neck, under the throat.

Exhale, stretch your arms upward and push the barbell above your head.

While stretching, avoid following the perfect vertical trajectory. The perfectly vertical trajectory, which involves tilting the head back so that the barbell is not obstructed, facilitates the movement, allowing greater weights, but shifts part of the overload of the exercise from the deltoids to other muscles, such as the pectorals and triceps.

As such, to carry out the exercise correctly:

  • do not tilt your head back but look straight ahead
  • start the repetition by passing the barbell in front of your chin
  • continue vertically in front of your face
  • when you get above the forehead, gradually begins to bring the barbell slightly back
  • continues to lift, and come into the full extension position in order to have the barbell perfectly over the centre of your head
  • in the descent phase, follow the same path

4 - Front lifts

Front lift shoulder deltoids workout exercise

This exercise is performed on alternating arms to ensure the stability of the body, and thus focuses more on the muscle contraction of each shoulder, especially the anterior deltoid.

It is not a muscle isolation exercise, however. In fact, the movement also involves the pectoral, the trapezium, the biceps brachii and the coracobrachialis.

Holding the dumbbells with your palms facing toward the body, raise your right arm in front of you, spending 1 second on the contracting phase. Avoid jerking, which facilitates the lift but makes the exercise pointless.

Return your arm to the starting position, preventing back problems by not letting it drop down, but keep your position under control at all times.

Exhale in the descent phase, and then start again with the repetition for the left arm.

5 - Six ways

Six ways shoulders deltoid training exercise

Initial position for the repetition, phase 2, phase 3

Six ways shoulders deltoid training exercise

Step 4, step 5, and step 6 of the repetition. Then it's back to the starting position


The perfect exercise to complete the shoulder training is the six ways, an exercise where each repetition combines six different movements that must be performed in a precise and controlled manner.

Sitting down, grab two dumbbells with your arms at your sides and palms facing inward.

Keep your chest out and abs contracted in order to stabilise the torso and the whole body.

Here are the six movements of the six ways:

  1. raise your arms outward (side lift)
  2. stretch your arms out in front of the body
  3. raise your arms above your head
  4. bring your your arms back in front of your body
  5. open your arms outwardly again
  6. bring your arms back to the starting position

From here, start of a new repetition.

This is an exercise that should be carried out slowly with a side lift, as it is difficult to complete an entire series with a high load.


Now let's see how to combine these 5 exercises in a complete workout for the shoulders.

Training table for the deltoids

Here is a complete workout for the muscle mass of the shoulders, proposed by Gabriele Andriulli, Professional IFBB Wheelchair athlete on the Yamamoto Nutrition team.

Warming up

Two sets of the first exercise using a light weight with an isometric contraction at the peak of the exercise.

Recovery between sets

The recovery between sets lasts between 40 seconds and a minute. The weights must be appropriate to the execution technique, which must be controlled in any case.




Reverse pec


with 5-10 final partial slow reps

Side lifts


with negative 4 seconds and last set of 3x8 with decreasing weight

Slow forward stretches

1x10-8-6 / 8-6 / 8

with negative 4 seconds

Front lifts



Six ways