The word deltoid comes from the Greek letter delta. The term is used as an adjective to describe something whose shape resembles a capital delta. The most common use, however, is linked specifically to a muscle.

The deltoid is a triangular muscle that is part of the anatomy of mammalian animals. In the case of the human being, the deltoid extends between the clavicle and the shoulder blade, covering the joint of this bone with the humerus.

Innervated by the axillary nerve and supplied by the posterior circumflex artery, the deltoid is divided into three parts: the posterior part, the middle part, and the anterior part. In muscle, on the other hand, the deep face, the superficial face, the apex, the anterior border, and the posterior border can be recognized.

The posterior fiber of the deltoid inserts into the spine of the scapula, becoming involved in the movement of the arm as it rises backwards. The anterior fiber, inserted into the clavicle, contributes to the forward elevation of the arm. As for the acromial fiber, its function is to allow separation of the shoulder.

Those who want to train the deltoid muscle must perform different activities to exercise the three types of fibers that compose it. Although the muscle can be strengthened to improve the stability of the joint and resist greater efforts, it is important to also exercise the rest of the muscles in the area to avoid imbalances. The shoulder is unstable and the strengthening of the deltoid over the other muscles can cause injuries.

Very often, people who are interested in improving their fitness do not pay attention to the shoulders, but instead focus mainly on developing the abs and arms. The problem is that strengthening the delts is essential to achieve the perfect finish, and for this you need to have a proper shoulder routine. As mentioned in a previous paragraph, this muscle is divided into three portions, also called heads, and the secret of a good workout is to work them all.

Before starting to learn and practice shoulder exercises, it is recommended to search for images of the deltoid in books or on the Internet to identify each of the three heads and locate them in our body. In this way, as we develop them with practice, we will be able to verify their progress by touching these areas with our hands.

Next we will see two of the most recommended exercises, which are based on isolating the deltoids, although it is inevitable to also use the triceps. The first is known as the Arnold dumbbell press, named after Arnold Schwarzenegger, its creator. It’s a variation of the traditional shoulder press, and offers a rotational movement throughout the range, forcing all three heads to work.

The Arnold press is made up of the following steps:

* sit on a bench with support for the back and leave the weights on both sides;

* Grasp the weights slowly and bring them up to your chin, keeping your palms facing your torso;

* raise them slowly, without moving the dumbbells away from the torso;

* rotate your hands as you arch overhead to lift the weights.

The second of the deltoid-defining exercises is called the behind-the-neck press, and bodybuilding veterans love it as it’s great for widening the shoulders. We must start by placing the bar at the ideal height for our body, and then:

* grab the bar from both sides to lift it using the strength of the legs;

* slowly spread your legs until they are in line with your shoulders;

* exhale and lift the barbell over your head until your arms are fully extended;

* hold the position for a maximum of two seconds, inhale and return to the initial position.