Stand with a straight back, with legs slightly apart, arms hanging next to the body, holding a barbell in each hand:
- Raise the arms to horizontal with the elbows slightly bent.
- Return to the initial position.
This exercise mainly uses the middle deltoid.
The three divisions of the deltoids create a multipennate muscle whose different fiber directions converge on the humerus. Their function is to support relatively heavy weight and to move the arm through its full range of motion with precision.
Therefore, it is important to adapt training to the specifics of this muscle by varying the initial position of the movement (hands behind, to the side, or in front). This thoroughly works all the fibers of the middle deltoid. Because everyone’s physical structure is different (length of the clavicle, shape of the acromion, and height of the insertion at the humerus), you must find the angle of the initial position that is best for you. Lateral raises contract the supraspinatus, although you can’t see this because it is located deep in the supraspinatus fossa of the scapula (shoulder blade), where it attaches to the lesser tubercle of the humerus.
Raising the arm above horizontal contracts the upper part of the trapezius; however, many bodybuilders don’t work above horizontal so that they isolate the the lateral deltoid. This exercise should not be performed with heavy weights, but instead in sets of 10 to 25 reps, while varying the working angle without much recuperation time until you feel a burn. To increase the intensity, maintain an isometric contraction for a few seconds with the arm at horizontal between each repetition.