What Muscles Do Shoulder Shrugs Work?

Jun 15, 2011 | By Michele Turcotte, MS, RD

You can perform shoulder shrugs, a popular weight training exercise, with dumbbells, a barbell or using a plate-loaded lever. While most individuals think---due to the name of the exercise---that it works the heads of the shoulder, the target muscles for this exercise are actually located in the upper back and neck.

Upper Trapezius

According to the Exercise Rx website, the major movers, or target muscles engaged during shoulder shrugs are the upper fibers of the trapezius. These muscle fibers are also known as the upper shoulders or upper "traps" and run from the posterior, inferior side of the skull, or the lower back of the skull, to the posterior clavicle, or the back of the shoulder. In other words, the upper trapezius is the muscle located between the neck and the shoulder, from the posterior.

Middle Trapezius

The middle trapezius muscle is a synergist, or helper muscle, engaged during shoulder shrugs. Also known as the upper back or "traps," this triangle shaped muscle runs from the spine---specifically the cervical vertebrae (C7) to the scapula, or shoulder blade. In addition to elevation, this muscle is involved in other movements, such as adduction, which is a backward movement toward the midline of the body; and upward rotation, or moving the lower part of the scapula laterally and upward.

Levator Scapulae

Another synergist, or helper muscle, engaged during a shoulder shrug is the levator scapulae. Other names for this muscle are the upper shoulder or rear neck, though anatomically, this is more of a neck muscle than a shoulder muscle. The levator scapulae muscle runs from the cervical vertebrae (upper C3 or C4) to the top of the shoulder blade, also known as the transverse process. As the name indicates, the main movement of this muscle is elevation.