The machine shoulder press is one of many shoulder exercises and machines that work the shoulder muscles. This exercise, when done properly, targets the anterior deltoid muscle in the shoulder, and it works several other muscles which are used as synergists, stabilizers, and dynamic stabilizers. Sit with your back pressed into the backrest with the handles set at shoulder height or slightly higher. Exhale and press the handles up until your arms are straight but not locked. Pause then slowly return to the starting position. Do two sets of 12 to 15 reps.
Anterior Deltoid
Also called the front deltoid or the front shoulder, the anterior is located at the front of the shoulder. It runs from the clavicle to the deltoid tuberosity on the humerous bone in the upper arm. It is responsible for abduction, lateral arm movement away from the body; flexion, lifting the upper arm up towards the front of the body; transverse flexion, moving the upper arm in and across the chest with elbows out; and internal rotation of the shoulder, turning the upper arm in.
Lateral Deltoid
The lateral deltoid, worked as a synergist muscle in this exercise, is also known as the side deltoid, or the side of the shoulder. It is attached at the scapula and inserts at the deltoid tuberosity in the humerus bone. The lateral delts aid in shoulder abduction, shoulder flexion, and shoulder transverse abduction. As a synergist muscle in this exercise, the lateral deltoid works to assist the anterior deltoid throughout the movement.
Trapezius
The trapezius muscles, so-called because of their trapezoid shape, runs longitudinally from the occipital bone to the bottom thoracic vertebrae and laterally out to the scapula on each side of the body. The trapezius functions to support the arm and move the scapula. With the machine shoulder press, the lower and middle trapezius muscles are used as synergists, while the upper trapezius are used as stabilizer muscles.
Triceps
The triceps, or triceps brachii, is the muscle located on the back of the upper arm. It is divided into three heads, each of which is responsible for straightening the elbow joint as well as extending and adducting the shoulder. With the machine shoulder press, the triceps is used as a synergist muscle, and is worked as the elbow is extended.
References
- ACE GetFit; Seated Machine Shoulder Press
- "Bodybuilding Anatomy"; Nicholas Evans; October 2006
- "Strength Training Anatomy"; Frederic Delavier; September 2001
- Full Fitness; Machine Shoulder Press
- ExRx.net; Shoulder Articulations
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