Dumbbell One-Arm Shoulder Press

The shoulder press is an exercise that works all three heads of the deltoid (but not to the same extent). This is the deltoid muscle responsible for lifting the upper arm. In the one-arm dumbbell shoulder press, this is performed with one arm at a time.

The pectoralis major assists in lifting the arm. Especially the fibers that run from the clavicle to the upper arm, also known as the upper chest.

In addition to the deltoid itself, various muscles around the shoulder joint are recruited to stabilize it. Smaller stabilizing muscles such as the four rotator cuff muscles, as well as the larger trapezius and deeper muscles that pull the shoulder joint backward and upward.

In the arms, the triceps play an active role by extending the arms, while the biceps have a stabilizing role in keeping the forearms in the correct position. The muscles in the forearms themselves then stabilize the wrist joint to control the dumbbells.

Core muscles such as the abdominal muscles and muscles along the spine keep the torso upright. Depending on the execution (standing, seated with or without back support), their involvement may be greater or smaller.

One-Arm Dumbbell Shoulder Press Execution

Focus on the elbow and push it straight upward until it passes shoulder height. At the end of the movement, the arm is almost fully extended.

Lower your arm in a controlled manner until the dumbbell is at ear height.

Repeat with the other arm.

One-Arm Dumbbell Shoulder Press

Muscles involved:

Shoulder joint:

Deltoid

Rotator cuff (subscapularis, supraspinatus, infraspinatus and the

teres minor)

Trapezius

Rhomboid

Levator scapulae

Arms

Triceps

Biceps

Forearm muscles

Abdomen:

Rectus abdominis (straight abdominal muscle)

External oblique (external oblique abdominal muscle)

Internal oblique (internal oblique abdominal muscle)

Transversus abdominis (transverse abdominal muscle, 'corset muscle')

Lower back and spine:

Erector spinae

Lumbar multifidus

Quadratus lumborum

One-Arm Dumbbell Shoulder Press Preparation

Sit on a bench with the backrest (almost) fully upright and the dumbbells on your knees.
Raise your knees one at a time and bring the dumbbells into their starting position: The hands are approximately at ear height. The elbows are beside the torso. The palms are turned forward.
If necessary, push your buttocks back against the backrest. They may tend to slide forward when bringing the dumbbells up. If your waist has moved too far forward, you are leaning too far back and the chest muscles take over a larger part of the load from the shoulders.

One-Arm Dumbbell Shoulder Press Technique

Performing the exercise with one arm at a time means, among other things, that the muscles in the core and around the shoulders have to work hard to stabilize everything. This applies especially when performing the exercise with one dumbbell in your hands and switching arms per set (instead of per repetition). The lack of a counterweight means that you throw yourself off balance by moving one arm. Your core muscles will have to work harder to keep your torso stable. To the extent that they do not fully succeed, stabilizing muscles around the shoulder joint will have to work harder to compensate.

This is therefore also referred to as 'functional' because the coordination between the various muscles involved is given greater priority. Of course, this can come at the expense of developing the maximum strength of specific muscles such as the deltoid.

What is 'functional' also depends on which function you want to strengthen. In the variation in which you hold two dumbbells and perform the exercise alternately, the imbalance is smaller. The dumbbell that is held stationary then acts as a counterweight. This will therefore result in a smaller difference compared with performing the exercise with both arms at the same time.

The Three Heads of the Deltoid

The deltoid muscle pulls on the upper arms from three directions. During the shoulder press, all three of these "heads" of the deltoid are engaged. However, it is primarily the front head (pars clavicularis) that does most of the work, followed by the lateral head (pars acromialis). The rear head (pars spinalis) is engaged considerably less.

The shoulder press can be performed in various ways that can shift the load per head, but not by much. In most cases, the front of the shoulder produces three times as much effort as the side, which in turn produces on average three times as much effort as the rear.

Seated or Standing

Research has shown that when the shoulder press is performed standing, (all three heads of) the shoulders produce greater effort. The researchers point to the additional need for stabilization when the exercise is performed standing. This would mean that the standing execution is 'more effective' at engaging the shoulder muscles.

Another possibility, however, is that people often cheat during the seated execution. Performing the exercise standing forces you to stand upright so that you do not fall backward. This limits the possible contribution of the chest muscles. On a bench with a backrest, you often see that the backrest is already set too far back. The person then slides the buttocks somewhat forward, leaning even farther backward. The shoulders then need to produce less effort because the chest, especially the upper chest, can make a greater contribution.

At a glance