Rear (Posterior) Deltoid Head

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The posterior deltoid head is one of three heads of the deltoid structure, which is located at the rear of the shoulder. The deltoid was more commonly known as deltoideus, because of the shape of the Greek letter Delta, a triangle.

The rear deltoid head is often the most neglected head of the deltoids. This could likely be because the rear deltoid does not experience much stress from the commonly used overhead pressing movements, which stimulates the front and side deltoid heads greatly.

Just as the front deltoid head is worked greatly by pressing actions- the rear head is often stimulated greatly during rowing exercises, as it works to bring the arm backwards. This shows the complexity of the shoulder joint, as it moves through many directions and planes. Some people may choose not to directly target the rear head, and rely on rowing exercises to stimulate the rear head.

Focusing isolation work on the rear 'delt' also makes sense as it is not targeted greatly by over-heading pressing exercises. These exercises can be viewed in the exercise section to the right.

The deltoid is like most other muscles. For hypertrophy 6-12 reps will likely yield the best results, providing optimal time under tension for sarcoplasmic hypertrophy.
If however strength and power is the primary goal then the rear deltoids head will likely be best stimulated indirectly by rowing movements, where 1-5 reps can be incorporated successfully. Lower reps don’t always suit isolation movements, as form may suffer, and increase chances of injury, especially to the smaller rotator cuff muscles (Subscapularis, Supraspinatus, Infraspinatus, and Teres minor).