One thing I have learned is that shoulders can be one of the most amazing areas of the upper body anatomy, but at the same time the most difficult to target. Specifically in our posterior deltoid, this area requires a lot of different angles and ways to isolate moreso than the anterior and medial deltoid.
To help us better understand the shoulder and its functions, we need to grasp the concept of its anatomy.
The shoulder is a multi-axial (moves in all planes of direction) joint, similar to the hip joint . It has the smaller stabilizer muscles of the rotator cuff that support and help with abductuon, adduction, internal rotation and external rotation. Outside of this area, the shoulder has the larger muscles of the deltoid that are mainly focused on anterior, lateral, and posterior flexion as well as extension of the shoulder. All of these components assist the shoulder with the multi-directional motion it is capable of performing.
I try to really focus on the isolation of the posterior deltoid as shown in this video because this can be the most challenging part to work. Why is that? Many times we have a tendency to elevate the shoulder with assistance of the trapezius and rhomboid muscles. Also, because of the movement required to focus on posterior deltoids, this can easily add pressure on the AC joint if not controlled or using excessive weight.
I prefer utilizing an incline bench (45-60 degrees) for performing most of my posterior deltoid movements. This helps prevent the assistance of the other muscles mentioned prior, plus it prevents momentum from coming into play. One could easily spend most of the time using these three particular movements and only feel the work in the posterior deltoids. You can also add some variations with bands but only using a lighter resistance. Too much resistance will prevent full recruitment and add unneeded stress on the humeral joint.