Impingement of the rotator cuff tendons inside the shoulder joint is a problem experienced by some athletes whose sports involve overhead activities such as throwing, serving in tennis, and certain swimming strokes.  It is an even larger problem for a sizable segment of the general population as a result of the need to reach overhead during activities of daily living.

In the research and surgical literature, impingement is often divided into 2 categories: internal and external.

This distinction is critical from an anatomical perspective, but less important from a functional “probable suspects” point-of-view.  The anatomical source of the person’s symptoms must be addressed in any surgical procedure.  However, the dysfunction in the “Chain Reaction” could be the same for either type of impingement.  The causes / solutions must be identified for both pre- and post-operative training.

The Applied Functional Science (AFS) Principles of 3D and Chain Reaction influence all of our Strategies.  With cases of shoulder impingement, the Principle of LOAD & EXPLODE takes on additional importance.  Almost always the impingement occurs during the EXPLODE: the task our clients want to accomplish.  However, the pain during the EXPLODE is often rooted biomechanically in a failure to LOAD sufficiently.

For this blog, the insufficient LOAD will focus on frontal plane “suspects”.  Pain with abduction in the frontal plane is often caused by failure of the acromion of the scapula to get out of the way as the humerus abducts as part of reaching overhead.  If the scapula doesn’t adduct during the LOAD, then the EXPLODE will be less that optimal.  Tracing the Chain Reaction of the LOAD all the way to the ground can help us find the cause.  For right should abduction, the LOAD (in the frontal plane) includes adduction of the scapula, right lateral flexion of the thoracic spine, adduction of the left hip, and eversion / pronation of the left subtalar joint.  Dysfunction anywhere along this “path” can cause impingement.

When looking for probable suspects on the EXPLODE side of the Principle, this blog will focus on the sagittal plane.  If the client has pain at the end range of shoulder flexion when reaching overhead, dysfunctions that limit the EXPLODE must be identified.  The lack of posterior rotation of the scapula, thoracic spine extension, and hip extension are all potential causes.  The acromion will not move out of the way without posterior rotation of the scapula. The rotation of the scapula will be restricted by the rib cage if the thoracic spine does not extend enough.  Tightness of the hip flexors limiting extension will influence thoracic extension.

The ability to assess all of the joints in each of the three planes (6 directions) of motion is provided by the 3D Movement Analysis and Performance System (3DMAPS).  In the insufficient LOAD (frontal plane) example, the Right Opposite Side Lateral Chain would show deficiencies.  In the failure to EXPLODE (sagittal plane) example, one or both of the Anterior Chains would reveal the dysfunction.  If you want to learn how to identify and resolve these types of Chain Reaction problems, consider becoming certified in 3DMAPS.