As fitness professionals we are always on the look out for ways to improve one thing: results. In medical professional world, if you don’t produce results, you don’t have a business. In this post, you will learn why shoulder issues are so prevalent, why you should care about the upper extremity mismatch, and how this information will improve the results of your training sessions. Ultimately, a better understanding of the shoulder girdle and upper extremity mismatch will enable you to more safely and effectively train the upper body without risk of shoulder injury.
The “upper extremity mismatch” is directly linked to the reason why so many people suffer with shoulder and rotator cuff issues. The shoulder joint is where the most problematic mismatch occurs in the upper extremity. This mismatch is the cause of many of the shoulder pathologies seen by medical and fitness professionals today. So, what exactly is the “upper extremity mismatch”?
To understand this mismatch, a review of shoulder anatomy is required:
The glenohumeral joint, or shoulder joint, is inherently unstable. This is caused by poor joint congruency and it allows humans to have great shoulder mobility. A review of the shoulder girdle anatomy demonstrates the most significant upper extremity mismatches.
One mismatch can be attributed to the switch in our shoulder blade position that occurred as we became bipedal. Our shoulder blades changed from facing upward to facing more sideways. Subsequently, this seemingly small change made overhead motion more difficult due to the position of the acromion process. The process is now positioned to impinge the superior rotator cuff tendons with overhead motion.
The entire shoulder complex was designed to move as one unit. Motion of the upper extremity was not isolated. The upper arm bone, shoulder blade and clavicle all contributed to upper extremity motion. Today we perform many tasks in which we compromise this mechanism by impeding shoulder blade motion when performing upper extremity tasks.
You might wonder how we previously adapted to this excessive force production. Gravity is the answer. When we were on all fours, gravity assisted in shoulder joint compression. Along with the rotator cuff this mechanism provided a stable fulcrum to allow the bigger muscles around the joint to cause motion without the joint actually subluxating. As we transitioned to bipedal animals we lost this part of the stabilizing mechanism and further adaptation was not required (Lieberman, 2013).
In a quadruped motion, gravity assisted with shoulder joint approximation. Thanks to the compression forces created by closed chain motion, the integrity of the joint was maintained. This compression was important during times of significant muscular force production. Once the glenohumeral joint evolved to utilize gravitational compression, it was able to sacrifice structural stability for mobility. The rotator cuff musculature is designed to assist in this stabilization process, not be the sole mechanism as it was subsequently forced to do as we became bipedal.
In today’s modern world we use our upper extremities in an unfixed open chain, meaning that we function without the assistance of gravitational compression. This adaptation places a great deal of stress on the rotator cuff leading to deterioration and overuse. To overcome these structural mismatches we must train utilizing the compressive force of gravity when exercising the major muscles of our upper extremities. This can be done safely and effectively through closed chain exercises. Additionally, it is highly recommended that we avoid repeated and loaded overhead motions and stop bench pressing.