Some people train their shoulders to attain the ideal of two cantaloupe shaped protrusions on their upper arm. Other people appear to delight in abusing their shoulders, repeating throwing or swinging motions until their arm nearly falls off. Others fear injury and refuse to do any shoulder exercise other than rotator cuff rotations with the band. To determine a sensible approach to training the shoulder we will focus on the structure and optimal function of the shoulder and related body parts (Part 1) and then delve into the training implications of these findings (Part 2). As an example, we will discuss the situation in which the shoulder acts to move the hand with speed, as in swinging a racquet or club, striking and throwing.
The gleno-humeral joint is the true “shoulder joint”, where the arm articulates with the trunk, and the point of action of the famous rotator cuff muscles. But movement at the shoulder is directly influenced by movement of the scapula, or shoulder blade, and the thoracic spine, the large middle region of the spine. For example, at the end of a throw like Mr. Johnson’s, above, the gleno-humeral joint is flexed forward, adducted across the body and somewhat rotated internally. This is accompanied by forward movement and external rotation of the scapula and rotation in the thoracic spine. If only the gleno-humeral joint were involved, the range of motion would be limited but the interaction of each of these regions accounts for the unparalleled mobility of the shoulder complex. Importantly, even these three regions are not isolated. The muscles and related connective tissue in the front and back of the shoulder complex are interwoven with neighboring tissues to link the whole body together. The rear shoulder tissues connect diagonally across the back to the opposite buttock (Take a gander at Figure 1 below). The front shoulder tissues are closely related to the abdominals and the front part of the hip on the opposite leg (Figure 2 below). The physical connection between the shoulder complex and the hips indicates that the shoulder serves as a point in the transmission of force generated from the powerful legs and hips. Indeed, the position of Randy Johnson’s legs in the photo hint at the interplay of the shoulder and legs. A well functioning shoulder then cannot only generate force on its own but it can also impart the force of the whole body into the hand or implement while also controlling the hand.
If the shoulder is to allow maximum force to flow into the hand, it must maintain adequate mobility and stability. Limited mobility in the entire shoulder complex, or at any of its constituent regions, will reduce the shoulder’s effectiveness by reducing the range in which to generate force. In the same way, cracking a short whip will generate less energy (i.e. sound) than cracking a long whip.
Furthermore, limited mobility in the shoulder complex can contribute to injury if the legs and hips can generate enough force to compel the shoulder to move beyond its restricted range. Likewise, instability at the shoulder will reduce force transmission as energy gets consumed at the joint. Consider the can and string telephones that kids can make. These only work when the string is tight because energy is wasted on excessively vibrating the loose string. An unstable shoulder joint acts the same way; the joint itself consumes energy instead of transmitting it to the arm. Instability can contribute to injuries that involve physical movement of the structures, such as a shoulder dislocation, and also injuries that result from decreased ability to control the hand. Mobility and stability interact to generate, transmit and control force going into the hand and are the foundation for increased performance in any activity requiring throwing, striking or swinging.
Next blog we will explore how to train the shoulder to succeed in generating, transmitting and stabilizing force. For more questions on shoulder movement and actions please contact persona fitness trainer Hunter Spencer.