Shoulder Capsule Anatomy
Introduction
The shoulder girdle is the most mobile joint in the body, the Glenohumeral joint and Scapula complex work together to allow truly ridiculous ranges of movement. This is likely because when we descended from the trees and transitioned to bipedal walking, the joint no longer had to be weight-bearing and eventually evolved to the demands of carrying, running and throwing.
Most people know about the muscular structures of the shoulders, Deltoids, Pectorals etc, but few are particularly aware of the ligamentous structures deep in the shoulder joint, specifically around the Glenohumeral joint. Such structures cannot be seen, and therefore often go unnoticed.
From Left to right. The Shoulder Capsule Outer Layer, The Synovial Membrane Inner Layer, Isolated Shoulder Capsule
The Capsule
The primary topic here is the shoulder capsule, this structure is a ring-shaped piece of connective tissues that encompasses the humeral head and the Glenoid cavity of the Scapula. The capsule is double-layered, the inner Synovial Membrane secretes Synovial fluid to help keep the joint well lubricates to allow free and smooth movement. The second outer layer of the capsule is the fibrous but loose connective tissue that provides passive stability for the Glenohumeral Joint.
This capsule, for the most part, best left alone. Stretching can often stress the capsule too much and cause further instability of the shoulder. The anterior (front) of the capsule provides stability for the anterior of the shoulder, and likewise for the posterior (back). Excessive stretching can reduce the capsules ability to provide passive stability. Chest stretches are common in swimming pool preparation, before races and some perform them every day, this is simply a poor way to go about improving mobility in the body and is potentially dangerous for swimming athletes. Stretching every day just shows how poor this method is for increased mobility. Do you have to swim Backstroke every single day to make improvements? No. Do you need to Deadlift every day to preserve force production capacity? No. So why does this thought process apply to stretching? Madness.
The Worst Stretches You Can Do
Door Way Chest Stretch: This places huge stress on the anterior capsule. You can mobilise the chest in much more productive ways than simply stretching. If you must use chest stretches, keep the arm straight.
Across Body Stretch: a classic of most warm-ups, it’s trash. Ditch it. It stretches the posterior Deltoids and upper back muscular which is certainly something swimming athletes don’t need for the most part.
Sleeper Stretch: not only does this stretch place a great strain on the posterior capsule (tissue so thin you can pass light through it), it’s also an impingement position meaning you increase the risk of pinching other tissues of the shoulder such as the Supraspinatus tendon or Biceps tendons, causing inflammation, painful ranges of motion and decreased time in the water.
Take time to understand the shoulder in all its complexity and beauty, it’s a truly fascinating joint that cannot be trained or modified without a thorough understanding of anatomy and how the shoulder moves.
Left to right. Door Way Chest Stretch, Cross Body Stretch and Sleeper Stretch.