This article is on the ligaments of the glenohumeral joint in reference to “resisting” external rotation forces. Using cadavers, Kuhn and others isolated the glenohumeral ligaments in various positions of external rotation of a neutral or Abducted shoulder then applied incremental forces to anterior-chain tissues (subscapularis and/or long head of the biceps brachii).
Interestingly, two things were found: The capsule works as a “cylinder” that resists external rotation forces and secondly, the biceps brachii plays a role as a dynamic stabilizer during abduction by resisting external rotation forces. This tells me that if things break down in the shoulder (bursitis, tendonitis or rotator cuff tears), then not only will the biceps brachii and glenohumeral (GH) ligaments be the last ditch defense in stabilizing the glenohumeral joint, but will also be responsible for controlling external rotational forces.
Here’s the practical app: This can be very useful to understand with the many externally rotated positions many people place themselves during training: Shoulder presses, lat pulldowns, pull ups, reaching, chopping. By strengthening the scapulothoracic (ST) joint, we can spare repetitive stress on the tissues within and around the GH joint and encourage a fully functioning shoulder complex. Let’s start conditioning the mid/lower traps, rhomboids, serrati anterior to help propagate the forces from the lower body and trunk to into the shoulder with reduced stress on the GH tissues!
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