Golfers’ Shoulders - Shoulder Biomechanics
Part 4 of a 7-part series
by David Ostrow, President of Body Balance for Performance
Biomechanics-the study of motion in living organisms-is the topic of this lesson. Biomechanics is a broad field. Thousands of people are performing research on how the human body moves and why it moves the way it does. At Body Balance for Performance we have taken on this study as it relates to motions of the golf swing. Let’s take a look at the biomechanics of the shoulder and shoulder girdle. To do this we need to apply here what we learned earlier about shoulder anatomy.
Every shoulder is has four joints, the sternoclavicular joint, (SCJ), the Scapulothoracic joint (STJ), the acromioclavicular joint(ACJ), and the glenohumeral joint(GHJ).
The SCJ is the joint between the collar bone and the breast bone. There is a small cartilage disc in this joint. It acts as a cushion. There are ligaments around the joint and muscles that cross it and control motion of the collar bone. Basically the collar bone rotates. If you unhooked a metal clothes hanger and then unbent it, you would have the approximate shape of the collar bone. Now, hold either end of the hanger and rotate one end…the other end rotates in a larger motion. This is how the collar bone works. It functions as a fulcrum for the movements of the shoulder blade. It also keeps the shoulder on the side of the body. If we did not have a collar bone, our shoulders would point forward like the shoulder of a cat or a dog.
At the other end of the collar bone is the ACJ. This joint is the one injured when someone “separates” their shoulder. This is a common football injury. There is a small cartilage in this joint, too. This is a fairly rigid joint. Its main purpose is to meld the collar bone and the scapular together into one semi-rigid structure. As with the sutures in the skull, there is not much movement in this joint. This, together with the rib cage, and upper spine, is called the shoulder girdle.
The next joint to look at is the STJ. This is the articulation of the shoulder blade on the ribs. This is a joint that allows sliding motion. The shoulder blade slides and rotates along the ribs to allow upward rotation of the glenoid fossa. This moves the acromion to out of the way to allow a great deal of arm motion without impinging the humerus on the acromion.
Finally we have the GHJ. This is the shoulder joint. It is a ball and socket joint. It is the most mobile joint in the human body. Ranges of motion of the shoulder are 180 degrees for forward flexion and sideways abduction, 90 degrees of inward and outward rotation, and 45 to 80 degrees of across the body during adduction and backward extension. There are three degrees of freedom in the GHJ. That means that the joint moves in all planes of motion. The knee has two degrees of freedom. The hip has three degrees of freedom. It also has a much deeper socket and a rigid pelvis that it attaches to so it is only about 50 percent as mobile as the shoulder joint.
Let’s look at the motion of the shoulder complex in the golf swing. On the backswing, the trailside shoulder moves through GHJ abduction and external rotation, the scapula must move down and across the back and rotate slightly upwards, and the collar bone must undergo posterior rotation. The lead-side shoulder adducts, and internally rotates. The lead side scapula moves up and forward. To do this, there needs to be coordinated motion between the shoulder blade muscles, chest muscles, rotator cuff, and the upper arm muscles. That’s it. Simple right? It is if the shoulder girdle and GHJ are stable with balanced muscle function and normal mobility.
Here is how the shoulder can break down. If the muscles that support the shoulder blade or collar bone are not balanced correctly we end up with poor scapular motion and limited arm motion in the backswing. For example, if the chest muscles are tight and the upper back muscles are weak, the shoulder blade will migrate laterally and up, with a forward tipping. You will know this is a problem because the lower corner of the shoulder blade will stick out a bit and the shoulders will look rounded. The problem with this imbalance (named lower cross syndrome) is that it limits shoulder motion in the golf swing and makes the shoulder more susceptible to injury. It can also lead to many golf maladies, such as “over the top” and “flying elbow” to name a few.
If the ligaments and capsule of the shoulder are tight, as in a “frozen shoulder,” the humeral head will drive up into the acromion process and you will experience rotator cuff irritation at the top of the swing. On the back swing this can cause shoulder pain. It can also lead to “flying elbows,” “over the top,” limited back swing rotation,” “reverse spine angle,” and many other issues.
If there is limited motion in the shoulder complex on the downswing side, you might need ice, not hot sauce, for your “chicken wing.” You will probably decelerate early as there is not enough room to accelerate fully, and this could lead to a shoulder injury.
Short swing on the back swing or downswing sides are signs of shoulder dysfunction. Limited width of the swing is also a sign of a shoulder dysfunction.
Golfer, this is important to you. If you have an imbalance in the shoulder complex, you will develop degenerative conditions and injuries in your shoulder. You will see compensatory motions, and you will struggle to make meaningful change to your swing motion, even if you practice for hours and really understand what you are trying to accomplish. Our experience has told us that if we resolve these imbalances, most shoulder pain can be prevented or at least resolved. Finally, improving shoulder girdle muscle balance will improve the efficiency of your golf motion.
The anatomy of the shoulder complex helps us understand how the region should move and gives us a road map to restore normal motion; that is, normal biomechanics of the area. Once we have an assessment of the biomechanical situation in the region, we can design and implement an exercise or training program to restore normal biomechanics and therefore normal motion. This is how we eliminate shoulder pain and improve the results of the golf swing. Biomechanics are a key, maybe the key, to understanding and fixing the shoulder complex.
Please email me at firstname.lastname@example.org if you have any questions.
Here’s to your healthy shoulder and good golf.
David Ostrow is the President and CEO of Body Balance for Performance, Inc. He has been a physical therapist for 22 years. David is considered by many golf industry professionals to be an expert in golf fitness. David has spent his career developing a well defined, effective approach for restoring the human body to full function. His eclectic approach to the body comes from his diverse training with many of the leaders in physical therapy education including Rocabado, Maitland and Callaway.
David has taken what he learned from the masters and created a complete clinical system, integrating it into Body Balance for Performance. Check out his Golf Fitness Training Programs