Get the Balance Right The importance of the scapula and rotator cuff muscles in shoulder movement

Chronic shoulder problems often occur because of an imbalance of shoulder muscle activity caused by incorrect exercising and poor posture. Effective coordinated movement of the shoulder complex requires a certain balance of strength between the large prime mover muscles and the smaller stabilizing muscles. Most chronic shoulder problems result from poor function of these smaller rotator cuff muscles of the shoulder and the muscles which control the scapula.

Gym goers who focus their training on the large mirror muscles such as the pectorals and deltoids tend to lose this stability as well as those who sit with poor posture, hunched and round-shouldered over a desk for long periods, overworking the larger muscles and underworking the smaller ones. The relative weakness of these stabilizers causes the larger muscles to dictate the position and motion of the head of the humerus within its socket. When it is not well centered in this socket throughout shoulder movement, problems are almost guaranteed to arise.

What can be done to prevent this?

More often than not, chronic shoulder problems are thought only to affect those overhead athletes who religiously perform repetitive, complicated throwing actions at maximal force. Yet javelin throwers and cricket bowlers are not the only people who suffer from problems of shoulder impingement and rotator cuff tears. Indeed, the high prevalence of this type of injury within the general populace reflects an overlooked concept surrounding the shoulder getting the balance right. This balance refers to the scapular and the musculature that encapsulates it and the large mirror muscles such as the deltoids and pecs. It is no wonder why problems tend to arise when exercise is focused upon strengthening the large, prime mover muscles such as pectorals and deltoids. While these mirror muscles sought after by gym-goers improve and grow under these regimes, the strength of the rotator cuff muscles and scapular stabilizers is compromised.

Without effective coordination of the muscles of the shoulder complex, day-to-day activities such as gardening can produce the same problems often experienced by these overhead athletes. Indeed the high prevalence of problems such as shoulder impingement and rotator-cuff tears reflect the importance of the scapular in all shoulder movement.

An effective exercise program needs to include exercises to promote scapula stability primarily than rotator cuff strength. This provides a good base for activities that involve lifting the arm, whether it be exercising or activities of daily life. In a nutshell, the shoulders and scapula should be drawn back and down to facilitate a good balance of shoulder muscle activity when lifting the arm. Good posture facilitates normal synchronous movement. Poor posture with head forward and rounded shoulders lead to inactivity and weakness of scapula and upper back muscles, so important for the good, pain-free function of the arm.


knowledge … self-management … prevention