Age-related changes start to make themselves felt around the age of 40 or 50 years of age. This is because what happens in the upper body mimics what happens in the lower body — specifically the low back and the knee. Muscle tissue is lost, collagen develops age-related changes, in that it becomes less pliable and more vulnerable to injury. In the shoulder, this manifests as rotator cuff injuries, and labrum injuries.
Because the neck and cervical spine usually undergo degenerative changes also, those result in functional impairments to the shoulder. To have a long and active life you must exercise every part of your body’s structure and balance every area in terms of strength, flexibility, and proprioception.
This becomes ever increasingly important as you age, because of the age-related changes but also because of prior injuries or weak links becoming more prominent.
The shoulder is more susceptible to imbalances in strength and flexibility than any other joint, largely because of its structure. Picture a shoulder joint like an oversized golf-ball on an undersized tee. The hip is a ball and socket joint too but it has a much deeper socket than the shoulder. This is because although the hip can move through a fairly large range of motion, the shoulder’s range is that much more significant.
The glenoid socket of the shoulder is so shallow that only one-third of the humeral head sits in it, so although the shoulder is extremely mobile, it lacks the lock down stability of the hip. Simply put the shoulder relies on soft tissue to stabilize it more so than other major joints do. You can and should work all muscles of the shoulder to stablize and strengthen it.
Those muscles include the trapezius which works to retract the shoulder blade, the rhomboids which also help pull back the shoulder blades and are important to maintain good posture, the pectoralis major that covers the chest area and pull the shoulder inwards and down, the latissimus dorsi which are the huge back muscles that pull the upper arm down and back, the deltoids which allows the shoulder to flex and extend and move away from the sides of the body and the rotator cuff muscles of which there are four.
The rotator cuff muscles are the most famous or perhaps the most infamous shoulder muscles because they often are the cause of pain. They help raise the arm away from the side of your body and they help the shoulder rotate in sundry directions.
The rotator cuff’s primary function is to stabilize the humeral head (the ball part) against the glenoid socket. Unlike the larger muscles connected to the shoulder’s movement, the rotator cuff muscles are small little straps of muscle that can be easily overworked, fatigued and torn. While the large deltoid muscle is the power generator, the rotator cuff muscles are the fine motor muscles.
The four are the supraspinatus, the infraspinatus, the teres minor and the subscapularis. Of the four, the supraspinatus is the most likely to tear. It is active in any movement that involves elevation of the upper arm (think working out overhead, tennis, throwing a ball, golf, etc.) The infraspinatus also stabilizes the upper arm in the socket and accounts for the majority of external rotation strength at the shoulder.
The teres minor provides the other 40 percent of the strength needed to externally rotate the shoulder. The subscapularis rotates the shoulder internally.
Rotator cuff injuries usually occur in the dominant shoulder, and the usual course of treatment includes rest and limited overhead activity, short term use of a sling (because the shoulder can get “frozen”), anti-inflammatory meds if needed and strengthening exercises.
Prevention is always better than a cure and the preventive strategy is a balanced workout that strengthens all muscles of the joint so that the shoulder is supported and stable and there is no weak link.
Dr. Jane Riley, is a certified personal fitness trainer, nutritional adviser, behavior change specialist and orthopedic exercise specialist.