The shoulder and hip joints are remarkably similar in structure.
They have matching bones and muscles, but since we evolved from walking on all fours to walking upright, the load on the arms decreased and the bones, ligaments and muscle became smaller as we sacrificed strength for an increase in mobility.
The increase in mobility gave people a much greater selective advantage for survival being able to manufacture tools and shelter, but it can be a liability for certain sports that require overhead movements.
The shoulder is normally described, like the hip, as a ball-and-socket joint, though the socket is very shallow, and the ligaments, capsule and muscles are much smaller than the hip and do not provide as much support.
Because of this, the muscles, ligaments and joint capsule play an extremely important role in protecting the shoulder joint. Add to this the fact that complex overhead shoulder movements, like pitching, tennis and volleyball can load this joint and cause potential injuries.
But probably the most complex and repetitive motion for the shoulder joint is swimming. In fact over 2/3 of competitive swimmers will experience shoulder problems at some point in their sports-life. What are the contributors to this problem and how can you avoid injury?
The causes of swimmer’s shoulder usually are due to at least one of the following: training intensity, distance, recovery and stroke mechanics. Other contributors can be poor posture, excess shoulder stiffness or shoulder laxity which can all change over time with training.
The vast majority of problems are due to micro-trauma on some key structures including the rotator cuff, biceps tendon or inflammation of the bursa sac between the tendon and bone, especially considering that the number of repetitions the shoulder is subjected to in a typical training session can be several thousand for each shoulder.
This injury is called shoulder impingement and has the potential to cause very disabling shoulder pain and dysfunction in swimmers. The stroke mechanics of freestyle, backstroke and butterfly involve placing the shoulder in unstable, loaded positions during the overhead phase of the stroke while the breast stroke is much less demanding on the shoulder.
Even something as simple as having not enough rest between training or competition sessions can irritate structures and set off a cascade of problems. Once pain begins, stroke mechanics can be altered further exacerbating the situation.
The best course of action is not to train through the pain, but rather take some time off, address all the possible causes and rehabilitate well before returning to training and competition. Make sure that strength is balanced around the joint and there are no impingement signs.
Investigate core strength and stability as well since body-roll during swimming is very important – lack of roll will cause the shoulders to have to compensate and adjust, thereby causing more load on the shoulder. Most of the time swimmers are flexible enough, or even hyper-mobile. Too much flexibility can cause problems, so get your flexibility assessed as well.
Swimming is such a complex movement that you need to address injury questions fully in order to prevent long-term problems. And if you do not swim but are an overhead athlete like a baseball player, also take care of your shoulders since; although not identical to swimming, all overhead sports have the potential to cause similar injuries.
Kerry Senchyna is the founder, owner and president of West Coast Kinesiology since 1992 and is a provincially registered kinesiologist.