The shoulder joint is arguably the most important part of a swimmer’s body. Strong, flexible shoulders are essential for generating propulsion and maintaining proper arm mechanics in the water. Experiencing shoulder pain when swimming can be detrimental in terms of lost training time and missed competitions - so let’s look at why it happens and how to prevent it.

What Is Swimmer’s Shoulder?

Swimmer's shoulder is a colloquial term that is often used to describe shoulder pain and injury in swimmers. It is a common overuse injury associated with the repetitive motion and strain placed on the shoulder during swim training and competition. Swimmer's shoulder typically involves inflammation, irritation, or injury to the structures in and around the shoulder joint.

Causes of Swimmer’s Shoulder

Since it’s a catch-all term for shoulder pain from swimming, there is not one definitive cause of swimmer’s shoulder that we can point to. Therefore, it’s important to consider the problem from multiple viewpoints to try and best encapsulate what might be happening and why. 

Impingement

Shoulder impingement occurs when the rotator cuff tendons become compressed or pinched between the bones of the shoulder, particularly the acromion (a part of the shoulder blade) and the head of the humerus (upper arm bone). There are two differentiated classes of shoulder impingement; primary and secondary.

Primary impingement refers to variations in anatomy that could cause impingement to occur; i.e. bony protrusions that narrow spaces in and/or around the shoulder joint. Secondary impingement refers to functional reductions in these and other spaces as a result of things like muscle imbalances, altered joint mechanics and other dynamic factors. 

Without diagnostic imaging, primary impingement can be difficult to discern. Interestingly, though, analysis has shown that during the front crawl, the shoulder is impinged for about 25% of the total stroke time. So whether we like it or not, on average, we’re putting the shoulder into a repetitive state of impingement with almost every stroke we perform while swimming.

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Instability

Compared to recreational participants, elite level swimming athletes tend to have greater glenohumeral joint laxity. The glenohumeral joint is where the ball of your upper arm bone (humerus) inserts into the glenoid fossa (socket) of the scapula. This basically translates to better shoulder mobility, sometimes to the point of gross instability in the joint.

The ability to swim efficiently requires a high degree of flexibility in the shoulder. With this in mind, it’s no surprise that extremely competent swimmers are inherently predisposed to excess mobility, in what is already the body’s most mobile joint. Finding the right balance between laxity and support, though, is tricky when it comes to swimming.

Hyperflexibility may be desirable for performance, but it may also leave other structures in the shoulder more open to wear and injury. Lack of strength training in the programs of many triathletes contributes to this problem, because swimming alone does not adequately challenge the shoulder muscles to develop the necessary levels of balance and stability.

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Overuse

Relating to both of the first two causes is the problem of overuse. Someone who trains swimming competitively will take each shoulder through hundreds of thousands of revolutions over the course of a year. This has the potential to bring about pathological changes in the anatomy of the shoulder, regardless of its preceding health. 

Tendinopathy in the supraspinatus, a rotator cuff muscle that initiates abduction (elevating the arm away from the body), is commonly found in people experiencing swimmer’s shoulder. Functionally, high degrees of internal rotation, beyond normal physiological ranges, are required throughout an optimal freestyle stroke; referred to by coaches as the “high elbow position”.

It makes sense that this heightened proportion of internal rotation compared to external rotation, coupled with repetitive flexion, renders the shoulder more susceptible to dysfunction and injury. Relative weakness in the external rotators can lead to an inability of the rotator cuff to properly control humeral head positioning, possibly leading to secondary impingement of the shoulder.

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Solutions for Swimming Shoulder Pain

Where there are many causes, there are many solutions. Let’s turn our attention now to ways you can go about addressing swimmer’s shoulder and preventing it from happening in the future. 

Stretching & Mobility

While excessive mobility was one of our potential causes for swimmer’s shoulder, that was primarily present in elite level swimmers. For many of us, lack of mobility may be the more likely culprit. Any part of the body is likely to speak up when you start forcing it into positions it’s not ready to go in. Stretching and mobility work can make these positions more attainable. 

Strength Training

As previously mentioned, swimming alone will not challenge the shoulder to develop in a balanced way. The freestyle stroke is exponentially skewed towards internal rotation. We need a variety of exercises that rotate the shoulder externally, as well as take it through all its other ranges of motion under load. This is the only way to build stability in a joint that favours laxity.

Cross Training & Periodic Rest

Swimmer’s shoulder is particularly problematic in people coming to triathlon with a swimming background. The bottom line is, as a triathlete, you have three sports to train for. If shoulder pain is becoming a problem while swimming, focus on building up the other two disciplines, while at the same time taking planned, designated and regular periods of rest from the pool.

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Written by Eric Lister – Certified Personal Trainer & Corrective Exercise Specialist