Swimmer's shoulder is an injury of the shoulder's muscles and tendons due to overuse or bad swimming technique. It manifests itself as pain and inflammation.
Even though swimming is a low-impact sport, it uses the shoulders extensively and puts them at risk. For example, a shoulder rotates about 10 times when swimming 25 yards of freestyle. That means that for a moderate 50 lengths workout, each shoulder rotates about 500 times. Multiply this by a few swim sessions per week and you see that it quickly adds up.
The shoulder is the most mobile joint of the body. This mobility is due to the shoulder's anatomy. It is like a golf ball (the head of the upper arm bone, the humerus) placed on a tee (the lateral scapula) held in place by a set of stabilizing muscles and tendons called the rotator cuff.
If the rotator cuff muscles grow tired or incorrect technique is used, the joint can become lax and the humerus then moves incorrectly and can injure soft shoulder tissues.
The injury can be caused by incorrect technique. In freestyle, this is the case if the hand enters thumb first or crosses the middle of the body when it extends to the front.
Over training, sudden increases of training volume or intensity can also lead to this condition, as the rotator cuff muscles tire more quickly than the propulsive muscles and the articulation then becomes unstable.
Unbalanced strength and flexibility development of the muscles is also a cause, as well as unilateral breathing in freestyle, overuse of swim paddles and overzealous stretching.
Swimmer's Shoulder Prevention
First of all, make sure you swim with correct technique. A qualified swimming professional or experienced swimmer can asses your stroke and highlight mistakes. For example, in freestyle, make sure that you enter the hand flat in the water during the recovery and that it doesn't reach past the middle of the body during the pull phase.
You shouldn't overtrain or train with tired muscles, as this means that the stabilizing muscles of the shoulder don't work correctly anymore and the shoulder can be injured. Also avoid sudden increases in amount or intensity of the swim workouts.
Avoid the overuse of swim paddles, as they put additional strain on your shoulders. And don't kick too much holding a kick board with arms extended forward, as it puts the shoulders in a weak position.
Swimming especially strengthens your chest muscles and the shoulder's internal rotators. Those then become stronger but also shorter than their antagonists.
To compensate for this , you should stretch the chest and the shoulder's internal rotators and strengthen the scapular stabilizers and the shoulder's external rotators. More about this in the related pages section below.