Swimmer’s shoulder consists of a specific overuse injury of the shoulder tendons. Swimmer’s shoulder occurs when the tendons of the shoulder suffer from inflammation and swelling, compressing with the nearby bones, muscles and other tendons. Some physicians also know Swimmer’s shoulder as shoulder impingement, subacromial impingement or painful arc. 

Inflammation tends to affect the tendons in the rotator cuff (a group of muscles and tendons that hold the arm bone into the shoulder joint). These tendons may put pressure on the top part of the shoulder blade, also known as the acromion. This friction on the shoulder blade may then lead to bone spurs developing.