Background: Subacromial impingement syndrome (SAIS) is one of the most common causes of shoulder pain. The subacromial-subdeltoid (SAD) bursa is regarded as a common potential shoulder pain generator. Differentiating the specific acromio-humeral interval (AHI) tissues responsible for pain generation is challenging and no specific clinical examination testing exists to differentiate SAD bursa from the rotator cuff tendons as pain generators. Corticosteroid injection (CSI) within the AHI is a mainstay of treatment for SAD bursitis and rotator cuff tendinopathy. No study to date has examined a specific test associated with successful responsiveness from a CSI targeting the SAD bursa in the AHI in subjects with shoulder pain.