The purpose of this study is to investigate and compare the long term effects of traditional and modified static cross-body posterior shoulder stretching training in individuals with subacromial impingement syndrome (SIS) having glenohumeral internal rotation deficit (GIRD). Modified cross body posterior shoulder stretching group will receive static stretching in the modified cross-body stretching position and standard physiotherapy program. The traditional cross body posterior shoulder stretching group will receive static stretching and standard physiotherapy program. The Control group will receive only sham stretching and standard physiotherapy program.

SIS is the most common cause of pain and shoulder dysfunction. The etiology of SIS depends on many factors including tightness of the posterior shoulder structures. Posterior shoulder tightness (PST) narrows the subacromial space and forces anterior-superior migration of the humeral head over the glenoid fossa and, it could cause limitation of the internal rotation (IR) and horizontal adduction range of motion (ROM). GIRD is known as loss of IR ROM in the glenohumeral joint. In the SIS, limitation IR ROM has been reported. Supraspinatus tendon thickness can change, subacromial space may become narrower and joint position sense (JPS) could be decreased in SIS patients. The effectiveness of traditional static cross body posterior shoulder stretching on various parameters such as shoulder rotational ROM or pain was studied and proved in the literature. Traditional static cross body posterior shoulder stretching could reduce subacromial symptoms and improve shoulder ROM with some disadvantages such as inadequate control of the scapula and glenohumeral rotation. To prevent accessory abduction of the scapula, restrict the external rotation ROM of the humerus and provide isolated posterior capsule stretching, Wilk et al. (2013) recommend the use of modified cross-body stretching for IR ROM increase. In the modified cross-body position, the patient is positioned in a more advantageous way. In the literature, although modified cross-body posterior stretching seems effective on SIS symptoms there is no research about the comparison of the long-term effects of the traditional and modified static cross-body posterior shoulder stretching exercises in individuals with SIS having GIRD. Therefore, whether modified stretching is superior to traditional stretching is not known. Our study aims to investigate and compare the long term effects of the traditional static cross-body posterior shoulder stretching exercise and modified static cross-body posterior shoulder stretching exercise in individuals with SIS having GIRD on shoulder IR ROM, GIRD, PST, pain, external rotation ROM, JPS, subacromial space, supraspinatus tendon thickness, posterior capsule thickness, the occupational ratio of the supraspinatus tendon in the subacromial space, muscle strength and shoulder function and disability level. Stretching groups will receive either traditional or modified static cross-body posterior shoulder stretching exercise and standard physiotherapy program. The Control group will receive only sham stretching and standard physiotherapy program. Standard physiotherapy program consists of electrotherapy, posture, proprioceptive, and strengthening exercises. The treatment program will be performed 5 days a week under the physiotherapist's supervision and 2 days a week as a home program for 8 weeks.

Inclusion Criteria:

• Diagnosis of subacromial impingement syndrome
• Glenohumeral internal rotation range of motion of the affected shoulder should be less than other shoulder and bilateral shoulder internal rotation range of motion difference should be ≥15 º
• Pain with resisted arm elevation or external rotation as well as a minimum of 3 of 5 positive subacromial impingement syndrome tests, painful arc, pain or weakness with resisted external rotation, Neer, Hawkins and Jobe tests .
• Ability to complete the entire study procedure

Exclusion Criteria:

• A 50% limitation of passive shoulder range of motion in >2 planes of motion
• Pain >7/10
• A history of fracture to the shoulder girdle
• Systemic musculoskeletal disease
• History of shoulder surgery,
• Glenohumeral instability (positive apprehension, relocation or positive sulcus test) or positive findings for a full thickness rotator cuff tear (positive lag sign, positive drop arm test, or marked weakness with shoulder external rotation)

All of the participants must have subacromial impingement syndrome with glenohumeral internal rotation deficit (Bilateral IRROM difference ≥ 15º )