Shoulder pain is the third common problem, after problems of spine. Abnormal scapular kinematics, so called scapular dyskinesis, is believed to be associated with shoulder pain. Studies showed that individuals with shoulder problems demonstrate less upward rotation, posterior tilt and external rotation during shoulder movement. The shortness of the pectoralis minor (PM) is one of the factors leading to scapular dyskinesis. Short pectoralis minor has been shown to prevent scapula from tilting posterior and rotating externally during shoulder motion. The decreased scapular posterior tilt and external rotation may decrease subacromial space and result in impingement. However, although many assessment methods have been used to assess PM tightness or shortness, no study has tested the validity of these testing methods. Moreover, although stretching exercises for PM have been shown to increase the PM length, previous studies found that PM stretching exercises did not restore scapular kinematics and did not further decrease pain and improve function. Shoulder pain and discomfort has also been reported during stretching. Therefore, rather than stretching exercise, other types of treatment that can specifically increase the PM length and restore scapular kinematics may be needed. Manual therapy could specifically increase the flexibility of PM, and scapular orientation exercises could improve scapular kinematics. These types of treatment may be better options. However, to our knowledge, no study has investigated whether manual therapy combined with scapular orientation exercises could improve scapular kinematics, pain and function. Therefore, the first part of this study is to investigate which tests for length or tightness of PM can predict the scapular dyskinesis. The second part of the study is to investigate the effects of manual therapy and scapular orientation training on PM length, scapular kinematics, pain, and function in subjects with shoulder pain. In the first part of the study, 67 healthy subjects will be recruited. In the second part, 62 patients with shoulder pain will be recruited and randomized into either a PM treatment group or a control group. While no treatment will be provided for the healthy subjects in the first part, subjects with shoulder pain in the second part will receive 12 sessions of treatment in 4-6weeks, with 30-40 minutes per session. Patients in the control group will receive general shoulder strengthening exercise, while patients in the PM treatment group will have additional manual therapy and scapular orientation exercise. The measures include tests of PM length, scapular kinematics in the first and second parts, and pain and shoulder disability were also additionally assessed in the second part.

Inclusion Criteria(patients with shoulder pain) :

1. the patients with shoulder pain from 20 - 60 years old
2. Active arm elevation close to 150 degrees
3. Shoulder pain at least 3 months

Inclusion Criteria (healthy people) :

1. the people from 20 - 40 years old
2. no any symptoms or injuries on shoulder one year ago

Exclusion Criteria:

1. Adhesive capsulitis
2. Pathologies of cervical origin
3. History of acute trauma, previous surgery, or fracture in the affected shoulder
4. Corticoid injection in the last 3 months
5. Platelet Rich Plasma injection in the last 1 year
6. Other manual and exercise physical therapy in the last 6 weeks
7. Anyone suffering from neurological diseases and nerve damage
8. Vulnerable subjects