Risk Factors for Asymptomatic Rotator Cuff Tears to Become Symptomatic.

PPTs will be measured on three local locations around the shoulder (supraspinatus, infraspinatus and posterior deltoid). Additionally, two more distal PPTs will be measured (erector spinae and triceps surae).

The AHD is the shortest linear distance between the inferior edge of the acromion and the superior edge of the humeral head. This will be measured during rest and during muscle activity.

Passive and active scaption - passive external rotation in supine position with arm in 90° abduction - passive internal rotation in supine position with arm in 90° abduction.

45° scapular elevation - external rotation - internal rotation - hand grip strength

The conditioning stimulus will comprise of immersion of the foot until the proximal ankle (level of the malleoli) in a hot circulating water bath of 45.5°C during 1 minute. The test stimulus will comprise of pressure pain threshold (PPT) assessments (as described above) before and after completion of the conditioning stimulus.

The CSI measures the participant's Central Sensitization Syndrome related symptoms. The higher the score, the more signs of central sensitization are present.

The TSK evaluates the general pain related fear of movement. The higher the score, the higher the pain related fear.

The SF-36 evaluates the general health and well-being or quality of life. Contains a physical and mental component score. A higher score expresses a better health condition.

The SPADI evaluates the pain and restrictions in activities. The higher the score, the worse the symptoms.

DASS-21 evaluates the depression (7 items); anxiety (7 items) and stress (7 items). The score will be multiplied by 2 to have a comparable score with the DASS-42.

The IPAQ will be used to evaluate the physical activity level of the participants. This questionnaire contains 31 questions in 5 domains: 1) physical activity during work; 2) physical activity concerning transport; 3) physical activity by doing household chores; 4) physical activity concerning sport activities; 5) sitting time.

Seven questions to ask for sleep problems.

The GSES measures (10 statements) how a person deals with stressors/difficult situations in life. The scale is about a person's self-confidence that his or her actions are responsible for successful outcomes or, in other words, that one has control over challenging demands imposed by the environment.

Electromyographic activity will be measured during AHD measurement in rest and during activity. The amplitude of the EMG activity from the three parts of the deltoid (anterior, middle and posterior part) will be obtained. The unit is volt. EMG activity will be expressed as percentage of the MVIC (maximal voluntary isometric contraction).

This is a non-invasive and real time assessment of tissue mechanical properties that measures the elasticity of the muscles/tendons. The higher the shear modulus/young modulus/shear wave speed, the higher the stiffness. SWE assessment will be done for the followings muscles: supraspinatus, infraspinatus, anterior and posterior deltoid.

The supraspinatus muscle thickness will be measured on two locations: 1) midpoint of the line cranial to the spina scapula; 2) 2 cm medial to the midpoint of the line cranial to the spina scapulae. One longitudinal and one transverse measurement at each of the scanning sites will be performed. This will be measured in mm.

The HGD is the distance between the most posterior point of the humeral head and the posterior glenoid. This will be measured in mm.