Patients with rotator cuff tendinopathy make up a large part of the population in physiotherapy practice. The rotator cuff, a shoulder muscle group, plays an important role in causing pain. Tendons suffer large compression and friction, which can lead to degeneration of these tendons. Rehabilitation often leads to unsatisfying results.

In Achilles and patella tendinopathy, a new training program called eccentric training has shown very good results. Eccentric training contains exercises during which a force has to be resisted while the muscle lengthens instead of shortens. This would have a larger influence on tendon tissue. Some small studies also show promising results of eccentric training in patients with rotator cuff tendinopathy but the mechanisms behind these results remain unclear.

To investigate this, 30 patients with rotator cuff tendinopathy and 30 healthy subjects will be evaluated before and immediately after performing the exercise. Three measurements will be done: ultrasonographic measurement of tendon thickness, power Doppler imaging and measurement of microcirculation around the tendon with Oxygen to see. All measurements are non-invasive, pain free and without risks for the human body.

Inclusion Criteria Patients:

• Male/ Female
• 18-40 years old
• Unilateral shoulder pain for at least 3 months
• Pain of at least 3/10 on a visual analogue scale
• Painful arc or pain at end range abduction
• 2/3 impingement tests positive
• 2/4 resistance tests positive
• Pain at insertion rotator cuff

Exclusion Criteria Patients:

• Spurling test positive
• Shoulder surgery in the past
• Osteoarthritis shoulder
• Full thickness ruptures

Inclusion Criteria Healthy subjects:

• Male/ Female
• 18-40 years old

Exclusion Criteria Healthy subjects:

• Shoulder pain during the last 3 months
• Shoulder surgery in the past
• Neck pain or disability
• Systemic disease (e.g. Marfan, Ehlers Danlos,…)