This study was planned to investigate the effect of blood flow restriction exercise training on shoulder muscle strength and muscle thickness, and to determine the change in pain and symptoms in patients with rotator cuff tendinopathy. Patients in the study group will perform the rehabilitation exercises with a pneumatic cuff and blood flow restricted. The patients in the control group will perform the same exercise program without restricting blood flow.

In recent years, one of the popular applications used for muscle hypertrophy and strength training is low-intensity exercise training called Blood Flow Restriction Training. This exercise training has been shown to allow the benefits of high-intensity training at a much lower intensity. Given the light-load nature and strengthening capacity of this training, it can provide an effective clinical rehabilitation stimulus without the high levels of joint stress. It is suggested that it will be a useful exercise alternative especially in individuals who cannot tolerate high-intensity exercise. Especially patients with shoulder pain cannot tolerate high-intensity exercises in early rehabilitation.

This study was planned to investigate the effect of blood flow restriction exercise training on shoulder muscle strength and muscle thickness, and to determine the change in pain and symptoms in patients with rotator cuff tendinopathy.

Hypothesis 1: There is a difference between exercise training with blood flow restriction and exercise training without blood flow restriction in terms of muscle strength and muscle thickness.

Hypothesis 2: There is a difference between exercise training with blood flow restriction and exercise training without blood flow restriction in terms of shoulder pain and shoulder function.

The study was designed as a randomized-controlled. In order to provide an evenly equal number of individuals and homogeneous gender distribution in the groups blocking and stratification will be used as a randomization method. The sample size was calculated to be an 8% difference in muscle thickness at the end of treatment with 80% power and 5% type 1 error. A total of 26 patients were planned to be included in the study, including 13 volunteers in each group. Patients in the study group will perform the determined exercises with a pneumatic cuff and blood flow restricted. The patients in the control group will perform the same exercise program without restricting blood flow. Informed consent will be obtained from all individuals.

Demographic information (age, gender, body mass index, dominant side, affected side, etc.) of all patients will be recorded. Shoulder pain (rest, night and activity- visual analog scale), shoulder range of motions (goniometer), shoulder function (Shoulder Pain and Disability Index-SPADI), shoulder rotator muscle strength (isokinetic dynamometer-Isomed 2000, D&R Ferstl GmbH, Germany) and supraspinatus, infraspinatus, deltoid, biceps, middle trapezius muscle thickness, and acromio-humeral distance (ultrasonography- Logiq P5, General Electrics, USA) will be evaluated before and after 8 weeks of exercise training.

In the first session of treatment, initial assessments and patient education to reduce shoulder pain (avoiding overhead activities and heavy work, appropriate posture, cold-pack application recommendation) will be performed. Exercise training will start in the second session. Individuals in the groups will have 2 sessions per week, 16 sessions of exercise training for 8 weeks. On other days, patients will continue their home exercises recommended by the physiotherapist.

The blood flow restriction training will be applied to patients in the study group, as defined in the literature, by wearing a pneumatic cuff from the most proximal region of the upper limb. Occlusion pressure will be calculated according to the formula for each patient. [Pressure = 0.4 x (systolic blood pressure) + 2.7 x (shoulder circumference) + 62]. Blood flow restriction training will be performed at 30-40% of the arterial occlusion pressure for the upper limb and total duration of 15 minutes. The amount of occlusion pressure will be re-evaluated every two weeks.

Statistical analyses will perform using SPSS program. Descriptive statistics will be presented with means and standard deviations for numerical data and with numbers (n) and percentages (%) for non-numerical data. The suitability of the data obtained from the patients to the normal distribution will be evaluated by the Kolmogorov-Smirnov test. In the case of the normal distribution of data, comparisons between groups will be tested using repeated-measures analysis of variance (two-way ANOVA). When the parametric test conditions are not met, before-after differences within the group will be calculated and the Mann Whitney U test will be used in the analysis of the differences between the groups. Wilcoxon test will be used in intra-group comparisons before and after treatment. In all analyzes, the significance value will be determined as p=0.05.

Inclusion Criteria:

• Volunteer to participate in the study
• Being 18-45 years
• Unilateral rotator cuff related shoulder pain
• No symptoms in the contralateral shoulder

Exclusion Criteria:

• Diagnosis of hypertension, cardiovascular diseases, peripheral vascular diseases, deep vein thrombosis history, neurological diseases, systemic inflammation, obesity, diabetes
• Subject has cancer
• Pregnancy status
• Cervical symptoms
• Shoulder range of motion limitation
• Injection to the shoulder joint in the last 6 months
• Individuals who do not agree to participate in the study

Patients with rotator cuff related shoulder pain (tendinopathy findings in ultrasonographic evaluation).