Investigation of the effect of blood flow restriction training onshoulder muscle thickness and symptoms in rotator cuff tendinopathy

The aim of this study was to investigate the effects of blood flow restriction training (BFRT) on shoulder muscle thickness, muscle strength, and shoulder symptoms in rotator cuff tendinopathy. Thirty-two patients aged between 18- 45 years with diagnosed rotator cuff tendinopathy due to unilateral shoulder pain were included in the study. Patients were randomly allocated into two groups: the BFRT group (age: 31.5±5.1 years, height: 171.7±8.7 cm, body weight: 71.8±11.3 kg) and the control group (age: 34.9±5.4 years, height: 172.1±8.6 cm, body weight: 72.9±13.6 kg). A progressive rehabilitation program was applied to both groups twice a week for eight weeks. Patients in the BFRT group performed rehabilitation exercises with a 5 cmwide pneumatic cuff placed at the most proximal portion of the painful shoulder, while patients in the control group performed the same exercise protocol without the cuff. The exercises in both groups were performed at low intensity (30% of 1 repetition maximum), 4 sets, with a total of 75 repetitions (30/15/15/15). Before and after the rehabilitation, the thickness of the supraspinatus, infraspinatus, deltoid, biceps brachii, and scapula-retractor muscles, as well as the acromiohumeral (AH) distance, were measured using ultrasonography. Shoulder internal and external rotator muscle strengths were measured using an isokinetic dynamometer at angular velocities of 60º/s and 180º/s. Additionally, shoulder pain was assessed using a visual analog scale, and shoulder function was evaluated using the Shoulder Pain and Disability Index (SPADI). The BFRT group had a greater increase in biceps brachii muscle thickness (p<0.001) and higher shoulder internal rotation muscle strength at 60º/s (p=0.02) compared to the control group after the rehabilitation. There were no significant differences between the groups in terms of other shoulder muscle thicknesses, AH distance, and rotator muscle strength (p>0.05). Both groups showed a significant increase in the supraspinatus (p=0.003), infraspinatus (p=0.001), and scapula-retractor (p=0.02) muscle thicknesses, and all shoulder rotator muscle strengths over time (p<0.05). The shoulder function measured by the SPADI score after the rehabilitation was better in the BFRT group (p=0.04). However, both groups showed a reduction in pain and improvement in shoulder function over time (p<0.05). The results indicated that BFRT applied in rotator cuff tendinopathy had positive effects on both proximal (shoulder internal rotation muscle strength) and distal (biceps brachii muscle thickness) sites of the occlusion. BFRT can be utilized as an alternative to traditional rehabilitation protocols in shoulder rehabilitation.