Proximal Effects of Blood Flow Restriction on Shoulder Muscle Function and Discomfort During Low-Intensity Exercise

This study aimed to examine the proximal effects of blood flow restriction (BFR) training on shoulder muscle function and subjective discomfort during low-intensity external rotation exercise. Twenty-four healthy adults were randomly assigned to a BFR group or a control group and performed shoulder stabilization exercises with or without BFR. Outcome measures included shoulder external rotation range of motion, maximal isometric strength, muscle endurance, electromyographic activity of the rotator cuff muscles, and perceived discomfort. Both groups demonstrated significant within-group improvements in all outcomes except posterior deltoid and supraspinatus activity (p < 0.05). Between-group comparisons showed significantly greater gains in maximal strength and infraspinatus and teres minor activation in the BFR group than in the control group (p < 0.05), while discomfort and fatigue scores were also higher in the BFR group (p < 0.05). These findings suggest that BFR applied at the proximal upper arm can enhance the strength and activation of key rotator cuff muscles even when cuff placement near the shoulder is limited by anatomy. Proximal BFR may serve as an effective intervention for improving shoulder function when high-intensity exercise is contraindicated, although strategies to minimize discomfort are needed to improve clinical feasibility.