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

## TL;DR

Blood flow restriction training on the upper arm improves shoulder muscle strength and activation during low-intensity exercise, but causes more discomfort.

## Contribution

Demonstrates that proximal BFR can enhance rotator cuff muscle function without placing the cuff near the shoulder.

## Key findings

- BFR group showed greater gains in maximal strength and infraspinatus and teres minor activation compared to the control group.
- Both groups improved in most outcomes, but BFR caused higher discomfort and fatigue scores.
- Proximal BFR can be effective for shoulder function when high-intensity exercise is not possible.

## Abstract

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.