Acute Effects of Blood Flow Restriction on Shoulder Pain and Strength in Nonspecific Shoulder Pain-A Randomised Crossover Trial.

Shoulder pain limits function and increases healthcare costs. Resistance training is used, but the most effective approach for pain modulation remains unclear. Blood flow restriction (BFR) training combines low-load exercise with vascular occlusion demonstrating hypoalgesic effects across various disorders. However, evidence for non-specific shoulder pain (NSP) is limited. This study investigated the hypoalgesic effects of a single BFR session in NSP. In this randomized crossover trial, 48 participants with NSP were allocated to a BFR group (n = 24) or a sham-BFR group (n = 24). After a 7-day washout period, participants crossed over to the alternate condition. Each session consisted of low-load biceps curls with either BFR or sham-BFR, followed by a standardized shoulder exercise loading session. Outcomes included pressure pain thresholds (PPT), maximum voluntary isometric contraction (MVIC) of shoulder external rotation, and pain intensity (NPRS) during MVIC and abduction. BFR produced significantly greater increases in MVIC immediately after exercise (EMD = 0.058, p < 0.05) and following standardized shoulder exercise loading session (EMD = 0.042, p < 0.05) compared with sham-BFR. Both interventions reduced pain during external rotation MVIC and shoulder abduction, with larger reductions after BFR. Significant increases in PPT were found at the infraspinatus (EMD = 1.32, p < 0.05) and middle deltoid (EMD = 1.27, p < 0.05) only following BFR. A single low-load BFR session produced immediate, clinically meaningful reductions in pain and improvements in shoulder muscle strength in individuals with NSP, with benefits persisting after a standardized shoulder exercise loading session. Registered in ClinicalTrials.gov (NCT05956288) on 2023-07-21.