Shoulder Injuries and Sport-Specific Shoulder Adaptations in Judo Athletes: A Systematic Review

Background/Objectives: The shoulder girdle is a frequent injury location in judo, and sport-specific shoulder-complex adaptations have been described in overhead sports, but these areas have not been synthesised for judo athletes. We synthesised evidence on (Q1) the frequency, anatomical profile, type and mechanism of shoulder girdle injuries and (Q2) the structural and functional characteristics of the shoulder complex in judokas. Methods: PubMed, Web of Science, Scopus and EBSCOhost were searched up to 7 August 2026. Two reviewers independently selected studies and extracted data. Risk of bias was assessed with JBI tools and ROBINS-I, and certainty of evidence with GRADE. Because injury definitions and measurement protocols were heterogeneous, a narrative synthesis (SWiM) with stratified descriptive analyses replaced the planned meta-analysis. Results: Twenty-three reports (22 studies) were included. Across 11 studies, shoulder girdle injuries accounted for 10.2-25.5% of recorded injuries (median 17.1%); this proportion depended on injury definition, exposure context and ascertainment and does not estimate prevalence. The shoulder ranked first or second among anatomical locations in 9 of 11 studies. Acromioclavicular joint injuries and glenohumeral dislocation/instability predominated. In one controlled study, judokas had higher internal rotator strength and a lower external-to-internal rotation (ER:IR) strength ratio than non-athletes; inter-limb asymmetry was inconsistent, and glenohumeral internal rotation deficit was not studied. Certainty of evidence was very low for all outcomes. Conclusions: The shoulder girdle is consistently among the most frequently injured locations in judo, whereas evidence for a judo-specific shoulder adaptation profile is sparse, heterogeneous and of very low certainty.