Contralateral Resistance Training During Immobilization in Patients With Acromioclavicular Joint Injury

This randomized controlled trial aims to compare the effects of contralateral eccentric and concentric resistance training performed during the immobilization period following acromioclavicular joint injury. Immobilization is commonly prescribed after injury but may lead to reductions in muscle mass, neuromuscular function, force production, and upper-limb functionality. Contralateral resistance training, also known as cross-education training, involves exercising the non-injured limb to induce beneficial adaptations in the immobilized limb through neural mechanisms. While both eccentric and concentric exercise may produce contralateral effects, their relative effectiveness in a clinical population remains unclear. Participants with acute acromioclavicular joint injury requiring sling immobilization will be randomly assigned to either a contralateral eccentric training group or a contralateral concentric training group. During immobilization, participants will perform supervised resistance training with the non-injured upper limb. Following immobilization, all participants will receive the same standardized rehabilitation program. Neuromuscular function, muscle morphology, force production, upper-limb function, and quality of life will be assessed before immobilization, after immobilization, and following rehabilitation. The findings may contribute to the development of more effective rehabilitation strategies for patients recovering from upper-limb injuries requiring temporary immobilization.

Inclusion Criteria: * Men and women aged 18 to 36 years. * Diagnosis of acute acromioclavicular joint injury confirmed by an orthopedic surgeon. * Physician-prescribed upper-limb immobilization using a sling for approximately 2 to 4 weeks, with or without surgical repair. * Ability to understand study procedures and provide written informed consent. * Medical clearance to participate in the rehabilitation and resistance training program. Exclusion Criteria: * Previous surgery or severe musculoskeletal injury affecting either upper limb within the previous 12 months. * Neurological disorders affecting motor function or neuromuscular performance. * Contraindications to transcranial magnetic stimulation according to established safety guidelines. * Current participation in another clinical trial or structured upper-limb rehabilitation program. * Cognitive impairment or inability to comply with study procedures. * Pregnancy. * Any medical condition that, in the opinion of the investigators, may compromise participant safety or study participation.