Neuromuscular Adaptations of the Rotator Cuff and Scapular Stabilizers Following TheraBand-Based Throwing Training in Symptomatic Volleyball Players with Shoulder Internal Rotation Deficit: A Randomized Controlled Trial

Abstract Background: Glenohumeral Internal Rotation Deficit (GIRD) rehabilitation literature lacks comprehensive neuromuscular analysis explaining motor control mechanisms underlying elastic resistance training effectiveness. Current evidence emphasizes range of motion and pain outcomes without addressing rotator cuff and scapular stabilizer activation patterns or co-contraction dynamics essential to shoulder stability. Objective: This randomized controlled trial investigated neuromuscular adaptations in rotator cuff and scapular stabilizer musculature following 12-week TheraBand-based throwing training in symptomatic collegiate volleyball players with GIRD. Methods: Sixty-four male collegiate volleyball players (age 20.4±1.9 years) with documented GIRD (≥10°) and scapular dyskinesis were randomized to intervention (n=32) or control (n=32) groups. The intervention consisted of progressive 12-week TheraBand-based throwing exercises emphasizing external rotator strengthening and scapular stabilization. Primary outcome measures included surface electromyography (%MVIC) of infraspinatus, subscapularis, lower trapezius, and serratus anterior muscles during standardized functional tasks. Secondary measures encompassed muscle co-contraction ratios, calculated shoulder joint stability indices, pain intensity (VAS), disability (DASH), quality of life (WORC), and return-to-play readiness. Results: Intervention group participants demonstrated remarkable neuromuscular adaptations. Infraspinatus EMG activation increased 117% from baseline 22.3%±8.4% MVIC to post-intervention 48.6%±9.2% MVIC (p