EFFECTS OF CONVENTIONAL SHOULDER VERSUS TRUNK–SHOULDER CHAIN EXERCISES ON MUSCLE ACTIVATION ONSET AND ISOKINETIC TORQUE IN BASEBALL PITCHERS WITH SUBACROMIAL PAIN SYNDROME: A SINGLE-BLINDED RANDOMIZED CONTROLLED TRIAL

Subacromial pain syndrome (SAPS) in overhead athletes is associated with altered trunk–shoulder neuromuscular coordination and external rotator muscle weakness. This randomized controlled trial aimed to compare the effects of conventional shoulder exercises (CSE) and trunk–shoulder chain exercises (TCE) on clinical and biomechanical outcomes in 40 collegiate baseball pitchers with SAPS. The participants completed supervised sessions three times a week for six weeks. Outcome measures included the numeric pain rating scale (NPRS), shoulder pain and disability index (SPADI), electromyographic (EMG) onset timing, and isokinetic peak torque for external and internal rotation (ER/IR). The TCE group demonstrated significantly greater improvements in NPRS and SPADI scores ([Formula: see text]), earlier activation of core and scapular stabilizers (e.g., internal oblique/transversus abdominis (IO/TrA) and serratus anterior (SA)), delayed activation of shoulder prime movers (e.g., pectoralis major (PM) and anterior deltoid (AD)), and higher concentric (CON) and eccentric (ECC) torques ([Formula: see text]) than the CSE group. These findings suggest that restoring the proximal-to-distal kinetic chain using TCE is more effective than conventional shoulder training in alleviating pain, enhancing function, neuromuscular control, and augmenting strength. This study supports the clinical value of kinetic chain-based rehabilitation in overhead athletes with SAPS.