Trapezius Muscle Activation During Bilateral Scapular Retraction and Shoulder External Rotation Under Kinetic Chain and Unstable Surface Conditions

This study aims to investigate the effects of performing the Bilateral Scapular Retraction with Shoulder External Rotation (BSR-SER) exercise under kinetic chain involvement and unstable surface conditions on trapezius muscle activation. Surface electromyography (EMG) will be used to assess the activity levels of the upper, middle, and lower trapezius muscles. The goal is to determine whether integrating kinetic chain elements and instability can optimize muscle activation patterns in healthy individuals during a commonly used scapular rehabilitation exercise.