엎드린 자세에서 어깨 폄 운동 시 목과 어깨 돌림 위치에 따른 등세모근 근활성도 비교

Abstract

Background: Prone shoulder extension exercises are commonly used to strengthen the scapular stabilizers, particularly the trapezius muscle. While previous studies have examined the effects of shoulder abduction angle and rotation alone, the combined influence of cervical and glenohumeral rotations on activation of the upper (UT), middle (MT), and lower trapezius (LT) remains unclear. Clarifying these interactions is essential for optimizing rehabilitation programs that target specific trapezius subregions through muscle length–tension modulation. Methods: Twelve healthy male adults performed nine variations of prone shoulder extension combining three neck positions with three shoulder rotations. Surface electromyography recorded trapezius activity, normalized to %MVIC. Each condition was held briefly and repeated with adequate rest to minimize fatigue. Repeated‑measures ANOVA and Bonferroni post‑hoc tests were used to compare activation across conditions (α = .05). Results: Upper trapezius activation was significantly higher in the neck contralateral rotation with shoulder external rotation position compared to the neck ipsilateral rotation with shoulder internal rotation position (p<.05). No significant differences were observed in middle trapezius activation across all exercise variations (p>.05). Lower trapezius activation was significantly higher in the neck neutral with shoulder neutral position compared to the neck ipsilateral rotation with shoulder internal rotation position (p<.05). Conclusion: Cervical and shoulder rotations distinctly modulate UT activation via alterations in muscle length, whereas MT remains stable and LT shows selective sensitivity under fully neutral positioning. These findings highlight the importance of considering coupled neck–shoulder kinematics to selectively target trapezius subregions in rehabilitation, and suggest that incorporating trunk rotation warrants further investigation for MT and LT modulation.