척주 기립자세와 굽힌자세에서 어깨관절 외전각도 변화에 따른어깨뼈 주위 근 활성도 분석

Abstract

Altered scapular kinematics in the scapular joint is commonly believed to be a factor contributing totrunk posture. The purpose of this study was to analyze the muscle activity with several changes of theshoulder angle. Tests were performed on 10 male subjects by repeated measures. Each subject was measuredwhile sitting in both erect and slouched trunk positions. In each sitting posture, a three-dimensionalmotion analysis measurement was used to measure thoracic angle and shoulder abduction angle. Measurements were taken with the shoulder abdcution angle at 0°, 30°, 60°, 90°, 120°, and 150°. By usingsurface Electromyography (EMG) electrodes, we recorded the activity of the upper trapezius, middle trapezius,lower trapezius, middle deltoid, and serratus anterior muscle while the subject held a 4 ㎏ weightat each angle. The mean of root mean square (RMS) of EMG activity was calculated. The middle trapezius,lower trapezius, and middle deltoid muscle activity showed significantly higher results but serratusanterior muscle activity showed significantly lower results (p<.05). With the shoulder angle increased, themuscle activity was also significantly increased (p<.05). In conclusion, the thoracic spine posture significantlyaffects the scapular muscle during scapular plane abduction, and the slouched posture is associatedwith increased trapezius muscle activity and with decreased serratus anterior muscle activity.