Kinetic and EMG Analyses of Shoulder Muscles during Closed Chain Activities on Stable and Unstable Surface

• Main Authors: Shih-Bin Chen, 陳仕彬
• Other Authors: Ar-Tyan Hsu
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/85509536875125349372

碩士 === 國立成功大學 === 物理治療研究所 === 95 === Previous studies on shoulder muscle strengthening and rehabilitation emphasized the use of open kinetic chain exercises. However, there is limited information on closed kinetic chain exercises. The purpose of this study was to analyze and compare kinetics and electromyographic (EMG) data during closed kinetic chain exercises, in order to explore the kinetic characteristic and EMG data of the shoulder weight-bearing exercise. Twenty male subjects participated in the study. They performed different shoulder weight-bearing exercises by controlling several factors, including foam, posture, support, and position. Each subject performed exercises directly bearing on the force plate or foam, in hand-sand-knees or hands-and-feet postures combined four point, three point, diagonal, or unilateral support. Then each subject was asked to shift his body forward, backward, leftward, and rightward to different positions. Outcome measures were the angle of the shoulder joint, EMG activities of shoulder muscles, shoulder joint reaction force, and torque. In our study, the foam cause a significant increase of shoulder joint reaction force in anterior and lateral direction but decrease in inferior direction (p value < 0.05), and didn’t have influence for shoulder torque (p value > 0.05). The foam resulted in the EMG slightly increased, but there was on significant difference (p value > 0.05). For all outcome measures, the hands-and-feet posture was significant higher than the hands-and-knees posture (p value < 0.05). The diagonal support resulted in the highest shoulder joint reaction force in anterior and lateral direction, and the three point support resulted in the highest shoulder joint reaction force in inferior direction (p value < 0.05). The shoulder flexor and scapular upward rotator had the highest EMG firing in the diagonal support (p value < 0.05), but other shoulder muscles had the highest EMG firing in the unilateral support (p value < 0.05). However, the hands-and-feet posture could enhance the difference between different supporting methods. The extension and horizontal adduction positions could in highest EMG activities and shoulder reaction force in inferior direction. The posture and support were the primary factors to influence the shoulder joint reaction force, torque, and EMG activities. The hands-and-feet posture combined diagonal support or unilateral for different muscles resulted in the highest muscle loading, and shoulder loading. The information about muscle activities and kinetic data during shoulder weight-bearing exercises was useful for physical therapists to combine open kinetic chain exercises to design appropriate exercises programs for patients.