The Comparison for Serratus Anterior Muscle Activity during Protraction in Open Chain and Closed Chain Exercises in Healthy Adults

Abstract

Background In shoulder dysfunction, shoulder pain, and glenohumeral joint impingement, it is necessary to activate the serratus anterior muscle. Purpose This study aimed to compare serratus anterior muscle activity during protraction in open chain and close chain exercises in order to determine the posture that is best at selectively activating the serratus anterior muscle. Study design One group, two condition design. Methods Thirteen healthy university students participated in this study. The muscle activities of the serratus anterior, the upper trapezius, and the pectoralis major during protraction of scapula were recorded using a wireless surface electromyography system. The subjects performed protraction of scapula on both open chain exercise in supine posture and closed chain exercise in quadruped posture. To evaluate the selective activation of the serratus anterior muscle, the ratio of the serratus anterior activation versus the upper trapezius activation and the ratio of the serratus anterior activation versus the pectoralis major activation were calculated. Results The muscle activity of serratus anterior was significantly higher and pectoralis major was significantly lower the open chain exercise rather than the closed chain exercise. The muscle activity of upper trapezius was not significantly difference between two exercises. Also, each ratio of serratus anterior against other muscles was significantly high in open chain exercise. Conclusions This study’s findings suggest that the open chain exercise in supine posture is better than the closed chain exercise in quadruped posture for selective activation of the serratus anterior muscle.