Changes in neck and upper trunk muscle activities according to the angle of movement of the neck in subjects with forward head posture.

[Purpose] This study investigated changes in neck and upper trunk muscle activities according to the angle of movement of the neck in subjects with Forward Head Posture. [Subjects and Methods] Twenty subjects with forward head postures were recruited. The activities of the sternocleidomastoid muscle, splenius capitis and splenius cervicis muscles, upper trapezius muscle, and middle trapezius muscle during flexion and extension were assessed. [Results] The activity of the sternocleidomastoid muscle showed significant differences between the 30° flexed position and the full range of motion position, and between the neutral position and the full ROM position. The activity of the middle trapezius muscle showed a significant reduction in the 30° extended position and the full ROM position as compared to the neutral position. [Conclusion] In the full flexed position, sternocleidomastoid muscle activity increased significantly, and during extension position, the middle trapezius muscle reduced its activities.