Effect of shoulder flexion angle and exercise resistance on the serratus anterior muscle activity during dynamic hug exercise

[Purpose] The primary aim of this study was to determine the effect of shoulder flexion angle and exercise resistance on the serratus anterior muscle during dynamic hug exercise. [Subjects] Ten men aged 22-32 years were recruited. [Methods] The subjects performed dynamic hug exercise at different shoulder flexion angles and under resistance weight conditions. Serratus anterior muscle activities were measured by using the surface electromyographic system during the dynamic hug exercises. After performing the exercise, each subject described the exercise intensity by using the Borg rating of perceived exertion (RPE) scale. [Results] The normalized serratus anterior muscle activity increased significantly in the order of Conditions 1 and 4 < Condition 3 < Condition 2. The Borg RPE scale increased significantly in the order of Condition 1 < Condition 2 < Condition 3 < Condition 4. [Conclusion] The results suggest that dynamic hug exercise with the use of a multi-air-cushion biofeedback device is an effective scapular stability exercise.