Muscle Activation of Serratus Anterior during Self-Resisted Scapular Protraction with Forward Flexion on Unstable Surface in Sitting Position

Abstract

Normal muscle activity of the serratus anterior (SA) is essential in the alignment of the scapula and its function of motion. SA muscle weakness leads to changes in the movement of the scapula, resulting in shoulder pain and delayed movement, being one of the causes of scapular dyskinesis. Therefore, scapular protraction exercises have been suggested for weakness of SA, as a way to strengthen it. Previous studies have mentioned that scapular protraction exercises are effective in increasing SA muscle activity. In particular, push-up plus exercise along with scapular protraction exercise was found to be more effective than the conventional push-up because it increases SA activity while minimizing the activity of the upper trapezius (UT). Previous studies suggested that 120° forward flexion is combined with scapula protraction, scapular upward rotation and posterior tipping contributing to increased SA muscle activity. Moseley et al. stated that 95% of the maximum muscle strength of SA occurs when the angle of shoulder flexion is between 120° and 150°. Exercises including forward flexion, Muscle Activation of Serratus Anterior during Self-Resisted Scapular Protraction with Forward Flexion on Unstable Surface in Sitting Position