Effect of isometric horizontal abduction on pectoralis major and serratus anterior EMG activity during serratus anterior activation exercises in subjects with scapular winging

Abstract

The aim of this study was to determine the effect of isometric horizontal abduction (IHA) using Thera-Band during three serratus anterior (SA) activation exercises (forward flexion, scaption, and wall push-up plus) in subjects with scapular winging by investigating the EMG amplitude of the pectoralis major (PM) and SA and the PM/SA activity ratio. Twenty-four males with scapular winging participated in this study. Scapular winging was confirmed by measuring the distance between the thoracic wall and the inferior angle of the scapula using a scapulometer. A distance equal to or greater than 2㎝ was defined as scapular winging. The subjects performed the forward flexion, scaption, and wall push-up plus with and without IHA using Thera-Band. Surface EMG was used to collect the electromyographic (EMG) data of the PM and SA during the SA activation exercises. Two-way repeated analyses of variance with two within-subject factors (IHA condition and exercise type) were used to determine the statistical significance of PM and SA EMG activity and the PM/SA EMG activity ratio. PM EMG activity was significantly lower during forward flexion and wall push-up plus with IHA, and SA EMG activity was significantly greater with IHA. Additionally, the PM/SA activity ratio was significantly lower during the forward flexion and wall push-up plus with IHA. The results of this study suggest that IHA using Thera-Band can be used as an effective method to facilitate selective SA strengthening and the reduction of excessive PM activity during SA activation exercises.