Electromyographic analysis of shoulder muscles during press-up variations and progressions

Abstract

Due to the versatility of the press-up it is a popular upper extremity strengthening and rehabilitation exercise. Press-up programmes are often progressed by increasing weight-bearing load and using unstable bases of support. Despite the popularity of the press-up research examining press-up variations is limited. The aim of the study was to examine the influence of common press-up exercises on serratus anterior, infraspinatus, anterior deltoid, pectoralis major and latissimus dorsi muscles overall EMG activity. Twenty-one healthy individuals participated in this study. Surface electrodes were placed on pectoralis major, anterior deltoid, infraspinatus, serratus anterior and latissimus dorsi muscles. Participants were tested under 7 static press-up conditions that theoretically progressively increase weight-bearing load and proprioceptive challenge while surface electromyographic activity was recorded. There was a high correlation between increased weight-bearing load and increased EMG activity for all muscles in stable base conditions. The introduction of the unstable base conditions resulted in an activation decline in all muscles. Within the two-armed press-up the Swiss ball resulted in decreased activation in all muscles except pectoralis major. Serratus anterior demonstrated the greatest activation as a percentage of maximum isometric contraction across all exercises. The findings of this study indicate that by varying the weight-bearing load and base of support whilst in the press-up position results in significantly different demands on shoulder and scapula muscles.

Keywords: EMG; Load; Shoulder.