Effect of various hand position widths on scapular stabilizing muscles during the push-up plus exercise in healthy people

[Purpose] The purpose of this study was to determine the effect of various hand position widths during the push-up plus (PUP) exercise on the activity of the scapular stabilizing muscles and other upper-extremity muscles involved in the exercise. [Subjects and Methods] Nine healthy men participated in our study. The PUP exercise was performed on a stable surface in seven different hand positions, namely shoulder width (SW), and narrower SW (NSW) and wider SW (WSW) at 10%, 20%, and 30%. Surface electromyography was used to measure the muscle activities and muscle ratio of the upper trapezius (UT), middle trapezius, lower trapezius (LT), serratus anterior (SA), pectoralis major, deltoid anterior, latissimus dorsi (LD), and triceps muscles. [Results] The SA and LD muscle activities significantly decreased in the 30% NSW and 20% WSW hand positions, respectively. The UT/LT muscle ratio significantly increased in the 30% WSW hand position. [Conclusion] The results of this study suggest that during the PUP exercise, the SW hand position should be used. In the 30% NSW hand position, the SA muscle activity decreased, and the UT/ LT ratio increased in the 30% WSW hand position.