The Effects of Changes in Hand Position on the Electromyographic Activities of the Shoulder Stabilizer Muscles during Push-up Plus Exercises on Unstable Surfaces

Abstract

[Purpose] The purpose of the present study was to examine the effects of changes in hand position on the electromyographic activities of the shoulder stabilizer muscles during push-up plus exercises (PUPE) on unstable surfaces. [Subjects] The subjects of the present study were normal adults in their 20s (n=15). PUPEs were performed with the hands in the neutral positions (NP), internal rotation positions (IRP), and external rotation positions (ERP) using a sling device for the unstable surface. [Methods] We measured the electromyographic activities of the wrist flexor (WF), the wrist extensor (WE), the biceps brachii (BB), the triceps brachii (TB), the upper trapezius (UT), the lower trapezius (LT), the serratus anterior (SA), and the pectoralis major (PM). The muscle activites were compared and analyzed using electromyography. [Results] When hand position changed, WF activity in NP, and SA activity in ERP, were significantly different from their respective activities in the other positions. [Conclusion] To selectively enhance the electromyographic activity of the SA during PUPE using a sling device as an unstable surface, we consider performance of PUPE in ERP is an effective intervention.