Effects of Changing the Resistance Direction Using an Elastic Tubing Band on Abdominal Muscle Activities during Isometric Upper Limb Exercises

[Purpose] We investigated the effects of changing the resistance direction using an elastic tubing band on abdominal muscle activities during isometric upper limb exercises in a seated position. [Subjects] Twenty able-bodied volunteers (10 males, 10 females) were recruited for the study. [Methods] All subjects performed isometric upper limb exercises with an elastic tubing band involving three different shoulder movements (extension, flexion, and horizontal abduction). Surface electromyography (EMG) signals were recorded from the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) bilaterally during isometric upper limb exercises. [Results] There were significant differences in EMG activity of the bilateral RA during shoulder extension, shoulder horizontal abduction, and shoulder flexion. The EMG activities of the bilateral EO and IO were significantly higher in shoulder extension and horizontal abduction than in shoulder flexion when the subjects performed the arm exercise in the seated position. There was no significant difference between shoulder extension and horizontal abduction. [Conclusions] We suggest that upper limb extension and horizontal abduction using an elastic tubing band could be effective at improving abdominal muscle activities without trunk movement during isometric upper limb exercises.