Effects of Different Directions of Arm Movement on EMG Discharge Patterns of Deltoid Muscle
shoulder abduction angle
shoulder flexion movement
The present study was undertaken to investigate the direction-sensitivity of the arm control system using an appropriately modified version of the shoulder flexion movement. The results indicated that small initial shoulder abduction angles were associated with longer agonist (anterior deltoid muscle) EMG durations. Moreover, as initial shoulder abduction angles became smaller, EMG onsets of the antagonist (posterior deltoid muscle) occurred nearer to those of the agonist. Modulations of duration of the agonist EMG burst can be explained by changes in movement amplitudes. With regard to modification of time difference between agonist and antagonist, the interpretation concerns the changing role of the antagonist to a synergist dependent on decreased initial shoulder abduction angles. Based on the present findings, it is suggested that shoulder abduction angles are an important determinant of agonist-antagonist muscle activity of deltoid during flexion of the shoulder.
広島文教女子大学 : 広島文教女子大学短期大学部