Relative Electromyogram Integral Value Changes in the Vertebral, Iliac and Costal Fibers of the Latissimus Dorsi Elicited by Different Joint Movements

Abstract

[Purpose] In this study, we compared the relative electromyography integral values associated with changes in the motion of the latissimus dorsi muscle vertebral fibers, iliac fibers, and costal fibers. [Participants and Methods] Ten healthy men were the subjects. They performed tasks of maintaining shoulder joint extension, shoulder joint rotation, subscapular girdle, and thoracolumbar lateral flexion. Electromyography (EMG) was used to measure the muscle activities in each limb position, and the relative EMG integral values were examined. [Results] Vertebral fiber activities were increased in shoulder joint extension compared to the other tasks. Iliac fiber activities were increased in the subscapular girdle task compared to the shoulder joint extension and internal rotation tasks. An increase was also observed in the thoracolumbar lateral flexion task compared to the shoulder articular rotation task. The rib fiber activities were increased in the subscapular girdle task compared to the other tasks. [Conclusion] The latissimus dorsi muscle showed different activities among its three fibers.