Comparison of Muscle Activity of the Erector Spinae according to Thoracic Spine Extension Mobility

Abstract

Mechanical pain disorders of the thoracic spine are commonly associated with impairment of thoracic spine mobility. Impairment of thoracic spine mobility is frequently reported in axial rotation and extension. Thoracic spine extension mobility (TE) is required in the end range of shoulder flexion, and is essential for ideal pattern of trunk extension. Prone trunk extension is performed to check the ideal trunk extension pattern. Park et al. reported that those with a slouched posture had smaller thoracic spine extension and greater lumbar extension during the prone trunk extension compared to those without slouched posture. Also, the muscle activity ratio between the thoracis and lumborum of erector spinae was lower in those with a slouched posture. During prone trunk extension, the thoracic extensor is decreased and the lumbar extensor is excessively activated, which is a factor inducing low back pain. Therefore, muscle activity of thoracic erector spinae was emphasized to manage and prevent low back pain. During the thoracic extension, the thoracic erector spinae such as longissimus thoracis (LT), and iliocostalis lumborum pars thoracis (ICT) are activated. However, since the erector spinae muscle of lumborum such as iliocostalis pars lumborum (ICL) can be used as compensation during trunk Comparison of Muscle Activity of the Erector Spinae according to Thoracic Spine Extension Mobility