Abstract
[Purpose] The purpose of this study was to investigate the differential effects of fixation of the thoracolumbar junction on the activity of the thoracic and lumbar muscle groups with and without the abdominal drawing-in maneuver (ADIM). [Subjects and Methods] The participants were 40 healthy adults. During trunk extension, thoracic and lumbar muscle activities were assessed using surface electromyography when fixing the pelvic and popliteal areas and the thoracolumbar junction, with and without the ADIM. [Results] The activity of the thoracic extensors at the T9 level applying thoracolumbar fixation with ADIM was significantly higher than with only pelvic fixation or pelvic fixation with ADIM during prone trunk extension. However, the activity of the lumbar extensors at the L3 level with pelvic fixation alone, without ADIM, was significantly higher than pelvic fixation with ADIM or additional thoracolumbar fixation with ADIM during prone trunk extension [Conclusion] This study demonstrated that fixation of the thoracolumbar junction with ADIM during trunk extension was more effective at eliciting thoracic extensor and minimising lumbar extensor activity than other conventional fixation methods.