Objective : The aim of this study was to analyze the three-dimentional Kinematics of the trunk between skilled and novice boxers in the boxing defense (Swaying thechnique). Methods : Eight university boxers (BOX) and seven university students without the boxing experience (CON) were subjects. The angle of thoracolumbar vertebrae was measured by the three-dimensional magnetic position sensor. The trunk angle, the hip joint angle, and the knee joint angle were measured with three-dimensional motion analysis system. Results : As a result of the three-dimensional magnetic position sensor, there was not the difference to thoracolumbar vertebrae extension angle, and the thoracolumbar vertebrae extension angle was about 23 degrees. From three-dimensional motion analysis, CON suited the tendency for the knee joint angle of non dominant leg to be larger than BOX (p＝0.06). Discussion : The possibility that a lumbar extension contributed to the low back pain onset of the boxer was suggested
