Relationship between the thoracolumbar flexion angle and pelvic posterior movement during trunk flexion.

[Purpose] The purpose of this study was to investigate the linear relationship between the thoracolumbar flexion angle and hip posterior displacement. [Subjects and Methods] This study was performed on 15 subjects. The subjects performed three trials of a lumbar flexion-extension task. To quantify the statistical linear relationship between the thoracolumbar flexion angle and hip posterior displacement, Spearman's rank correlation coefficient was used. [Results] The thoracolumbar flexion angle was significantly correlated with the degree of hip posterior displacement. [Conclusion] According to the results of this study, movement of the thoracolumbar joint and posterior movement of the pelvis must be considered for accurate analysis of the lumbopelvic rhythm.