Kinematic analysis of symmetric axial trunk rotation on dominant hip.

Axial rotation of the trunk has been reported as a significant risk of low back dysfunction. However, a lack of biomechanical investigation exists that explains how twisting is accomplished with simultaneous asymmetric handling between the hip joints and lumbar spine. We used a three-dimensional motion analysis to measure movements of the bilateral hips and lumbar spine. Forty-four persons participated in the study, and the results indicated that spinal range of motion (ROM) was significantly different based on dominance (F = 198.83, p = 0.001), region x dominance (F = 14.21, p = 0.001), and dominance x dimension (F = 141.08, p = 0.001). We also found a three-way interaction between region x dominance x dimension (F = 26.30, p = 0.001). These results indicated that the motion of the transverse and sagittal planes significantly increased when the participants attempted to rotate their hips, especially on the nondominant side. Decreased axial trunk ROM on the side of dominance might stiffen passive structures of the hip joints. The functions of the hip joints and lumbar spine might be altered three dimensionally based on the side of dominance.