Intra-subject repeatability of the three dimensional angular kinematics within the lumbo–pelvic–hip complex during running

The intra-subject repeatability of measuring the three dimensional (3D) angular kinematics of the lumbo–pelvic–hip complex during running was evaluated. Spatio-temporal parameters were found to be repeatable. All angular kinematic parameters displayed high within-day repeatability despite numerous potential sources of variability in the data. Most angular kinematic parameters also displayed high between-day and overall repeatability, except for trunk flexion-extension, lumbar spine flexion-extension, pelvic anterior–posterior tilt, hip axial rotation and thigh axial rotation. These angular parameters were highly susceptible to marker reapplication errors that produced static daily offsets in the data. Overall, the results of this study suggest that the 3D angular kinematic patterns of the lumbo–pelvic–hip complex during running can be measured with sufficient repeatability to justify the implementation of the method as an evaluation tool in future investigations. However, caution must be exerted when interpreting the absolute magnitudes of trunk flexion-extension, lumbar spine flexion-extension, pelvic anterior–posterior tilt, hip axial rotation and thigh axial rotation, given the poor level of repeatability found for these measures.