Detecting spinal posture change in sitting positions with tri-axial accelerometers.

A method of using three tri-axial accelerometers for monitoring postural changes in sitting was introduced. Subjects were requested to perform forward trunk flexion and lateral bending. A motion analysis system and a three-dimensional rotation alignment device were used to verify the measurements of the accelerometers. The precision and reliability of the accelerometers for measuring static calibration was demonstrated as < or =1 degrees for the RMS error and 1.000 for ICC(3,1). For measurements of sitting posture, the averaged RMS difference between the measurements of the accelerometers and the motion analysis system were < or =5 degrees for all sitting postures on the coronal and sagittal planes. The results of this study demonstrated that tri-axial accelerometers could be used for tracking spinal postural changes on the sagittal and coronal planes in the sitting positions.