Inertial measurement units furnish accurate trunk trajectory reconstruction of the sit-to-stand manoeuvre in healthy subjects.

A simple inertial measurement unit (IMU) incorporating rate gyroscopes and accelerometers has been tested to investigate the trunk kinematics during the sit-to-stand. It was affixed at trunk L5 level and used for sit-to-stand position and orientation reconstruction. The method was validated with standard optoelectronic equipment and results were also compared to the ones obtained by means of a Fast Video Camera. Comparative results showed for the IMU better performance than the system based on the Fast Video Camera. During the rising the mean pitch error was always lower than 5.2 x 10(-1) degrees and the mean Euclidean error lower than 5.9 x 10(-3) m in the sagittal plane.