Development of a measurement and real-time display system for kinematics and muscle synergy of gait

Recently, muscle synergy has drawn increasing attention to understand human movement. In this study, we present a system that is able to display concurrently both the kinematics (stick pictures) and muscle synergy of gait. Our system has been developed at the Rehabilitation Center of the University of Tokyo Hospital comprising a kinematics measurement device and muscle synergy measurement device for gait. The kinematics is measured with a three-dimensional motion analysis system. Infrared reflective markers are attached according to the Plug-in Gait marker set. The trajectory of the reflective markers can be displayed in real time during measurements. The muscle synergy is calculated from myoelectric activity obtained from surface electromyography. Surface electrodes are attached to 16 lower-limb muscles. The calculation of the muscle synergy from the myoelectric activity is conducted with originally developed software that uses non-negative matrix factorization. The calculation results of the muscle synergy can be displayed in almost real time. A common trigger signal is send both to the motion analysis system and the synergy calculating software for synchronization. Using this as a visual feedback system, patients can attempt to correct their gait abnormality. Thus, this system is not only a measurement device but may also be applied as a therapeutic device.