Muscle Synergy Analysis Between Young and Elderly People in Standing-Up Motion

Standing up is fundamental to daily activities of the elderly. It is necessary both to enhance muscle strength and to strengthen muscle coordination for improvement of their motor function. In this paper, we extract important data related to muscle coordination, called synergy, to perform standing motion by young and elderly participants. The contribution of muscle synergy to body kinematics is calculated through neural networks that estimate joint torque and body kinematics. To explain deficient motor function in elderly persons, extracted synergy is classified into 4 clusters based on how synergy contribute to body kinematics. Cluster analysis explains that elderly participants have weaker synergy than young persons in bending their backs to generate momentum. Compared to younger persons, older persons require additional muscle coordination to stabilize posture after standing-up in order to avoid falling.