Minimum principles for muscle-coordination evaluated by the directional preference of muscle activation during multijoint-arm force regulation tasks

摘要

To investigate principles of muscle regulation, we measured variations of muscle activities during multijoint static force regulation tasks in a horizontal plane. The results show that activities of monoarticular muscles at the shoulder and elbow joints strongly covaried with the corresponding joint torque respectively, and that the activities of biarticular muscles were covaried to some extent with the elbow joint torque. In the light of muscle directional preferences, several minimum principles have been considered to describe the variation of muscle activities. The characteristics of muscle directional preferences have been nicely reproduced by minimizing sum of muscle stress squared, suggesting that this minimum principle is a dominant constraint of muscle coordination by the central nervous system.