3-D Inverse Dynamics Analysis of the Effect of Maximum Muscle Force Capacities on a Musculoskeletal System

It is known that muscle strength of human body can alter or deteriorate as aging. In thisstudy, we present an inverse dynamics simulation to investigate the effect of muscle strength onperforming the daily activities. A 3D musculoskeletal model developed in this study includes severalsegments of whole body, long and short muscles, ligaments and disc stiffness. Five daily activitiessuch as standing, flexion, finger tip to floor, standing lift close and lifting flexed were simulated withvarying the maximum muscle force capacities (MFC) of each muscle fascicles from 30 to 90 N/cm2with an increment of 30 N/cm2. In the result, no solution can be obtained for finger tip to floor andlifting flexed with 30 N/cm2. Even though the solution was available for standing lift close activity incase of 30 N/cm² capacity, many of muscle fascicles hit the upper bound of muscle strength whichmeans that it is not physiologically possible to perform the acvities in reality. For lifing flexed, eventhe case of 60 N/cm2 capaciy, represents the moderate healthy people, was not able to find thesolutions, showing that 18 muscles among 258 muscle fascicles reached 100% of muscle capacity. Theestimated results imply that people who have low muscle strength such as elders or rehabilitationpatients were required higher muscle work to perform and maintain the same daily activities thanhealthy one. KCI Citation Count: 3