Module-E-Joint-Models-_-web-2017-part3.pdf - EMG-driven approach 61 Ways of Dealing with Indeterminacy(Methods to get muscle forces from the NJM 1

Module-E-Joint-Models-_-web-2017-part3.pdf - EMG-driven...

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EMG-driven approach 61
Ways of Dealing with Indeterminacy (Methods to get muscle forces from the NJM) 1. Single Muscle Equivalent (SME) approach 2. Electromyography(EMG)-driven approach 3. Optimization approach 62
Electromyography (EMG) driven approach An approach that incorporates: EMG (activation state) Muscle properties: Stress Physiologic Cross Sectional Area Force Length Relationship Force Velocity Relationship ࠵? ࠵?࠵?࠵?࠵?࠵?࠵? = ࠵?࠵?࠵? ࠵?࠵?࠵? ࠵?࠵?࠵? × ࠵? ࠵?࠵?࠵? × ࠵?࠵?࠵?࠵? × ࠵? ࠵? ࠵? ࠵? × ࠵? ࠵? ࠵? ࠵? + ࠵? ࠵?࠵?࠵?࠵?࠵?࠵?࠵? × ࠵?࠵?࠵?࠵? 63
Anterior Posterior Patellar Tendon Semimembranosus Semitendinosus Biceps Femoris Gastrocnemius ࠵? ࠵?࠵?࠵?࠵?࠵?࠵? = ࠵?࠵?࠵? ࠵?࠵?࠵? ࠵?࠵?࠵? × ࠵? ࠵?࠵?࠵? × ࠵?࠵?࠵?࠵? × ࠵? ࠵? ࠵? ࠵? × ࠵? ࠵? ࠵? ࠵? + ࠵? ࠵?࠵?࠵?࠵?࠵?࠵?࠵? × ࠵?࠵?࠵?࠵? EMG-Driven Muscle Models 64
EMG-Driven Muscle Models Use surface (or indwelling) EMG to determine activation state of muscles More than one muscle is modeled (direct inclusion of co-contraction in bone on bone force estimates) 65
EMG-Driven Muscle Models We need… 1. EMG activation, MVC activation 2. Muscle properties: PCSA Stress Length-tension Relationship Length-velocity Relationship 66
࠵? ࠵?࠵?࠵?࠵?࠵?࠵? = ࠵?࠵?࠵? ࠵?࠵?࠵? ࠵?࠵?࠵? × ࠵? ࠵?࠵?࠵? × ࠵?࠵?࠵?࠵? × ࠵? ࠵? ࠵? ࠵? × ࠵? ࠵? ࠵? ࠵? + ࠵? ࠵?࠵?࠵?࠵?࠵?࠵?࠵? × ࠵?࠵?࠵?࠵? Components of EMG-driven muscle force equation Muscle force Muscle activation (scaled to MVC) Muscle stress Physiological cross- sectional area Active length factor (accounts for force-length relationship of active components) Velocity factor (accounts for force-velocity relationship Passive stress (accounts for the change force in the passive elements with changes in length) 67

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