Any ideas to simulate full body muscle - beyond constructing many line elements and is, in any case , impractical for , say , the heart , or tongue. For small contracture one can make the brick elements orthotropic thermal and use a negative alpha. But this is "computationally expensive" and can be applied to only one large muscle, not in situations that have overlapping muscles.
What is needed a ( multi ) directional force field applied to internal nodes, . This can be done in some other FEA packages, but I've not seen a way to do so in Autodesk FEA. ( Autodesk Maya actually approximates this , but .... )