alexcolle
There are people much more academically inclined that I'm sure will have an opinion.. Here's my 2c anyway. 🙂
Ziva nomenclature defines bones as kinematic objects. In that respect usually it's the muscles which react to bones that are already in motion (motion capture, hand keyed), to give the effect that the muscles are pulling the bones around.
That said, you're not prohibited from trying to drive bones with muscles. You'd have to define your bone meshes as dynamic meshes ("zTissues" in Ziva VFX)
You can set your dynamic bones to have similar density/ stiffness to real bones. You can attach muscles (also zTissues) and start contracting muscles to pull on the skeleton.
Ziva VFX does not produce torque numbers