Muscle strength

I am trying to simulate muscle with zero strength of the 3E element type.
However when I type in the following code:
F0 = .StrengthScaleShank*.PCSAfactorPCSA0;

I do not get a force output (fm) of zero. If however I use the same code for the simple muscles I get a force of zero. I was wondering why this was happening and if there is something I must do in addition

Maybe this is due to the the muscle fibers having a defined length? I don’t know about this exactly but perhaps there will be a force if the distance between the two muscle attachment point is greater than the defined muscle length (something like stiffness * delta(length)). The simple muscle doesn’t have a stiffness parameter while the hill type has the PEFactor which seems to be stiffness of the parallel elastic element.

PEFactor: Relative stiffness parameter for the parallel elastic element. PEFactor times Lfbaris the fiber lenght at which the parallel elastic elements produce a force of F0.

To see if this theory is true maybe you could have a look at the Lfbar and the distance between the two RefFrame which define the attachment points.