Is there a Muscle System for Blender?

I know, you can create a muscle-like effect with Shape Keys, but this way you have no jiggling, so it’s not realistic.

Blender does not have a “Muscle System” built in. If you look around Animation and Rigging, you’ll find some people experimenting with rigs that simulate muscle systems. You can add jiggles many different ways, I suppose the most automatic is with Soft Bodies. Has a nice ring to it, no?