You can see it for example in the DualsCombo_1 animation between Frame 10 and 30. (And all other fast moving animations)
i added constraints,stretch to, rotate to, etc. to simulate a muscle behavior in my animations. The problem is that the animation, with fast movements, behaves like a jiggling rag doll. The head drags behind while rotating. Can anyone explain why does it happens and how to avoid it?