Yup! Those are gutters! Sometimes just really studying comics you like, and seeing how they depict action and movement can help give better story and time sense to a comic. I just recently finished Locke & Key-- great since of movement with well chosen framing.
As for your new panels you're showing, have you considered not having them? Her Line of Action is strong enough to convey she is moving forward in the space. So unless she's super human and incredibly fast, maybe it can work without the blur.
Without knowing the context of the other panels... if this is a intense, dramatic moment, maybe have a tighter shot closer in on her?
If you really want to keep them, I prefer the lower opacity.
(also, if you want fast speedy action fiights, maybe checking out The Flash will help).