@DaveB
...your brain will respond to the motion and try to keep your legs balanced, something that doesn't work cause your actually not in a moving ship.
Adding this, because I forgot to say it in my last reply and editing this late just doesn't feel right...
I'm an old sailor. I know all about how you need to train the brain to treat input from the eyes and from the balance centers as separate data streams, not an integrated whole. It always takes a day or two on board to remind it of that and "get your sea legs back" and on the occasions when a bit of Harry Roughers showed up sooner than I completed the process the fishies had a few nice breakfasts on what had been my breakfast a few hours before. That's what the lee rail is for.
ED hasn't even come close to hitting my motion sickness threshold yet but I'm aware it could so I'm spending a little time each day in the simulated zero-g of the Mission:ISS app to make sure I become - and stay - properly acclimated to VR and can stand up in a "moving environment" without either falling over or getting nauseous. That's a much more challenging environment in terms of conflicting inputs to the brain than standing on your feet while your ship is maneuvering in ED