Dizziness

You know that feeling you get when you spin around really fast and then stop? In the cartoons this feeling is usually illustrated with a swirl and some stars around the head. But actually the whole body has this spinning feeling. You can feel it in your knees and elbows too.

With this sort of disorientation it feels as if there is a body that is now still, and a second body that hasn’t stopped spinning yet. As you gain your baring, it feels as if that "other" body comes back inside.

A similar thing happens to me (and I think most people) when I am laying down very relaxed and still. I feel my body start to move around slowly, even though I know I’m not actually moving. I can control it, but it requires that I relax first, it feels like I'm letting myself drift.

Well this feeling of the body drifting out is an important aspect of Baguazhang, Taijiquan, and Internal Martial Arts practice in general. When I soften my movement to the point where I feel like I’m continuously melting, as I turn side to side it feels like my body keeps turning even after I have stopped. If I follow the "other" body, my solid body will lose its integration, so the correct response is to stop and re-integrate. Then I can turn the other way and repeat the experience on the other side.
When doing a form, or practicing push-hands, or even fighting, we control this 'other' body, circling it around and even throwing it like a light silk blanket over our opponents.

A significant number of martial arts techniques gain efficacy through disorienting the opponent in one way or another.  Likewise, a significant amount of training is designed to familiarize us with strange sensations and orientations so that when they happen in a fight we don't get disoriented.

There have been a few studies that show taijiquan training improves balance in older people.  I like to point out that his is "fallout" from, or a  "sidecar" to, the main project of martial training and cultivating weakness, but never the less it is a nice benefit.