Gimbal

I guess it's quite hard, because of the light difference you decided to use (black background and parts of the bodies in the light). Personally I would suggest you not to move too fast or to try to keep always the same distance from the subject...

Using the auto-focus mode it's a shit with such a difference of brightness...
But maybe consider also that a not sharpen image could also result in something interesting!!
Good luck!
;-)