Dizzy is a neurolgical response to a stimulated sensory hair cells in the ultricle. When these hairs are triggered and move they send a signal to the brain that says "we are moving". WHen they move in unexpected ways they send a "distress signal" to the brain that says "UH-Oh.. We don't know which way the body is going...Sit Down....SIT DOWN NOW" The "sit down" command is interpreted by the brain as "dizzy".
After repeating the offending movements continually over time your brian learns to ignore the "distress signal".
The practice/training one does is much more for developing the
neurological/muscular/joint/etc. controls of the body to
maintain (sense of, and physical reality of) balance throughout
the maneuvers than for ignoring distress. The dancer in control
simply has less or no distress to ignore. That's why good
dancers are "relaxed" rather than "uptight."
I would even say that at some point, for the "same" movements,
the body gets rewired enough to not only stop generating
distress (chemical/electrical) signals, but to generate exhilaration/
pleasure signals. One can get a "high" from movement/spins, and
hence the expression "joy of movement."
Note that this statement by no means states that head position
is the _only_ reason for dizziness/exhaustion. A much bigger and
more general reason for dizziness/exhaustion is simply that many
dancers don't devote enough time and effort (and money) to
figuring out what needs to be done.