I haven't felt dizzy or sick after doing steep turns or stalls. I spun the 172 by accident and thought it was actually a mild manuever, been on rollercoasters that were more violent IMO. Anywho, I've talked with my intructor and was told that he got sick from doing repeated spins during training. He was spin training for a job flying skydivers and had to land during his training so he could spew on the ground instead of the plane.

KC135guy