You went to Six Flags and bypassed the 'loop the loop' coaster? You missed a treat. The coaster is shaped in such a way that at the bottom of the drop as you change direction, the 'G' forces acting on you are kept to a reasonable level to avoid any potential for blackouts. You might want to consider the Physics as to what causes these G forces. I don't recall feeling much of anything last time I rode it, it just made me feel heavier I guess, it happens so fast. Coming down is the worst part , being somewhat weightless on the descent with that 'stomach in your throat' feeling (that I believe the astronauts also get when in apparent weightlessness in orbit, a feeling that quickly goes away once they adjust to the zero G state). Then there's Disney's 'Twilight Zone Tower of Terror ' ride, pure free fall and then some, as the ride initially accelerates downward greater than the acceleration of gravity, causing you to be slightly lifted off your seat at the initial drop. Again the 'drop' is worse than the 'stop', which although abrupt, is nonetheless controlled to to prevent high forces from being imposed upon you.