Comparison of susceptibility to motion sickness during rotation at 30 rpm in the earth-horizontal, 10 degrees head-up, and 10 degrees head-down positions.

Normal persons rotated about an Earth-horizontal axis vary in their susceptibility to motion sickness. The purpose of this experiment was to measure, intraindividual differences in susceptibility in 12 subjects when rotated 10 degrees head up and 10 degrees head down as well as in the horizontal position. Subjects assumed the test-position 60 min prior to rotation, thus providing an opportunity for translocation of body fluids. Physiological and psychophysical measurements were conducted throughout the experiment. There were no intraindividual differences in susceptibility to motion sickness in the three positions tested, although there were significant differences in vital capacity, demonstrating the expected fluid shifts. It was concluded that, in the sample of subjects tested, short-term effects of fluid shifts greater than those that would be manifested in zero gravity had no definite effect on motion sickness susceptibility.