Motion sickness symptoms affect approximately 50% of the crew during space travel and are commonly treated with
intramuscular injections of
promethazine. The purpose of this paper is to compare the effectiveness of three treatments for
motion sickness:
intramuscular injections (i.m.) of
promethazine, a physiological training method (autogenic-feedback training exercise [AFTE]), and a no-treatment control. An earlier study tested the effects of
promethazine on cognitive and psychomotor performance and
motion sickness tolerance in a rotating chair. For the present paper,
motion sickness tolerance, symptom reports, and physiological responses of these subjects were compared to matched subjects selected from an existing database who received either AFTE or no treatment. Three groups of 11 men, between the ages of 33 and 40 years, were matched on the number of rotations tolerated during their initial rotating-chair
motion sickness test. The
motion sickness test procedures and the 7-day interval between tests were the same for all subjects. The
drug group was tested under four treatment conditions: baseline (no
injections), a 25 mg dose of
promethazine, a 50 mg dose of
promethazine, and a placebo of sterile saline. AFTE subjects were given four 30-minute AFTE sessions before their second, third, and fourth
motion sickness tests (6 hours total). The no-treatment control subjects were only given the four rotating-chair tests.
Motion sickness tolerance was significantly increased after 4 hours of AFTE when compared to either 25 mg (p < 0.00003) or 50 mg (p < 0.00001) of
promethazine. The control and
promethazine groups did not differ. AFTE subjects reported fewer or no symptoms at higher rotational velocities than subjects in the control or
promethazine groups. The primary physiological effect of
promethazine was an inhibition of skin conductance level. The AFTE group showed significantly less heart rate and skin conductance variability during
motion sickness tests administered after training.