physiological changes that occur in the body when it is subjected to intense gyrational or centrifugal forces, as in tumbling and spinning. Tumbling and spinning are a hazard to pilots who have been ejected from a moving aircraft.

Tolerance levels to rotational stress depend somewhat upon which part of the body is acting as the centre of rotation and how long the stress is endured. When the heart is the centre of rotation, unconsciousness can occur at 169 revolutions per minute for only a 3- to 10-second exposure, and the results can be fatal if such rotation is sustained for two minutes. At 150 revolutions per minute the blood pressure is drastically lowered so that output from the heart is almost stopped. Hemorrhages can occur in the eyes, brain tissue, skin, sinus cavities, and middle ears; pain and severe headaches can be produced and may last for several days after the exposure. Other complications that can arise are nausea, vomiting, pooling of blood in the extremities, disorientation, and blurring of vision.