Effects of Voluntary Neck Extension on Cerebral Blood Flow, in Breath-hold Divers Ending an Apnoea of Two Minutes or More.

"The included subjects will make an apnea of two minutes or more, sitting on a chair with cold strips on the face, initially with the head in neutral position. Then, when they feel the end of their apnea, they will have to raise their left hand to signal it to the Doppler manipulator, who will then realize the apnea reference measurement.~As soon as this is done, the subjects will be asked to perform an extension of the neck, so as to look at the ceiling. A final measurement will then be made in apnea, the head always in extension. Subjects then resume their breathing in this same position. A final measurement will then be made."