During the launch and re-entry phases of spaceflight pilots of military fast jets, civilian aerobatic pilots and astronauts are frequently and repetitively exposed to high G forces, for which the human body is not fundamentally designed. This unique book examines the nature of the high G environment and its physiological effects on the various systems of the human body. It draws together the accumulated knowledge of human exposure to high G, resulting in a definitive volume on its physiological effects and countermeasures.