The effects of G-Force

If you've ever been to an airshow with flight demonstration teams with either the Navy's Blue Angels or the Air force's Thunderbirds, you've probably seen them pull some stunts that seem almost impossible according to the laws of physics. The fact is these pilots are highly trained and have over 1,000 flight hours. Notice that they do not wear the flight suits or helmets that regular fighter pilots wear? This is because they have performed the maneuvers so many times that they know what their body will experience. When the Blue Angels take a passenger up in their #7 plane they must be able to manage the stress that the G-Force will put on their body. If they can't the result can be very dangerous, the passenger can black out, and their blood could rush to their head. In order to prevent the dangers from occurring pilots tell the passengers to tense every muscle in their body just before the maneuver that is being performed. This constricts the arteries and veins and doesn't allow the blood to flow as freely as it could with out the muscle contraction. Passengers are also told to use the "Hick Maneuver" It's hard to explain so a video showing it will follow.

http://www.youtube.com/watch?v=U1e93JU4Gn4

Notice how Adam had to keep using the "hick maneuver", The pilot was talking to him the whole time, not once did you hear a "hick" from the pilot.