AGSM

A form of anti-G straining maneuver — Any of various techniques to increase G-tolerance and reduce G-LOC incidences that involve emptying the lungs while straining the muscles to force oxygenated blood to the brain. Most common techniques include visualizing a walnut held between one's buttocks, and trying to crush it, or tensing the abdominal and chest muscles, possibly while bent over at the hips.