title: Straining GOR tolerance determinations are a measure of G-duration not G-level tolerance.
abstract: Straining gradual G onset rate (GOR) tolerances are considered by physiologists as a measure of G-level tolerance. Using recently developed G-level and G-duration mathematical models, it was found that straining GOR tolerances may well be a measure of tolerance to G-duration. G-duration tolerance was determined to be limited with the onset of fatigue and not cardiovascular insufficiency. G-level tolerances that were predicted using a mathematical model were higher than determined using straining GOR tolerance measurements of subjects on a centrifuge. Also the G-duration tolerance mathematical model showed that those centrifuge subjects had not expended all of their "energy reserve" during their sustained G exposure most probably because of the onset of fatigue. Even if they were able to use all of their potential energy reserve, their G-duration tolerance would not have allowed them to reach the maximum G-level predicted with the G-level tolerance model. It is therefore concluded that the straining GOR tolerance profile, with G onset rates of 0.1G/s, is not a measure of G-level tolerance, as has been assumed, but is a measure of G-duration tolerance. These findings have significant safety implications world-wide since this straining GOR profile is commonly used as a G-level tolerance fighter-pilot-selection determination; i.e. pilot selection standards for G-level tolerance are not a measure of G-level tolerance. In testing equipment design changes, the proper G tolerance profiles must be used to correctly measure its impact on G tolerance.
authors.affiliation: Air Force Research Laboratory, Brooks AFB, TX, USA.
authors.forename: R R
authors.initials: RR
authors.lastname: Burton
mesh_terms: D000222:Adaptation, Physiological; D000337:Aerospace Medicine; D001359:Aviation; D002320:Cardiovascular Physiological Phenomena; D017079:Exercise Tolerance; D005676:Gravity Suits; D006801:Humans; D018471:Hypergravity; D008954:Models, Biological; D018763:Muscle Fatigue; D010807:Physical Endurance; D013997:Time Factors