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Publication AbstractsMathematical Models for Predicting G-Duration TolerancesRussell R. Burton, DVM, Ph.D.Aviat Space Environ Med 2000; 71:981-90 AbstractMathematical models that predict fatigue-based G-duration tolerances for relaxed and straining subjects are developed and validated using published data. These models are based on regression analysis calculations using published G-duration tolerance data of relaxed subjects exposed to 3-5 G and subjects exposed to 6-9 G using an anti-G suit and performing the anti-G straining maneuver. These G-duration models are derived from published G-level tolerance models based on intravascular hydrostatic pressures and physiologic responses to maximum voluntary contractions (MVC%). Included in the validation of these models are the baroreceptor and muscle contraction cardiovascular reflexes that support arterial BP. A basic energy pool that supports a G-duration of 140 s for G exposures >5 G is theorized. Because of the long duration of sustained G exposures in these models, the physiologic dynamics involved in predicting straining G-duration tolerances, are identified and validated using different time periods, i.e., Phases I and II. These models, based on sustained G exposures to a constant G level are also applicable to exposures of variable G levels known as simulated aerial combat maneuver (SACM) G-profile tolerances. G-duration tolerances > 9 G are predicted using these models for subjects using reclined-seat backs and positive pressure breathing.Keywords: G-duration tolerance, acceleration tolerance, human tolerance to G, sustained G tolerance, simulated aerial combat maneuvers (SACM), exercise physiology. Information on subscribing, and on obtaining copies of an article or of an entire issue. Table of Contents for Volume 71, Number 10 of the ASME journal.
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