Tilt-table testing as a predictor of + GZ tolerance

Abstract

BACKGROUND: G-tolerance assessment is an essential element of both military pilot and pilot candidate evaluation. AIMS: Attempt at prediction of individual relaxed + Gz tolerance on the basis of head-up tilt (HUT) testing. SETTINGS AND DESIGN: In two stages, 20 healthy men at the mean age 21.5 years took part in this study. The first stage, a 45 min, HUT test was performed using the Westminster protocol. During the second stage each underwent a centrifuge evaluation in response to gradual onset rate profiles. METHODS AND MATERIAL: In each subject, heart rate (HR) and blood pressure (BP) before and at 2, 15 and 45 min of the tilt-test were recorded. The gravity-load centrifuge (GOR) studies were carried out [following the standard GOR programme, at 0.1 G/s rate of gravity load increase until the gravity load tolerance limit (loss of peripheral vision) was reached]. STATISTICAL ANALYSIS USED: Relationships between variables were explored using Kendall's tau-B correlation coefficient. The critical P-level was one-tailed 0.05. RESULTS: In four of 20 subjects (20%), vasovagal syncope occurred during the tilt test. G-level tolerance of this group (of +Gz accelerations) lay in the range from +4 to +8.1 Gz, (+5.72 ? 0.86 Gz average) and was comparable to the group without syncope. Loss of consciousness did not occur in any subjects during the centrifuge test. No statistically significant correlation was observed between HR and BP during tilt test and tolerance to +Gz accelerations. CONCLUSIONS: The result of tilt testing, carried out according to the Westminster protocol, was not useful in predicting individual tolerance to +Gz gravity loads.

Adaptability of a jump movement pattern to a non-constant force field elicited via centrifugation

“…levels below 1g lead to inferior results, and g levels above 1g do not seem to produce considerable benefits, but increase knee joint moments and might not tolerated as well, as anecdotal evidence from one participant with a pre-syncope at 1.5g suggests and literature confirms for higher g-levels [18]. Whether a longer familiarization period in the centrifuge would allow participants to develop a movement pattern that is closer to the natural one, resulting in higher peak forces, has to be answered in a future training study.…”

Endoplasmic Reticulum Is Involved in Myocardial Injury in a Miniature Swine Model of Coronary Artery Stenosis Exposed to Acceleration-Associated Stress

“…In addition, due to mechanical force and severe hemodynamic changes, cardiomyocytes and muscle fibers will suffer from some damages. Some authors have confirmed the effects of high +Gz were similar to hemodynamic changes observed in ischemia reperfusion (I/R) [ 12 ].…”

Ground Vasovagal Presyncopes and Fighter Pilot Fitness: Aeromedical Concerns

“…It was observed that the four of those tested who demonstrated vasovagal syncope during the tilt test had a G z -level tolerance from 1 4 to 1 8.1 G, which was comparable to the group without any syncope. Nobody lost consciousness during the centrifuge testing ( 14 ).…”