12/7/2023 0 Comments Max g force![]() To bridge this gap, we designed this study to evaluate the correlation of the physiological responses and anthropometric factors with G tolerance by analyzing a high G training database. To the best of our knowledge, there are few large-scale data analyses from centrifuge training investigating the correlation between trainees’ physiological responses (e.g., HR changes) and anthropometric parameters and G tolerance. However, the results regarding correlations between physiological responses and anthropometric factors and pilot G tolerance have been inconclusive. Some former studies have demonstrated that G tolerance in the human centrifuge is positively associated with the following parameters: age, weight, flight hours, straining G tolerance, and AGSM proficiency. The USAF prioritized pilots with conditions such as low seated systolic blood pressure (SBP), a tall and slender body, less total flying time, etc. Due to GLOC-related accidents, the United States Air Force (USAF) initiated a high G training program for jet pilots in 1985. Human centrifuge training is commonly accepted as an effective and safe method to test the G tolerance of fighter pilots on the ground. In general, the activation of HR induced by sympathetic tone takes several seconds after exposure to the G environment. ![]() HR acceleration, primarily representing the activity of the baroreceptor reflex during rapid onset, is expected to be related to the G tolerance of the human body. ![]() reported that changes in the HR were dependent on the level of G stress. When blood pressure at the carotid sinus declines due to acceleration, an increase in the heart rate (HR), which is regulated by the autonomic nervous system, is one of the initial compensatory physiological responses. Several well-known countermeasures have been used to mitigate the risk of GLOC, including the baroreceptor reflex, anti-G suits, and anti-G straining maneuvers (AGSMs). While incapacitated, pilots have no control over their plane, and the consequences of GLOC could be tragic. If the magnitude of the G force surpasses the tolerance of the human body, pilots experience stagnant hypoxia and even suffer from G-induced loss of consciousness (GLOC). Because hypergravity forces the blood of the pilot to pool in the lower body, the arterial blood pressure is directly affected by G force. Among the six axes of gravity in flight, the direction from head to toe (+Gz, commonly called G force) is the main safety concern of experts in aerospace and occupational medicine. However, military pilots are occupationally exposed to extremely high gravity environments. Modern high-performance aircraft are capable of agile maneuvers to meet the demand of acrobatic battles in the air. Factors, including body mass index, relaxed and straining G tolerance, and AGSM, were found to be negatively correlated with the outcome. ![]() The chances of failure were inversely related to the HR increase percentage ( p for trend <0.001). The group with a small heart rate (HR) increase (less than 10%) during the first 1–5 s of the 7.5G profile had a nearly ten-fold higher failing chance compared with the large HR increase group (adjusted odds ratio: 9.91 95% confidence interval: 4.11–23.88). There were 873 trainees who underwent 7.5G profile training, 44 trainees (5.04%) could not sustain the test for 15 s. Variables were collected to examine their correlations with the outcome of 7.5G sustained for 15 s (7.5G profile). We retrospectively reviewed the training records of student pilots who underwent high G training. The aim of this study was to investigate the physiological responses and anthropometric factors correlated with G tolerance. Some factors that may affect G tolerance have been reported but are still debated. Human centrifuge has been used to examine the G tolerance and anti-G straining maneuver (AGSM) techniques of military pilots. Fighter pilots experience decreases in blood pressure when exposed to hypergravity in flight. Gravity in the head-to-toe direction, known as +Gz (G force), forces blood to pool in the lower body.
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