Research of Hyperbaric Oxygen Pretreatment to Improve The Lower Body Negative Pressure Endurance of Pilots with Poor Acceleration Endurance

Background: To investigate the effect of hyperbaric oxygen preconditioning (HBOP) on improving the lower body negative pressure endurance of pilots with poor acceleration endurance. Methods: ： 30 pilots with poor acceleration endurance were subjected to multiple HBO（hyperbaric oxygen ,HBO） cabin and 3 times HBO exposure. Oxygen inhalation was performed for 95min, once a day (time was fixed at 14:30-16:15 PM in the HBO cabin), for consecutive 3d. The lower body negative pressure endurance and blood indexes were measured before and after HBOP using the subjects' own before-after control design. Lower body negative pressure endurance adopts stepwise increasing scheme, that is, continuously increasing LBNP load:-20mmHg·1min、-30mmHg·3min、-40mmHg·5min、-50mmHg·7min, etc . Results: : The cumulative stress index of subjects before HBOP was (-856.13±273.76min·mmHg), and that after HBOP was (-1237.42±385.50min·mmHg). The cumulative stress index after HBOP increased significantly (t=7.750, P<0.05), namely lower body negative pressure endurance significantly improved. After that, 30 people underwent centrifuge reexamination, and the passing rate of 4.0G10s reached 93.3%.After HBOP, diastolic blood pressure increased (t=-3.252, P<0.05), heart rate slowed down (t=5.493, P<0.05), blood oxygen saturation (SaO 2 ) increased (t=-3.08, P<0.05), but there was no significant difference in systolic blood pressure.Blood lactic acid (BLA) was lower than that before HBOP (t= 2.186, P<0.05); Adrenocorticotropic hormone (ACTH) was not significantly different from that before HBOP. Conclusion: HBOP can improve the lower body negative pressure endurance and centrifuge acceleration endurance of pilots with poor acceleration endurance, and its mechanism may be related to the improvement of autonomic nerve function and the enhancement of human energy metabolism.