Short Duration Hypoxic Preacclimitizatiom Strategies Reduced Acute Mountain Scikness Symptoms And Its’ Transporting Mechanisms

Purpose:The purpose of this study was to select the sensitive physiological and biochemistrical index through an acute normobaric hypoxia exposure model (FiO2:～10.19%, duration:6 h); Choosing 19 AMS sensitive subjects(LLS>3) completed 2 same hypoxia dose, different model preacclimatization strategies (AMS-EX4 vs AMS-S4), then examined the the model effects of short duration normobaric hypoxia preacclimatization on reducing acute mountain sickness symptoms and its sustained effect. This study attempted to find the relation between the subjects suscepbilities and the mechanism of oxygen’s release and transporting.Methods:46 healthy male college students completed the acute normobaric hypoxia exposure model (FiO2:～10.19%, duration:6 h); wrote the Lake Louis consensus scoring of AMS and choosed 19 subjects whose’s LLS>3 divided into 2 groups AMS-EX4 and AMS-S4. The 2 groups of AMS sensitive subjects then completed 2 preacclimatization strategies (AMS-EX4, AMS-S4) in hypoxic conditions.In trail AMS-EX4,9 subjects exposed in normobaric hypoxic conditions of 2300-5000m equivalent altitude for 4 hours per day lasting 7 days, in the hypoxic conditions the subjects exercised 1 hour per day on treadmill or ergometry bicycle controlled their heart rate about 170 b/min and rested the 3 remainding hours. In trail AMS-S4,10 subjects slept in normobaric hypoxic conditions of 2300-2800-3000m equivalent altitude for 6 hours per night lasting 3 nights, then exposed in normobaric hypoxic conditions exercised 1.75 hours per day on treadmill or ergometry bicycle controlled their heart rate about 170 b/min and rested the remainding 0.75 hour lasting for 4days. All the subjects completed a 6-hours acute normobaric hypoxia expourse before (6H)the preacclimatization, after the preacclimatization (8D), the first (1W) and second (2W) weekend after completed the preacclimatization. In normoxia (BL) condition and the four 6-hours 5000m equivalent altitude hypoxic conditions, every subject was examined the physiological and biochemistrical index, such as LLS score, HRV, HVR, lung function, SpO2, eNOS, ET-1, blood rheology, AE1,2,3-DPQ Hb and reticulocytes, during resting and exercised states.Results:Ⅰ:6-hours acute exposoure in normobaric hypoxia condition the AMS incidence was 58.70%. when exposed in acute 6-hours normobaric hypoxia, AMS subjects’ index of ΔSar,/ΔSae, HVRr, HCRe, Retic% and H-Retic% were significantly higher than NON-AMS subjects (p<0.05); when exposed in acute 6-h normobaric hypoxia, AMS subjects’index of SpO2r, SpO2e, eNOS,2,3-DPG were significantly lower than NON-AMS subjects (p<0,05); II:LLS scores of AMS-EX4 and AMS-S4 subjects on 6H were significantly higher than its on 8D,1 W,2W(p<0.05); the scores of AMS-EX4 subjects on 8D were significantly lower than AMS-S4 subjects (p<0.05); Ⅲ:all the other physiological index such as HVRr, ΔSar、ΔSae、 SpO2r、SpO2e on 8D,1W,2W were significiantly changed compared to them on 6H (p<0.05), but there were no differences between the groups (P>0.05).Conclusions:Ⅰ:This normobaric hypoxia model our study used which AMS accidence was 58.70%, can evaluated the research of AMS; Ⅱ:The index of ΔSar, ΔSae, SpO2r, SpO2e, HVRr, HCRe were the excellent predictors of AMS suscepbilities. In acute normobaric hypoxia expourse, the subjects whose blood vessels diastolic function (eNOS) was the dominant function were higher hypoxia tolerance. The subjects whose oxygen dissociation curve right shifting (2,3-DPG was high) were hypoxia tolerance better. The subjects whose reticulocytes (Retic%, H-Retic%) significantly increased were bad hypoxia tolerance; Ⅲ:The short duration (7days) normobaric hypoxia preacclimatization strategies could reduce the AMS subjects’symptoms. The preacclimatization strategy of AMS-EX4 reduced the subjects’LLS and was better than the preacclimatization strategy of AMS-S4. The 2 preacclimatization strategies all could reduced the LLS sustained for 2 weeks, but there was no difference on the sustained effects; Ⅳ:the improvement of HVR, EIAH, blood rheology and the release of oxygen are responsible for the effects of the short duration normobaric hypoxia preacclimatization on reducing the AMS symptoms; Ⅴ:All the index our study choosed couldn’t demonstrate the significant difference of preacclimatization model (AMS-EX4 vs AMS-S4) or the sustained effects.