RESUMO
<p><b>AIM</b>To explore the influence of hyperbaric oxygen (HBO) preconditioning on anoxic resistance and anti-weariness at high altitude.</p><p><b>METHODS</b>(1) SOD, MDA, NO, NOS, BLA and BUN of 20 youths living at 3 700 m altitude for half year were tested, then they were divided into group A (n=10, received HBO pretreatment twice) and group B (n=10, received HBO pretreatment 5 times) randomly. They were asked to pedal the EMG-bicycle-ergometer at the second and eighth day, and then the same items were tested. (2) 29 youth who would go to Astronomical Spot (5200 m) were randomly divided into group HBO (n=11, received HBO pretreatment once per day for 2 days at Yecheng (1400 m)) and comparison group (n=10). When they reached I Astronomical Spot, thematic biochemical index were investigated. (3) When 20 youth reached Thirty Milepost Barracks (3700 m) at the second day in their way to Immortal Gulf (5380 m) from Yecheng were randomly divided into group HBO (n=10, received HBO pretreatment once per day for 3 days) and comparison group (n=10). When they reached Immortal Gulf, the thematic biochemical index were investigated.</p><p><b>RESULTS</b>(1) SOD, NO, NOS were increased and BLA, BUN, MDA were decrease in group A compared with that in group B until the eighth day, there was significant difference (P < 0.01). (2) SOD, NO, NOS were increased and BLA, BUN, MDA were decrease in group HBO compared with that in comparison that in group, there was significant difference between groups (P < 0.01, or P < 0.05).</p><p><b>CONCLUSION</b>HBO could enhance the activity of anti-oxidase and the cleared ability of lactic acid, and the effect of anti-weariness could last for 8 days.</p>