Effects of hyperbaric oxygen preconditioning on human energy metabolism under high altitude hypoxia

Objective To investigate changes in human energy metabolism both before and after physical load under high altitude hypoxia and effects of hyperbaric oxygen preconditioning (HBOP). Methods Six healthy male soldiers who used to live in the plain region, joined the army, and moved to the plateau region 6 to 12 months ago were enrolled for our study. The levels of glucose(Glu), blood lactate(BLA), lactate dehydrogenase(LDH)and Na+-K+-ATPase both before and after physical load were detected before HBOP, and 5 and 7 days of HBOP as well. The mode of physical exercise was 5-minute stair-climbing, at a rate of 25 stairs a minute, with the height of the stair being 30 cm. A pacemaker was used to control the rate of climbing up the stairs and record the time, with the physical intensity being equivalent to 650 kg·m/min. Results Following HBOP, no signficant changes could be found in the levels of Glu, BLA, LDH and Na+-K+-ATPase at rest, when compared with those before HBOP (P>0.05). However, 5 and 7 days after physical load, the levels of Glu [(5.31±0.27) and(4.61±0.26)mmol/L] were significantly increased, as compared with those before HBOP [(4.23±0.25) mmol/L], with statistical signficance(P<0.05 or P<0.01). The levels of BLA, LDH and Na+-K+-ATPase after 5-day HBOP were [(1.00±0.03)mmol/L, (216.33±16.87)U and(5.65±0.51)μmolPi/mgpr.h], and the levels of BLA, LDH and Na+-K+-ATPase after 7-day HBOP were [(0.92±0.04)mmol/L, (192.38±15.06)U and(5.38±0.38)μmolPi/mgpr.h], which were obviously lower than those before HBOP [(1.08±0.07)mmol/L, (244.24±21.82)U and(6.49±0.46)μmolPi/mgpr.h], also with statistical signficance(P<0.05 or P<0.01) Conclusions Short-term HBOP could significantly improve energy metabolism of military personnel at high altitude with physical load, accelerate glycogenolysis and elevate Glu level, lessen the accumulation of BLA after physical load, decrease the activity of LDH and Na+-K+-ATPase and enable muscles to make better use of oxygen, thus reducing fatigue and improving working efficiency. Key words: Hyperbaric oxygen; Physical load; Glucose; Blood lactate; Lactate dehydrogenase; Na+-K+-ATPase