Abstract: Objective: To study the effects of chronic intermittent hypoxia training on rat myocardial ATP content Na⁺,K⁺-ATPase and Ca²⁺,Mg^2- ATPase activities.Methods: Thirty-two male Wistar rats were divided into chronic group,acute group and control group according to the low oxygen training program,The rats in chronic group were subjected to chronic intermittent hypoxia training,daily training at 3 km simulated altitude for 4 h for 2 weeks,then daily training under 5 km simulated altitude for,4 h for the next 2 weeks,finally placed for 4 h under 8 km simulated altitude.The rats in acute group were immediately under 8 km simulated altitude for 4 h,and the rats in control group were no hypoxic training.After the expiry of the low oxygen,the rats were executed,myocardial mitochondria were separated and ATP enzyme activities were determined.Results: In chronic group,ATP enzyme content was(9.04±4.71) μmol·mg^-1·h^-1,which was higher than(4.96±1.17) μmol·mg^-1·h^-1 in acute group and(4.38±0.95) μmol·mg^-1·h^-1 in control group(P<0.01).In chronic group,Na⁺,K⁺ ATPase activity was(2.55±1.41) μmol·mg^-1·h^-1,and(2.66±1.07) μmol·mg^-1·h^-1 in acute group,(3.08±1.37) μmol·mg^-1·h^-1 in control group,there had no statistical difference among the three groups(P>0.05).In chronic group,Ca²⁺,Mg²⁺ ATPase activity was(1.17±0.34) μmol·mg^-1·h^-1,and(1.28±0.42) μmol·mg^-1·h^-1 in control group,which had no statistical significance between the two groups(P>0.05),but was higher than(0.58±0.14) μmol·mg^-1·h^-1 in acute group(P<0.01).Conclusions: Chronic intermittent hypoxia training can enhance Ca²⁺,Mg²⁺ ATPase activity,at the same time can significantly increase ATPase content,which can improve myocardial motion function,the rats can adapt the hypoxic environment.