Abstract: Objective:By supplementing the astaxanthin,the effects if astaxanthin could mediate Nrf2 and reduce myocardium oxidative injury in rats after high intensity training of 6 weeks were investigated in the research. Methods:7-week SD male rats were divided into 3 groups randomly:control group(C group,n=10),high intensity training group(HT group,n=15),astaxanthin and high intensity training group(HTA group,n=15). The rats in HTA group were intragastrically daily administered astaxanthin 20 mg/kg and were intragastrically administered equal amount of soybean oil in HT group during the training day.The serum cardiac troponin I(cTNI),myocardial apoptosis index,the expression of myocardial B cell lymphoma/leukemia 2(Bcl2),Bcl2 associated x protein(Bax),nuclear factor-E2-related factor 2(Nrf2),heme oxygenase-1(HO-1),myocardial malonaldehyde(MDA),superoxide dismutase(SOD)and total antioxidative capacity(T-AOC)activity were detected at 24 h after the last training.Results:After 6-week of high intensity training,compared with C group,the serum cTNI,myocardial apoptosis index,the Bax expression and myocardial MDA were significantly higher in HT group(p<0.01). The Bcl2/Bax,the expression of HO-1,SOD and T-AOC activity were significantly lower(p<0.01). After the intervention of 6-week astaxanthin intragastrical administration,in HTA group,the serum cTNI,myocardial MDA,the myocardial apoptosis index,the Bax expression were significantly lower than HT group(p<0.05). Finally,Bcl2/Bax,SOD,T-AOC activity,the Nrf2 expression and HO-1 were significantly improved(p<0.05). Compared with C group,all these indexes increased significantly besides Bcl2 and HO-1(p<0.05). Conclusion:These results demonstrate that supplement of astaxanthin can mediate Nrf2 signaling pathway,and elevate the expression of Nrf2 and HO-1.It can also effectively increase the activity of SOD and T-AOC,after that the astaxanthin is helpful to alleviate the myocardial oxidative level and myocardial apoptosis which are caused by 6-week high intensity training. Finally,the structure and function of heart tissue are back to normal.