The study was conducted to observe the protective effect of sea-buckthorn flavone (SF) on myocardium in rat subjected to long-term exhausted exercise.Fifty six-week-old SPF-grade male SD rat were randomly divided into normal group,model group,and SF low,medium and high dose(100,200 and 400 mg/kg) group.An exercise induced myocardial injury model was established through six-week exhausted treadmill training.Inflammatory reaction in myocardium,oxidative stress related index and the serum markers of myocardial injury were detected by ELISA;myocardial cysteinyl aspartate specific proteinase-3 (Caspase-3) protein expression was detected by the immunohistochemical method;protein expressions of myocardial BCL2-associated X (Bax),B-cell lymphoma-2 (Bcl-2),type I Collagen (Collagen-Ⅰ),and connective tissue growth factor (CTGF) were detected by Western blot;myocardial tissue morphology and collagen deposition were observed by HE and Masson staining.The results showed that compared with the model group,the levels of serum aspartate aminotransferase (AST),creatine kinase MB (CK-MB),cardiac troponin I (cTn I),collagen volume fraction (CVF),and the expression of Caspase-3,Bax,and Collagen-I proteins in the myocardial tissue of rats in each dose group of SF were significantly reduced (P<0.01),while the expression of Bcl-2 protein and Bcl-2/Bax ratio in the myocardial tissue were significantly increased (P<0.01);Medium to high doses of SF can significantly reduce malondialdehyde (MDA),interleukin-1β (IL-1β) ,Interleukin-6 (IL-6),tumor necrosis factor-α(TNF-α) and expression of CTGF protein in myocardial tissue (P<0.01),increase the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in myocardial tissue (P<0.01).The results of the study suggested that medium and high doses of SF could inhibit oxidative stress,inflammatory reaction,cell apoptosis,and fibrosis in the myocardial tissues of rat subjected to long-term exhausted exercise,and alleviate myocardial injury.It was found that the effect of a high dose was better.