The effect of exercise preconditioning with high-intensity interval training on cardiac protection following induction of myocardial infarction through mitochondrial dynamic changes in cardiac tissue in male rats

Exercise training prevents the adverse effects of Myocardial Infarction (MI) and Ischemia/Reperfusion (I / R) and it seems that mitochondria have an important role in exercise-induced cardioprotection. So, the purpose of this study was to investigate the effects of exercise preconditioning with 4 weeks of High-Intensity Exercise Training (HIIT) on cardiac damage and mitochondrial dynamic proteins as effective factors in cardiac protection following MI. Twenty Male Wistar rats were randomly divided into 4 groups HIIT + MI, MI, HIIT, and Control. Training groups performed 4 weeks (5 days per week) of high-intensity interval training. HIIT protocol consisted of 10*1min running intervals that were separated by 2 min rest. Training intensity varied every week. For induction of myocardial infarction, a subcutaneous injection of isoproterenol was used. Creatine Kinase (CK) and lactate Dehydrogenase (LDH) were measured in serum and Drp1, and Mfn2 gene expression were measured by the real-time PCR method in the heart tissue. The results of the present study showed that CK and LDH in MI were significantly higher in HIIT + MI (p < 0.05). myocardial infarction results in a significant increase in Drp1 gene expression in the MI and HIIT + MI groups relative to the Control group. The expression of the Drp1 gene was lower in the HIIT + MI group than in the MI group, but it was not statistically significant. Also, the results demonstrated that Mfn2 was no significant difference between the groups (p > 0.05). It seems that four weeks of exercise preconditioning with HIIT training reduced injury and necrosis in cardiac tissue and can increase cardio-protection. Also, no significant effect was observed in reducing Drp1 expression due to HIIT which may indicate the need for a longer training period.