The Effect of Exercise Training Intensity on Cardiac Regeneration Capacity in Rats with Myocardial Infarction

The aim of this study was to investigate the effect of exercise training intensity on cardiac regeneration capacity in rats with myocardial infarction (MI). Male wistar rats were exposed to LAD coronary artery ligation surgery and then the creation of MI was confirmed by echocardiography. Four weeks after surgery, the rats with MI were randomly assigned to these groups: low intensity training (LIT), moderate intensity training (MIT), high intensity training (HIT), and Sham, plus a healthy control group (Con). Training groups performed the exercise training protocols for 6 weeks, 5 sessions per week. The rats were sacrificed after the exercise training intervention, and the obtained data were analyzed by one-way ANOVA and LSD test. The results showed a significant difference in the values of ejection fraction, fractional shortening, mRNA Gata4, and mRNA Tbx5 among all groups (P=0.001). LSD test results demonstrated that ejection fraction and fractional shortening values increased significantly in all three exercise training groups compared with the sham group. However, contrary to this increase, their values in the Con group was significantly higher than the groups with MI. Results also showed that mRNA Gata4 value significantly increased in the LIT group compared with the MIT, HIT, Sham, and Con groups. However, mRNA Tbx5 values showed no significant changes among the groups with MI. Only mRNA Tbx5 values in Con group were significantly higher compared with the groups with MI. In conclusion, regardless the intensity, exercise training increases cardiovascular function in rats with MI. However, it seems that low intensity exercise is a more effective agent in increasing cardiac regeneration capacity in rats with MI.