The Effect of Training Exercise Intensity on Left Ventricular Structure and Function in Rats with Myocardial Infarction

The aim of this study was to investigate the effect of training exercise intensity on left ventricular structure and function in rats with myocardial infarction (MI). Firstly, male Wistar rats were exposed to LAD coronary artery ligation surgery and then echocardiography confirmed creation of MI. 4 weeks after surgery, the rats with MI were divided randomly into 4 groups: low intensity training (LIT), moderate intensity training (MIT), high intensity training (HIT), and sham, plus a healthy control group (Con). Training groups performed training exercise protocols for 6 weeks, 5 sessions per week. The results of one-way ANOVA showed significant differences in ejection fraction (EF), fractional shortening (FS), left ventricular internal diameter end diastole (LVIDd) and end systole (LVIDs) among all groups (P≤0.05). LSD post hoc test results demonstrated that ejection fraction in the 3 training exercise groups and fractional shortening in MIT and HIT groups increased significantly compared with the sham group. However, their values in the MI groups were significantly lower than the Con group (P≤0.05). LVIDd values in the HIT group significantly increased compared with the Con, sham and MIT groups and also in LIT group compared with Con group. Also, LVIDs values in MI groups were significantly higher than Con group (P≤0.05). In conclusion, training exercise, regardless the intensity, improves left ventricular structure and function. However, it seems that higher intensities of training exercise have more drastic effects on left ventricular function in rats with MI.