Morphological aspects of the heart of young rats subjected to high and medium intensity progressive resistance physical exercise protocols

The present study investigated the effects of medium and high intensity physical exercise on the morphology of the heart of young rats, after carrying out two physical exercise protocols on the stairs, medium and high intensity. We used 24 young male Wistar rats, 21 days old, divided into three groups: sedentary control group (CG, n=8), group trained with medium intensity physical exercises (GM, n=8) and group trained with physical exercises high intensity (GA, n=8). For 4 weeks, the animals in the GM and GA groups were subjected to a medium and high intensity physical exercise protocol. The physical exercise protocol was applied over a period of 4 weeks, 5 days a week. After training, the animals were euthanized and the heart was removed for weighing, analysis of macroscopic morphology (left ventricular thickness, weight, analysis of diameter and ventricular area); The 5um sections were then processed and stained with Hematoxylin and Eosin (HE) for subsequent histomorphometric analysis of the cardiomyocytes. The results did not demonstrate significant differences in the macroscopic parameters of the heart (weight, left ventricular thickness, ventricular area, total area, ventricular diameter). A significant difference was observed in the area of cardiomyocytes in the left ventricle of rats that exercised with high intensity. It is concluded that rats exercising at high intensity showed an increase in the area of cardiomyocytes compared to rats that exercised at medium intensity and sedentary ones. Thus, it is concluded that progressive resistance physical exercise on the vertical ladder when performed at high intensity promotes cardiomyocyte hypertrophy in young rats.