Abstract

Introduction: The aim of this study was to investigate the effect of moderate intensity continuous training on necrosis and fibrosis of cardiac tissue and their mechanisms in male rats with myocardial infarction.

Methods: Thirty wistar rats weighing 180 g-230 g and in the age range of 2-3 months were randomly divided into three groups: Healthy control, control with myocardial infarction and training group with myocardial infarction. The rats in the training group ran on a treadmill with a zero degree slope 5 days a week for 8 weeks. The training started at a speed of 16, which increased to 2 meters per minute after two weeks or 0.2 meters per second per training session. 48 hours after the last exercise session, the rats were sacrificed and their hearts were removed. Necrotic damage, fibrosis rate, HMGB1, TLR4, TNF-α and collagen type I protein levels were measured.

Findings: The results showed that with myocardial infarction, the levels of HMGB1, TLR4, TNF-α, Col I, the rate of fibrosis and necrotic damage increased significantly (P<0.05), but training significantly reduced all these variables (P<0.05). After training, HMGB1, TLR4 and fibrosis rate were still significantly higher than pre-myocardial infarction values (P<0.05) but TNF-α, Col I and necrotic damage were not significantly different from pre myocardial infarction values (P>0.05).

Conclusion: Although myocardial infarction increases inflammation and damage to cardiac tissue, moderate intensity aerobic training may be able to reduce the amount of inflammation and damage to cardiac tissue after a myocardial infarction.

Keywords: Exercise training, Inflammation, Cardiac necrosis, Cardiac fibrosis, Myocardial infarction