The Effect of High- and Low-Intensity Interval Training on Myostatin Gene Expression Levels in Muscles Fibers of Rats with Myocardial Infarction

Introduction: Myocardial infarction (MI) is an essential coronary artery disease, which affects mitochondrial function and causes muscle atrophy due to vessel blockage and disruption in blood transfusion and oxygen transfer. Interval exercises reduce muscle atrophy, but the appropriate exercise intensity is still unknown. This study aimed to evaluate the effect of interval training with two for six weeks on Myostatin gene expression levels in slow (ST) and fast (FT) twitch muscles in rats with MI. Method: Eighteen ten-week male Wistar rats with MI were randomly assigned into high- (HIIT) (90-85% VO2max) and low-intensity interval training (LIIT) (50-60% VO2max) with a control group (CG, without training). Myostatin gene expression of FT and ST was investigated as a stimulant of muscle atrophy. The training protocol was 30-minute intermittent jogging sessions on a treadmill. Each interval included 4 min of running (85-90% VO2max for HIIT and 55-60% for LIIT) and 2-minute active recovery (50-60% for HIIT and 45-50% for LIIT) three days a week for six weeks. Results: LIIT significantly decreased myostatin expression in both ST and FT while HIIT only decreased myostatin expression in ST compared to CG (P = 0.002, P = 0.016, and P=0.011, respectively). HIIT induced myostatin expression reduction was higher in FT compared to CG (P = 0.078). There was a significant difference in myostatin expression between CG (8.87) and the two training groups (HIIT [0.949] and LIIT [3.11]) in ST (P≤0.05), and between  CG and LIITs and HIIT (1.22) and LIIT (0/975) in FT (P 0.05). Conclusion: Six weeks of HIIT and LIIT reduced myostatin gene expression and decreased ST and FT atrophy in rats with MI.