Comparison of the effects of high-intensity interval training and moderate-intensity continuous training on indices of liver and muscle tissue in high-fat diet-induced male rats with non-alcoholic fatty liver disease

Background Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases. It is shown that moderate to high physical activities can play a crucial role in improving this disease. Aim The purpose of this study was to explore the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on the levels of the myonectin in serum and tissue levels and fatty acid transport protein 4 (FATP4) in male rats with NAFLD. Materials and methods Thirty-three male rats were randomly divided into five groups: high-fat diet to confirm NAFLD induction ( n = 5), normal diet sedentary ( n = 7), high-fat diet sedentary ( n = 7), high-fat diet with HIIT ( n = 7), and high-fat diet with MCIT ( n = 7). Induction of NAFLD was performed by feeding rats for 12 weeks with a high-fat diet containing 60% fat. The training protocols were performed in five sessions per week for 8 weeks. The HIIT group has performed 4 × 4 min interval running on a treadmill up to 80–95% maximal oxygen uptake (VO2max) and then recovered at 50–60% VO2max. The MICT protocol has performed up to 50–60% VO2max for 50 min. myonectin and FATP4 were also measured by the animal Elisa kit (Zellbio, Germany) with a sensitivity of 0.02 ng/L. Insulin resistance was evaluated by the insulin resistance homeostasis assessment index using the following formula (HOMA-IR): “fasting glucose (mg/dl) × fasting in insulin (mg/L) ÷ 405”. One-way ANOVA analysis of variance was utilized for statistical analyses and Tukey’s post hoc test at a significant level of p < 0.05. Results The 8-week intervention showed that both HIIT and MICT positively influenced the serum myonectin and FATP4 levels ( p < 0.05). Moreover, there was a significant difference between the trained groups in tissue levels of the myonectin and serum levels of FATP4 ( p < 0.05). Conclusions Altogether, both HIIT and MICT can lead to valuable adaptations and recovery of NAFLD in male rats.