The Effects of High Intensity Interval Training (HIIT), Endurance Training and Resistance Training on Serum Insulin-Like Growth Factor-1 Level, miRNA-133a and miRNA-1 Expression and Physical Performance in Male Athletes

The aim of this study was to investigate the effect of eight weeks of high intensity interval training (HIIT), endurance training and resistance training on aerobic fitness (VO2max), maximal strength, insulin-like growth factor-1 (IGF-1), the expression of miRNA-1 and miRNA-133a in young male athletes. In this semi-experimental study, 49 young male athletes (18-20 years old) were selected and randomly assigned to four equal groups: HIIT, endurance training (EN), resistance training (RES) and control. Then, eight weeks (3 to 4 sessions per week) of HIIT, endurance training and resistance training were performed. Blood samples were collected 24 hours before and after the training intervention. miRNA-1 and miRNA-133a expressions decreased after three types of training (P<0.05). Also, there was no significant difference among the three groups (P>0.05). VO2max significantly increased after 8 weeks of HIIT and RES training. This increase in HIIT group was significantly higher than the other three groups. Concentration of IGF-1 increased significantly after the intervention in the EN and HIIT groups. In addition, the bench press increased only in the RES group and leg press and lean body mass (LBM) increased in all three training groups; this increase in the RES group was more than the EN and HIIT groups. It seems that these miRNAs are circulation biomarkers to evaluate adaptation to training.