en بهداشت Health تحقیقی Original article <span style="font-size:12px;"><span style="font-family:Times New Roman;"><b>Background:</b> Metabolic syndrome, a problem of the present age, is a combination of several medical issues, and miRNAs play important regulatory roles in metabolic syndrome. Many studies indicate that high-intensity interval training (HITT) may improve risk factors for metabolic syndrome.<br> This study aimed to investigate the effect of 8 weeks of HIIT training on the changes in miR-21, miR-122, alanine aminotransferase (ALT), aspartate aminotransferase (AST), low-density lipoprotein (LDL), lipid profile, and glucose.<br> <b>Methods:</b> In this quasi-experimental study, middle-aged male (n=19) volunteers with metabolic syndrome (body mass index (BMI)>30) were randomly assigned to the control (n=9) and training (n=10) groups. The training program consisted of 8 weeks of HIIT training with 4 sets of workouts with an intensity of 80-90% heart rate for the training group (3 sessions per week during the first 4 weeks and 4 sessions per week during the second 4 weeks). Blood samples were collected from the subjects 48 hours before and after the last training session to analyze miR-21, miR-122, ALT, AST, HDL, LDL, triglyceride, cholesterol, and glucose. The within-group and between-group differences of data were analyzed using the paired t-tests and analysis of covariance at a significance level of P˂0.05 in SPSS software.<br> <b>Results:</b> This study indicated that HIIT caused a significant decrease in miR-122, ALT, AST, triglyceride, cholesterol, glucose, body weight indicators, fat percentage, and BMI (P˂0.05). Also, a significant increase in miR-21 and HDL levels was observed following HIIT training (P˂0.05).<br> <b>Conclusion</b>: HIIT training seems essential in metabolic changes, such as reducing the lipid profile, decreasing glucose, and improving liver damage by affecting miR-21 and miR-122 indicators as small regulatory transcripts. However, more extensive studies are needed in this field.</span></span><br> &nbsp; High-intensity interval training,MIRN21 microRNA, human,MIRN122 microRNA, human,Metabolic syndrome, 25 29 http://goums.ac.ir/jorjanijournal/browse.php?a_code=A-10-962-1&slc_lang=en&sid=1 Hamid Reza Zolfi 10031947532846009326 10031947532846009326 No Department of Physical Education and Sport Science, Technical and Vocational University (TVU), Tehran, Iran Amir Shakib 10031947532846009327 10031947532846009327 No Faculty of Physical Education and Sport Sciences, University of Tabriz, Tabriz, Iran Zahra Niknam gloryofleaves61@yahoo.com 10031947532846009328 10031947532846009328 No Faculty of Physical Education and Sport Sciences, University of Tabriz, Tabriz, Iran zhaleh pashaei pashaei.zh@gmail.com 10031947532846009329 10031947532846009329 Yes Faculty of Physical Education and Sport Sciences, University of Tabriz, Tabriz, Iran