en Sports and Exercise Medicine Sports and Exercise Medicine Original Research Original Research <strong>Background: </strong>Altered circulating amino acids levels have been observed in metabolic disorders, like obesity, type-2 diabetes, and other insulin-resistant states. This study aimed to investigate the effect of 8-week walking on plasma amino acids (PAAs) in obese girls.<br> &nbsp;&nbsp; <strong>Methods:</strong> This clinical trial study (IRCT20180928041160N1) was conducted on 32 early/mid pubertal obese girls which they divided into interval-walking (IWG, n=12), continuous-walking (CWG, n=11) and control (CG, n=9) groups. The walking program (3-sessions/week for 8-weeks) consists of 30-min walking with 70-85%HRmax and 60-75%HRmax, respectively in the IWG (2-min walking and 1-min active rest) and CWG. The concentration of PAAs was measured at baseline and 72-hours after the last session in fasting state, using high-performance liquid chromatography. A repeated measures ANCOVA (group (3) * time (2)) with post hoc Bonferroni was used to analyze the data.<br> &nbsp;&nbsp; <strong>Results:</strong> More the PAAs were not affected by interval or continuous walking training. A significant increase in lysine (p=0.003, 95%CI 24.08, 108.97) was observed only in the CG, and there was a significant difference between the CG and CWG (p=0.032). Global arginine bioavailability (GABA) significantly decreased in the CG (P<0.001, 95%CI -0.65, -0.21) and the IWG (p=0.004, 95%CI -0.60, -0.21). A significant increase in weight (p=0.043, 95%CI 0.27, 1.46), insulin (p=0.046, 95%CI -0.91, 9.01), and HOMA-IR (p=0.007, 95%CI 0.26, 2.63) were found only in the CG, and both insulin and HOMA-IR tended to decline in the CWG.<br> &nbsp;&nbsp; <strong>Conclusion:</strong> Except for lysine and GABA, all groups roughly showed similar changes in more amino acids. Continuous-walking could improve the plasma level of lysine and GABA, which along with an improvement of fasting insulin levels and HOMA-IR. Obesity, Child, Puberty, Walking, Amino acids 768 777 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-4742-1&slc_lang=en&sid=1 Masoumeh Baghersalimi baghersalimi.m@gmail.com 200319475328460062298 200319475328460062298 No Department of Exercise Physiology, Faculty of Sport Sciences, University of Mazandaran, Babolsar, Iran Rozita Fathi r.fathi@umz.ac.ir 200319475328460062299 200319475328460062299 Yes Department of Exercise Physiology, Faculty of Sport Sciences, University of Mazandaran, Babolsar, Iran Sohrab Kazemi kazemi.msm@gmail.com 200319475328460062300 200319475328460062300 No Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran