The aim of this study was to investigate the effect of resistance training with different intensities on serum myostatin and follistatin levels in sedentary young women. Materials and Methods: In this practical and semi experimental study, 24 sedentary young women with range of 20-30 years and BMI 22-25 kg/m 2 were selected by convenience sampling. Then, the volunteers were randomly assigned into two groups, [resistance training group with low intensity (40-60% of one repetition maximum) and

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... h intensity (70-90% of one repetition maximum)]. The training protocols included: 8 weeks, 3 times a week. Blood samples (5cc) were obtained at baseline and 48 hours after at the end of the study; Also Serum levels of myostatin and follistatin were measured by ELISA methods. Data were analyzed using analysis of variance of repeated measures test by SPSS at the significant level (p<0.05). Results: There was a significant increase in the levels of follistatin and follistatin to myostatin ratio in high intensity group (p≤0.05). Also there was a significant decrease in the levels of myostatin in high intensity group (p≤0.05); however, there was no significant change in the levels of follistatin, myostatin and follistatin to myostatin ratio in low intensity group (p≥0.05). Also there was no significant change in these variables in high intensity group compared to low intensity group (p≥0.05). Conclusion: It's seems that the activation of important myogenic and myostatic factors in sedentary young women need to do high intensity resistance training.