The aim of this study was to determine the effect of Quercetin supplement during sedentary period on the signaling pathway of the PGC-1α. Researchers are trying to find out whether Quercetin supplement consumption can be beneficial to preventing atrophy during sedentary period. In this study, 30 male rats (age=2 months old, weight=295±11.80 g, Sprague-Dawley) were selected. They were assigned to 2 groups: control (n=6) and training (n=24). Interval training with the intensity of 16 m started in the first week and reached the speed of 30 m/min. in the eighth week. Then, the rats of the control group and 6 rats of the training group were killed. Then, the rest of training group (n=18) were randomly divided into 3 groups: detraining, sedentation and sedentation-Quercetin supplement. Sedentary groups became inactive for 14 days and Quercetin supplement group was fed with Quercetin (400 mg/day) during this period. After these 14 days, they were killed and the amount of the PGC-1α gene expression of their soleus muscle was measured. The mean weight of the rats was higher than the control and the other two groups (detraining and sedentation) (P=0.001). On the other hand, after 14 days, the sedentation-Quercetin group had the highest whereas the sedentation group had the lowest amount of PGC-1α gene expression (P=0.004). The results of the changes showed that the minimum reduction in the muscle weight and gene expression of the PGC1α during sedentary period can be expected by consuming Quercetin supplement.