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Background and Objective: The synthesis of uncoupling protein 1 (UCP1) in adipose tissue plays an important role in providing resistance and prevention of fat accumulation, weight gain and obesity. This study was done to evaluate the effect of eight weeks aerobic training with moderate and high intensities on serum levels of Irisin and UCP1 white adipose tissue in obese male rats.
Methods: In this experimental study, 24 adult obese male Wistar rats (weight: 250 to 300 gr, BMI>30g/cm²) were randomly assigned into three groups including moderate aerobic training intensity, high intensity aerobic training and control group. The aerobic exercise training was included 8 weeks (5 sessions/per-week for 60 min per session). All training groups carried out aerobic training with 28 m/min (moderate intensity), aerobic training with 34 m/min (high intensity) on treadmill. 48 hours after the training period, the level of UCP1 and Irisin protein was measured.
Results: The level of UCP-1 in adipose tissue and serum Irisin in both aerobic training intensities increased compared to control group, but this increase only in aerobic training group with a moderate intensity was singnificant (p<0.05).
Conclusion: Eight weeks aerobic training with moderate intensity leads to increase of UCP-1 in adipose tissue and Irisin levels.

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Background and Objective: Increasing the cost of energy in obesity preventing and treating and reducing its complications can be achieved by stimulating the factors including Irisin and FGF21 associated with browning of the white adipose tissue. The aim of this study was to determine the effect of 12 weeks of light and heavy interval exercises on the level of irisin and FGF21 in obese and overweight women.
Methods: This clinical traial study was done on 35 overweight and obese women (39.8±3.85 years old and body mass index 27.1±3.37 kg/m²). The subjects were divided randomly into three groups of interval exercises including Heavy (n=12), light (n=12), and control (n=11) groups. The training program included 12 weeks of heavy and light interval exercises for 25 to 60 minutes per session and three sessions per week. Before and after the training period, irisin and FGF21 serum indices were measured for each subject.
Results: Serum level of FGF21 increased only after 12 weeks of heavy interval training (P<0.05). However, there was no change in serum irisin levels after both heavy and light interval exercises. Body fat percentage, waist to hip ratio, and BMI Subjects of light and heavy interval exercises reduced and VO₂max increased significantly compared to control group (P<0.05).
Conclusion: 12 weeks of low and heavy interval training without altering serum levels of irisin have a beneficial effect on increasing VO₂max and improving body composition. Also, heavy interval training has a significant increase in FGF21, Which can be effective in weight loss through the browning of white adipose tissue.