Background: It is known that irisin plays a role in regulating energy balance and body weight. Hence, the aim of this study was to evaluate the effects two models of high intensity interval training and moderate intensity continuous training on the irisin serum and peroxisome-proliferator-activated receptor co-activator-1α (PGC-1α) gene expression in skeletal muscle tissue of male rats.
Methods: This experimental study was conducted in Baqiyatallah University of Medical Sciences during the summer months of 2016. In this study, 32 male Wistar rats (mean weight =250±55 g, age: 8 weeks) were randomly and equally were divided in to 4 groups: basic control (CO), control of eight weeks (CO8w), moderate intensity continuous training (MICT) and high intensity interval training (HIIT). CO group rats at baseline were killed and CO8w group was held concurrently with the experimental group but did not participate in any exercise training. HIIT and MIET groups for 8 weeks also did moderate continuous training (15-60 minute at 15-30 m/min) and sever intensity continuous training (4-8 one-minute intense interval of 28-58 m/min, with a 3-7 one-minute slow interval of 28-58 m/min). The enzyme-linked immunosorbent assay (ELISA) method for measuring serum irisin levels and real-time PCR method for the relative expression of mRNA of PGC-1α gene were used. The data were analyzed by one-way analysis of variance (ANOVA) and Tukey's post-hoc test at P<0.05 level. All analyzes were performed using SPSS software, version 21 (SPSS Inc., Chicago, IL, USA).

Conclusion: The results show that the two methods of exercise training may be the upstream pathway's activation can increase transcription of the PGC-1α gene (a key regulator of energy metabolism and mitochondrial biogenesis) in skeletal muscle, but doesn't make a significant change in the levels of serum irisin.