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Background and Objective: Sphingosine-1-phosphate (S1P) is involved in regulation of proliferation, differentiation, hypertrophy and anti-apoptosis and activation of satellite cells. This study was done to evaluated the effect of 8 weeks resistance training on sphingosine-1-phosphate level and gene expression of SK1 enzyme, isoforms of MHCs in skeletal muscles of male Wistar rats. Materials and Methods: This experimental study was done on Twenty four 8-week-old 190-250 gr male Wistar rats. The rats were allocated randomly into control (N=12) and training (N=12) groups. Resistance training was done using a 1 meter height ladder with 2 cm grid with an 85 degree incline, and weights attached to rat's tails. The content of S1P present in the chloroform layer was determined by means of high performance liquid chromatography (HPLC). Determination of relative mRNA expression was performed by Real-time PCR. Data were analyzed using SPSS-17, Kolmogorov-Smirnov and independent t-test. Results: Resistance exercise training increased the total content of S1P in FHL (fast-twitch) and soleus (slow-twitch) muscles in comparison with control group (P<0.05). Resistance exercise training changed the gene expression of FHL SK1, SOL SK1, FHL MHC I, Sol MHC I, FHL MHC IIa, Sol MHC IIa, FHL MHC IIb, Sol MHC IIb, FHL MHC IIx, Sol MHC IIx in comparison with control group (P<0.05). Conclusion: This study showed that S1P level and gene expression of SK1, MHCs increased at skeletal muscles after training.

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Background and Objective: Sphingosine-1-phosphate (S1P) plays an important role in muscle biology and is involved in hypertrophy and activation of satellite cells. This study was done to determine the effect of eight weeks of concurrent training with different order on S1P in fast and slow muscles in wistar rats.
Methods: In this experimental study, 40 male wistar rats (weight 180-200 gr) were randomly allocated into 5 groups including control, resistance training, endurance training, resistance- endurance training, endurance- resistance training. Resistance training consisted 1-meter ladder climbing with the loading of percent of overloading test (%75 of weight body) in the first week and increased to 30 gr per week. Endurance training consisted of running on treadmill with speed of 12 m/min and 10 minutes in the first week to 30 m/min and 60 minutes in the last week. The resistance- endurance group performed resistance training 5 minutes before endurance training and the endurance- resistance group performed endurance training 5 minutes after resistance training. The protein level of S1P was measured in flexor hallucis longus (FHL) and soleus muscles.
Results: The S1P level in fast and slow twitch muscle increased significantly in endurance- resistance training, resistance- endurance training and resistance training compared to controls (P<0.05). There were no significant differences between concurrent training with differing order.
Conclusion: It seems that exercise order in concurrent training result in no different effect on S1P level in fast and slow twitch muscles in wistar rats.