Effects of exercise intensity on soleus muscle myostatin and follistatin levels of hyperglycaemic rats

Background: Hyperglycaemia induces dysregulations in skeletal muscle mass and function. Myostatin (Mstn) and follistatin (Fs) are two key regulators of muscle mass, which are known to be dysregulated in people with hyperglycaemia. Exercise is frequently prescribed to counteract these changes; however, the influence of exercise intensity is unknown.The purpose of this study was to compare two training programs, moderate-intensity constant (MICT) and high-intensity interval training (HIIT), on soleus mRNA levels of Mstn and Fs in an animal model of hyperglycaemia. Material and Methods: 36 maleWistar rats, were divided into control (n=18) and hyperglycaemic (HG, n=18; induced by a single intraperitoneal dose of Streptozotocin) groups. Subsequently, these groups were randomly subdivided into control untrained,control+moderate-intensity constant training (MICT), control+high-intensity interval training (HIIT),HG untrained,HG+MICT, and HG+HIIT (n=6 each subgroup).Training programs were performed for 8 weeks, with a frequency of 5 sessions per week.The total distance covered per session in MICT and HIIT was equal. 48 hours following the last training session, rats were anesthetized and soleusmuscles were excised. Results: HIIT reduced and increased significantly the Mstn and Fs mRNA levels respectively, irrespective of hyperglycaemia (p<0.05).When Mstn:Fs ratio was analysed, only HIIT induced a significant increase in hyperglycaemic rats (p<0.05). Conclusion: HIIT over MICT, changed the Mstn and Fs soleus mRNA levels, irrespective of hyperglycaemia.This could indicate that the regulation of these genes is exercise intensity-dependent, whereas hyperglycaemia seems to not blunt this response.