Exercise improves muscle insulin resistance without lowering key growth signals in high-fat diet rats

Six weeks of exercise improved glucose tolerance and insulin response in skeletal muscles of rats on a high-fat diet.

• Exercise enhanced insulin-stimulated glucose uptake in both soleus and extensor digitorum longus muscles.
• High-fat diet reduced type I fiber ratio in soleus and increased it in extensor digitorum longus, while also decreasing fiber size in extensor digitorum longus.
• Exercise increased type I fiber ratio and cross-sectional areas in extensor digitorum longus and soleus muscles.
• High-fat diet affected basal phosphorylation of S6K1 in soleus, with exercise interactions noted in extensor digitorum longus.
• Exercise prevented the high-fat diet-induced decrease in basal phosphorylation of S6K1 in extensor digitorum longus.

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