Chronic obesity and insulin resistance are considered to inhibit contraction-induced muscle hypertrophy, through impairment of mTORC1 and muscle protein synthesis (MPS). A high-fat diet is known to rapidly induce obesity and insulin resistance within a month. However, the influence of a short-term high-fat diet on the response of mTORC1 activation and MPS to acute resistance exercise (RE) is unclear. Thus, the purpose of this study was to investigate the effect of a short-term high-fat diet on the response of mTORC1 activation and MPS to acute RE. Male Sprague-Dawley rats were randomly assigned to groups and fed a normal diet (ND), high-fat diet (HFD 4wk), or pair feed (PF 4wk) for 4 weeks. After dietary habituation, acute RE was performed on the gastrocnemius muscle via percutaneous electrical stimulation. The results showed that 4 weeks of a high fat-diet induced intramuscular lipid accumulation and insulin resistance, without affecting basal mTORC1 activity or MPS. The response of RE-induced mTORC1 activation and MPS was not altered by a high-fat diet. On the other hand, analysis of each fiber type demonstrated that response of MPS to an acute RE was disappeared specifically in type I and IIa fiber. These results indicate that a short-term high-fat diet causes anabolic resistance to acute RE, depending on the fiber type.
Aerobic versus resistance exercise training in modulation of insulin resistance, adipocytokines and inflammatory cytokine levels in obese type 2 diabetic patients