High-fat diet impairs the effects of a single bout of endurance exercise on glucose transport and insulin sensitivity in rat skeletal muscle.

A single bout of exercise increases the rate of muscle glucose transport (GT) by both insulin-independent and insulin-dependent mechanisms. The purpose of this study was to determine whether high-fat diet (HFD) feeding interferes with the metabolic activation induced by moderate-intensity endurance exercise. Rats were fed an HFD or control diet (CD) for 4 weeks and then exercised on a treadmill for 1 hour (19 m/min, 15% incline). Insulin-independent GT was markedly higher in soleus muscle dissected immediately after exercise than in muscle dissected from sedentary rats in both dietary groups, but insulin-independent GT was 25% lower in HFD-fed than in CD-fed rats. Insulin-dependent GT in the presence of submaximally effective concentration of insulin (0.9 nmol/L) was also higher in both dietary groups in muscle dissected 2 hours after exercise, but was 25% lower in HFD-fed than in CD-fed rats. Exercise-induced activation of 5'adenosine monophosphate-activated protein kinase, a signaling intermediary leading to insulin-independent GT and regulating insulin sensitivity, was correspondingly blunted in the HFD group. High-fat diet did not affect glucose transporter 4 content or insulin-stimulated Akt phosphorylation. Our findings provide evidence that an HFD impairs the effects of short-term endurance exercise on glucose metabolism and that exercise does not fully compensate for HFD-induced insulin resistance in skeletal muscle. Although the underlying mechanism is unclear, reduced 5'adenosine monophosphate-activated protein kinase activation during exercise may play a role.