Training-induced improvement in lipid oxidation in type 2 diabetes mellitus is related to alterations in muscle mitochondrial activity. Effect of endurance training in type 2 diabetes.

AIM We investigated whether or not, in type 2 diabetic (T2D) patients, an individualized training effect on whole-body lipid oxidation would be associated with changes in muscle oxidative capacity. METHODS Eleven T2D patients participated in the study. Whole-body lipid oxidation during exercise was assessed by indirect calorimetry during graded exercise. Blood samples for measuring blood glucose and free fatty acids during exercise, and muscle oxidative capacity measured from skeletal muscle biopsy (mitochondrial respiration and citrate synthase activity), were investigated in the patients before and after a 10-week individualized training program targeted at LIPOXmax, corresponding to the power at which the highest rate of lipids is oxidized (lipid oxidation at LIPOXmax). RESULTS Training induced both a shift to a higher-power intensity of LIPOXmax (+9.1+/-4.2W; P<0.05) and an improvement of lipid oxidation at LIPOXmax (+51.27+/-17.93 mg min(-1); P<0.05). The improvement in lipid oxidation was correlated with training-induced improvement in mitochondrial respiration (r=0.78; P<0.01) and citrate synthase activity (r=0.63; P<0.05). CONCLUSION This study shows that a moderate training protocol targeted at the LIPOXmax in T2D patients improves their ability to oxidize lipids during exercise, and that this improvement is associated with enhanced muscle oxidative capacity.