Two treatments that increase skeletal muscle
insulin action are exercise training and high-
carbohydrate diet. The purpose of the present study was to determine whether exercise training and a diet high in
carbohydrates could function synergistically to reduce the muscle
insulin resistance in the obese Zucker rat. Obese rats 4 wk of age were randomly assigned to an exercise or sedentary group. Each group was subdivided by diet with one-half of the rats fed a high-
carbohydrate diet and one-half fed a high-fat diet. Lean Zucker rats fed the high-fat diet were used as controls. Muscle
insulin resistance was assessed during hindlimb perfusion with a submaximally stimulating concentration of
insulin. Exercise training and the high-
carbohydrate diet increased the rate of muscle
glucose uptake in the obese rat by 46 and 53%, respectively. More importantly, the combined effect of exercise training and high-
carbohydrate diet was greater than the sum of their individual effects.
Glycogen synthesis paralleled
glucose uptake and was the major pathway for intracellular
glucose disposal. Muscle
glucose uptake for exercise-trained, high-
carbohydrate fed obese rats was comparable with that of lean controls. It is concluded that exercise training and the high-
carbohydrate diet functioned synergistically to reduce the muscle
insulin resistance in the obese rat.