Prolonged Exercise-Induced Stimulation of Skeletal Muscle Glucose Uptake Is due to Sustained Increases in Tissue Perfusion and Fractional Glucose Extraction

• Context: The mechanisms behind the positive effects of physical activity on glucose metabolism in skeletal muscle and the time course of the effects need to be more elucidated. Objective: The aim was to examine the prolonged effects of an acute bout of one-legged exercise on local skeletal muscle glucose utilization and tissue perfusion. Design and Setting: Interstitial glucose concentration, local tissue perfusion, glucose uptake, and effects of insulin infusion were studied 12 h after an acute bout of exercise and without prior exercise. Participants: Ten healthy subjects, five women and five men, participated in the study. Intervention: Microdialysis measurements, (133)Xe clearance, and a 2-h hyperinsulinemic euglycemic clamp were performed on two occasions. Main Outcome Measures: We measured interstitial glucose concentration and tissue perfusion in the quadriceps femoris muscle of both legs. Results: Tissue perfusion (3.3 +/- 0.6 ml x 100 g(-1) x min(-1) vs. 1.4 +/- 0.2 ml x 100 g(-1) x min(-1); P = 0.007) and basal glucose uptake (2.3 +/- 0.5 mu mol x 100 g(-1) x min(-1) vs. 0.9 +/- 0.2 mu mol x 100 g(-1) x min(-1); P = 0.006) were increased in the leg that had exercised compared to the resting leg; the findings in the resting leg were comparable to those in the control experiment without prior exercise. The relative effect of insulin on fractional skeletal muscle glucose uptake was the same in all experimental settings, and insulin did not affect tissue perfusion. Conclusions: The prolonged stimulatory effect of physical exercise on skeletal muscle glucose uptake was mediated via vascular effects combined with an increase in basal glucose transport independent of enhancement of insulin responses.

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