Effect of prior exercise on glucose metabolism in trained men

Several studies have demonstrated that oral glucose tolerance is impaired i n the immediate postexercise period. A double-tracer technique was used to examine glucose kinetics during a 2-h oral glucose (75 g) tolerance test (O GTT) 30 min after exercise (Ex, 55 min at 71 +/- 2% of peak O-2 uptake) and 24 h after exercise (Rest) in endurance-trained men. The area under the pl asma glucose curve was 71% greater in Ex than in Rest, (P = 0.01). The high er glucose response occurred even though whole body rate of glucose disappe arance was 24% higher after exercise(P = 0.04, main effect). Whole body rat e of glucose appearance was 25% higher after exercise (P = 0.03, main effec t). There were no differences in total (2 h) endogenous glucose appearance (RaE) or the magnitude of suppression of RE, although RaE, was higher from 15 to 30 min during the OGTT in Ex. However, the cumulative appearance of o ral glucose was 30% higher in Ex (P = 0.03, main effect). There were no dif ferences in glucose clearance rate or plasma insulin responses between the two conditions. These results suggest that adaptations in splanchnic tissue s by prior exercise facilitate greater glucose output from the splanchnic r egion after glucose ingestion, resulting in a greater glycemic response and , consequently, a greater rate of whole body glucose uptake.