Abstract des Autors

The effects of a single bout of exercise on glucose effectiveness (SG) and insulin sensitivity (SI) in 22 sedentary subjects were estimated with a minimal model approach. The intravenous glucose tolerance test (IVGTT) was performed 1) 11 h after an exercise bout on a cycle ergometer at the lactate threshold level (mild exercise) for 60 min, 2) 11 h after an exercise bout at the 4 mM lactate level (hard exercise) for 36+/-1 min, 3) 11 h after an exhaustive-exercise bout (exhaustive exercise) for 96+/-7 min, or 4) without any prior exercise (control). Only the exhaustive exercise increased the glucose disappearance constant and SI in comparison with the control condition. The SG and SG at zero insulin (GEZI) were not affected by any exercise condition. However, a marked individual difference in GEZI emerged after the exhaustive exercise and could be divided into two subgroups: one decreased in GEZI and the other increased in GEZI. The former subgroup was accompanied by elevated levels of plasma creatine kinase and myoglobin, whereas the latter subgroup showed no significant change in creatine kinase. In both subgroups, SI was similarly increased after the exhaustive exercise. These results thus suggest that a single bout of exercise that results in muscle damage or changes in muscle permeability, as reflected in the increased creatine kinase and Mb levels, decreases GEZI, whereas exhaustive exercise without such alterations increases GEZI. Verf.-Referat