EFFECT OF AN ACUTE BOUT OF EXERCISE ON GLUCOSE DISPOSAL IN HUMAN OBESITY

The effect of acute exercise on insulin action has been studied in six obese (150-250% ideal body weight) non-insulin-dependent diabetics (OD), seven obese normoglycemics (ON), and six lean healthy controls (LC). Using a three-stage euglycemic clamp, the metabolic clearance rate (MCR) of glucose under increasing concentrations was measured. The insulin dose-response curve was assessed on two separate occasions: 1) a base-line test and 2) 1 h after aerobic treadmill exercise at a steady-state heart rate of 150-160 beats/min. In the base-line test, under all insulin levels, glucose MCR was significantly lower in obese compared with lean individuals (P < 0.01). Exercise increased glucose MCR at the highest hormonal concentrations applied to 124 and 134% of base line in OD and in ON, respectively (P < 0.05); the insulin concentration required for one-half of the maximal clearance rate of glucose achieved in this study decreased from 200 to 130 and from 160 to 95 μU/ml in OD and ON, respectively (P < 0.05. The changes in these parameters were insignificant in LC. It is suggested that acute exercise affected the insulin dose-response curve in OD and in ON but not in LC; although enhanced by exercise, glucose MCR remained significantly lower in both obese groups compared with control subjects. We concluded that insulin resistance, with accompanies extreme obesity, could be markedly decreased but not completely reversed by one bout of exercise.