Prolonged increase in insulin-stimulated glucose transport in muscle after exercise

Abstract

Exercise can induce short-term increases in the sensitivity and responsiveness of skeletal muscle glucose transport to insulin. The purpose of this study was to determine the effect of carbohydrate deprivation on the persistence of increased insulin sensitivity and responsiveness after a bout of exercise. Three hours after a bout of exercise, epitrochlearis muscles from carbohydrate-deprived (fat fed) rats showed a 25% greater increase in 3-O-methylglucose (3-MG) transport in response to a maximal insulin stimulus compared with muscles of nonexercised rats; this increase in insulin responsiveness had reversed 18 h postexercise. Muscles of rats fed carbohydrate showed no increase in insulin responsiveness 3 h after exercise. The effect of 60 microU/ml of insulin on 3-MG transport was approximately twofold greater in muscles studied 3 h after exercise than in nonexercised controls regardless of dietary carbohydrate intake. This increase in insulin sensitivity was lost within 18 h in carbohydrate-fed rats but persisted for at least 48 h in carbohydrate-deprived rats. Muscle glycogen increased approximately 41 mumol/g in the rats fed carbohydrate for 18 h, and only approximately 14.5 mumol/g in the rats fed fat for 48 h, after exercise. The persistent increase in insulin sensitivity after exercise in carbohydrate-deprived rats was unrelated to caloric intake, as muscles of fasted and fat-fed rats behaved similarly.

Acute exercise increases insulin sensitivity in adult sheep: a new preclinical model

“…This is consistent with previous reports of increased whole body or skeletal muscle insulin sensitivity persisting for 4 -48 h after a single bout of exercise in humans (34,46,54) and 4 -48 h after acute exercise in rodents (8,18,44). This is the first report of exercise-induced increases in insulin sensitivity in a nonhuman large animal.…”

“…Previous studies in humans and rodents have reported increased insulin sensitivity after either higher-intensity or longer-duration acute exercise protocols than used in the present study (3,8,15,19,23,34,43,44,54). The exercise intensity achieved in the present study by sheep in the intensive exercise test (30 min, 8% slope, 4 -4.4 km/h) is probably ϳ50 -60% of V O 2max , based on studies in pregnant sheep (26).…”

“…Importantly, a single bout of exercise also increases the insulin sensitivity of glucose uptake during the following 4 -48 h in healthy humans (34,46,52,54,55). Similar effects have been demonstrated in rodents, where an acute exercise bout increases in vitro insulin-stimulated glucose uptake in mouse muscle 85 min after exercise (18) and in rat muscle collected 3-16 h after a single bout of exercise (8,15,19,43,44). Available evidence from studies in humans and rodents suggests that acute exercise, like exercise training, increases insulin sensitivity without changes in proximal insulin signaling (reviewed in Ref.…”

Energy replacement attenuates the effects of prior moderate exercise on postprandial metabolism in overweight/obese men

“…40,41 The smaller effect of exercise on postprandial insulin concentrations when energy was replaced, compared to exercise with an energy deficit, is likely due to increased post-exercise repletion of muscle glycogen stores following the additional food that was provided in this trial, as restricting carbohydrate intake following exercise prolongs the duration of enhanced insulin sensitivity. 42 Our findings are consistent with long-term exercise training studies which indicate that exercise training without weight or fat loss (suggesting the absence of an exercise-induced energy deficit) improves insulin sensitivity, but that exercise with weight loss induces larger changes. 43 Thus, it seems clear that the insulinsensitizing effects of exercise are maximized when the energy expended is not replaced by increasing energy intake, however, the extent to which a residual benefit occurs when the energy expended is replaced is unclear.…”

Prior exercise increases phosphorylation of Akt substrate of 160 kDa (AS160) in rat skeletal muscle

“…The insulinindependent effect is evident during and shortly after exercise, but it reverses relatively rapidly, with most of the effect typically lost ϳ3-4 h postexercise in rat muscle (10,43). As the exercise effect on insulin-independent glucose transport subsides, glucose transport in the presence of a physiological insulin concentration can be substantially elevated (9,10,32,43).…”