Effect of training on insulin-mediated glucose uptake in human muscle
Dela, F.; Mikines, K.J.; von Linstow, M.; Secher, N.H.; Galbo, H.
American Journal of Physiology 263(6): E1134-E1143
1992
ISSN/ISBN: 0002-9513 PMID: 1476187 Document Number: 395522
During insulin stimulation whole body glucose uptake is increased in trained compared with untrained humans. However, it is not known which tissue is reponsible. Seven young male subjects bicycle trained one leg for 10 wk at 70% of maximal O-2 consumption ( ovrhdot V-O-2max). Sixteen hours after last exercise bout, a three-step euglycemic hyperinsulinemic clamp (clamp 1) was performed (insulin levels, means +- SE: 9 +- 1, 53 +- 3, 174 +- 5, and 2,323 +- 80 was mu-U/ml), with measurement of arteriovenous differences and blood flow in both legs. After 6 days of detraining subjects were restudied, having exercised the untrained leg 16 h before. ovrhdot V-O-2max for trained (T) and untrained (UT) legs was 52 +- 2 vs. 44 +- 2 ml cntdot ml-1 cntdot kg-1 (P lt 0.05). In clamp 1 glucose uptake in T and UT legs was 1.0 +- 0.2 vs. 0.5 +- 0.1 mg cntdot min-1 (basal), 9.7 +- 2.3 vs. 6.7 +- 1.7 (P lt 0.05) (step I), 19.2 +- 2.8 vs. 14.3 +- 2.0 (P lt 0.05) (step II), and 22.8 +- 2.3 vs. 18.6 +- 2.2 (P lt 0.05) (step III). During insulin infusion lactate release (P lt 0.05) (8.9 +- 1.8 vs. 2.9 +- 0.9 mu-mol cntdot min-1 cntdot kg-1 (step I), 24.6 +- 3.1 vs. 12.5 +- 2.6 (step III)) and glycogen storage (P lt 0.1) calculated by indirect calorimetry (6.7 +- 2.3 vs. 5.0 +- 1.7 mg cntdot min-1 cntdot kg-1 (step I), 16.8 +- 2.1 vs. 14.1 +- 1.8 (step III)) were always higher in T than in UT legs. Release of glycerol, free fatty acids, and tyrosine and clearance of insulin were not influenced by training. Insulin-mediated glucose uptake was not increased after detraining or a single bout of exercise. In conclusion, training increases sensitivity and responsiveness of insulin-mediated glucose uptake in human muscle by local mechanisms. Glycolysis and glycogen storage are equally enhanced. The training effect represents a genuine adaptation to repeated exercise but is short lived. Insulin clearance in muscle is not influenced by training.