Effects of different types of physical training on insulin action in human peripheral tissues-use of the euglycemic clamp technique-

Physical training has been shown to improve glucose tolerance and insulin action in peripheral tissues. In the present study, regular (R) and high (H)-dose euglycemic clamp procedures were performed to determine the effects of different types of physical training on insulin action (sensitivity/responsiveness) in 10 longdistance runners (LR), 10 weight-lifters (WL) and 12 healthy controls (HC), The amount of infused glucose (glucose metabolism, GM) during euglycemic clamping is a measure of the peripheral tissue sensitivity and/or responsiveness to insulin. For R clamping, when GM was calculated per unit body weight (BW), GM in LR(11.92±1.22 mg/kg BW.min)and WL (9.28±0.63 mg/kg BW.min) was significantly (P<0.05) higher than that in HC (7.44±0.39 mg/kg BW.min). When calculated per unit lean body mass(LBM), LR (15.07±1.56 mg/kg LBM.min) differed from HC (9.15±0.59 mg/kg LBM. min, P<0.05), whereas the value in WL (11.50±0.93mg/kg LBM.min) was identical to that in HC. For H clamping, there was no significant change in these three groups when GM was calculated per unit BW or LBM. These results suggest that enhancement of insulin action by physical training is due to an increase in insulin sensitivity, rather than to an increase in insulin responsiveness, and that aerobic exercise, for example longdistance running, is more effective for the improvement of decreased sensitivity to insulin, which is observed in patients with simple obesity and diabetes, than anaerobic exercise such as weight-lifting. (Jpn. J. Phys, Fitness Sports Med. 1991, 40 : 315∼320).