Effect of physical training on the insulin resistance of aging.

Part of the insulin resistance associated with aging may be attributable to a loss of physical fitness. It was hypothesized that an increase in level of physical training would result in an increase in peripheral insulin action. Eleven healthy 60- to 80-yr-old subjects with normal oral glucose tolerance were studied by a euglycemic two-step hyperinsulinemic clamp before and after 12 wk of physical training. Weight and body composition were held constant, and the clamp was separated by 7 days from the last bout of exercise. There was a positive correlation before training between maximum O2 uptake (Vo2 max) and total body glucose disposal rate (M) at the 40 mU.m-2.min-1 insulin infusion (r = 0.69, P less than 0.02). After training Vo2 max increased 6.7%, M increased 13.4% during the 40 mU.m-2.min-1 and 11.0% during the 200 mU.m-2.min-1 insulin infusion. These results show that peripheral insulin resistance in older persons can be decreased by increasing the level of physical training, independent of changes in weight or body composition. Therefore a part of the insulin resistance of aging is reversible, and level of physical training should be considered in its measurement.