Exercise and insulin sensitivity: a review.

mam Physical activity has a beneficial effect on insulin sensitiv-ity in normal as well as insulin resistant populations. A distinc-tion should be made between the acute effects of exercise andgenuine training effects. Up to two hours after exercise, glu-cose uptake Is in part elevated due to Insulin independentmechanisms, probably Involving a contraction-induced increaseIn the amount of CLUT4 associated with the plasma membraneand T-tubules. However, a single bout of exercise can increaseinsulin sensitivity for at least 16 h post exercise in healthy aswell as NIDDM subjects. Recent studies have accordingly shownthat acute exercise also enhances insulin stimulated GLUT4translocation. Increases in muscle CLUT4 protein content con-tribute to this effect, and in adddition It has been hypothesizedthat the depletion of muscle glycogen stores with exerciseplays a role herein. Physical training potentiates the effect ofexercise on insulin sensitivity through multiple adaptations inglucose transport and metabolism. In addition, training mayelicit favourable changes in lipld metabolism and can bringabout improvements in the regulation of hepatic glucose out-put, which is especially relevant to NIDDM. It Is concluded thatphysical training can be considered to play an important, if notessential role in the treatment and prevention of insulin Insen-sitivity.• Key words: Skeletal muscle, GLUT4, diabetes, insulin resist-ance, physical training.