Increased Insulin Sensitivity and Insulin Binding to Monocytes after Physical Training

Abstract

We studied the effect of physical training on in vivo tissue sensitivity to insulin and insulin binding to monocytes in six previously untrained healthy adults. Physical training (one hour of cycle-ergometer exercise four times per week for six weeks) failed to alter body weight but resulted in a 20 per cent increase (P<0.02) in maximal aerobic power (V̇O₂ max) and a 30 per cent increase (P<0.01) in insulin-mediated glucose uptake (determined by the insulin clamp technique). The increase in insulin sensitivity correlated directly with the rise in V̇O₂ max (P<0.05). Binding of [¹²⁵I]insulin to monocytes also rose by 35 per cent after physical training (P<0.02), primarily because of an increase in the concentration of insulin receptors.

Our data indicate that physical training increases tissue sensitivity to insulin in proportion to the improvement in physical fitness. Physical training may have a role in the management of insulin-resistant states, such as obesity and maturity-onset diabetes, that is independent of its effects on body weight. (N Engl J Med 301:1200–1204, 1979)