Effect of exercise on glucose and insulin utilization in the forearm

Glucose and insulin utilization by forearm muscle was examined at rest and during exercise. Care was taken to have a steady state with regard to arterial plasma concentrations for 1 hr prior to as well as during the measurements. At rest, insulin uptake was linearly related to arterial insulin concentration. During exercise with no change in arterial plasma concentration of either glucose or insulin, there was an increase in uptake of both substances, and the relation of insulin uptake to concentration became exponential. It is hypothesizes that the latter phenomenon is due to an increase in cellular uptake of insulin by a mechanism independent of membrane receptors.