Exercise Causes Muscle GLUT4 Translocation in an Insulin-Independent Manner

Glucose uptake in skeletal muscle is dependent on the translocation of GLUT4 glucose transporters to the plasma membrane. The most important stimulators of glucose transport in skeletal muscle are insulin and exercise. Glucose uptake in skeletal muscle during exercise induces acceleration of many processes compared to the resting state. The scientific literature does not underline the role played by muscle contraction to increase glucose uptake with insulin-independent mechanisms. Search on Pub Med (May 05, 2015) using the key words "contraction and glucose uptake and muscle" gives 717 reports, while a search using the key words "insulin and glucose uptake and muscle" cites 5676 publications. The present paper describes the role of exercise in the muscle glucose uptake. Contraction of muscle induces GLUT4 translocation in the absence of insulin. There are different intracellular "pools" of GLUT4, one stimulated by insulin and another one stimulated by exercise. The roles exerted by AMPK, AICAR, calcium, NO, glycogen and hypoxia in the glucose uptake during exercise are emphasized. The effects of these phenomena on human wellness are reported.