Related Experiment Videos
Glucose utilization during exercise: influence of endurance training
J F Wojtaszewski1, E A Richter
1Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, Denmark.
Acta Physiologica Scandinavica
|May 13, 1998
Summary
Exercise increases skeletal muscle glucose uptake, but endurance training reduces this utilization during submaximal exercise. This occurs due to decreased GLUT4 protein translocation to the muscle cell surface.
Area of Science:
- Exercise Physiology
- Skeletal Muscle Metabolism
- Glucose Transport
Background:
- Skeletal muscle glucose utilization significantly increases during exercise compared to rest.
- This heightened utilization is driven by increased glucose supply, enhanced membrane transport, and elevated muscle metabolism.
- The relationship between blood glucose concentration and muscle uptake is nearly linear around physiological levels (approx. 5 mM).
Purpose of the Study:
- To investigate the signaling pathways governing glucose transport in contracting skeletal muscle.
- To understand the effects of endurance training on muscle glucose utilization during exercise.
Main Methods:
- Analysis of glucose utilization kinetics in human skeletal muscle during exercise.
- Examination of insulin signaling pathways (insulin receptor substrate 1, phosphatidylinositol 3-kinase) in response to muscle contractions.
- Assessment of GLUT4 protein content and sarcolemmal translocation following endurance training.
Main Results:
- Muscle glucose uptake during exercise is not linearly dependent on insulin signaling.
- Contractions do not activate the proximal insulin signaling cascade for glucose transport.
- Endurance training reduces glucose utilization during submaximal exercise despite increased total GLUT4.
- This reduction is linked to blunted exercise-induced GLUT4 translocation to the sarcolemma.
Conclusions:
- Skeletal muscle glucose transport during exercise involves complex signaling, potentially involving calcium, independent of proximal insulin pathways.
- Endurance training alters the regulation of glucose uptake, leading to decreased utilization during submaximal exercise through reduced GLUT4 translocation.