Already in the beginning of the last century it was revealed that carbohydrate is an important fuel during exercise. Later in the late 1960s, pioneering muscle biopsy studies demonstrated that muscle glycogen contents is associated with exhaustion and that glycogen changes with exercise, recovery and training. This has later been followed by compelling research in glucose uptake regulation, and more mechanistic studies on the role of glycogen localization in cell functions and muscle performance. Thus, the importance of skeletal muscle glycogen as a fuel during exercise, and fundamental aspects of glycogen regulation is well documented. However, little is known about the precise mechanism that relates skeletal muscle glycogen to impaired muscle function and cell signaling. Further, fundamental questions remains unsolved, as how glycogen storage is regulated, fiber type differences in glycogen regulation and effects of training and disuse on the glycogen localization.

Recently, new techniques and ideas have evolved and shed novel light on the role of glycogen in cell function, especially in excitable tissue as skeletal muscle. In the symposium on “Role of glycogen in skeletal muscle regulation and function”, Saturday 27^th, we will exhibit and discuss recent data that addresses these long established questions. The presentations points to a diverse effects of different glycogen localizations on muscle function, and fiber type differences in key elements in the glycogen regulation.

Dr. Niels Ørtenblad

Chair as well as first speaker in this invited session is Dr. Niels Ørtenblad, Associate professor and head of research unit, Dept. of Sports Science and Clinical Biomechanics, University of Southern Denmark. He will during the talk provide experimental evidence in favor of a direct role of decreased glycogen, localized within the myofibrils, for the reduction in SR Ca²⁺ release during fatigue. This has been revealed at the level from isolated SR vesicles from human muscle after exercise and in single intact and mechanically skinned muscle fibres.

Dr. Robyn Murphy

The second speaker, Dr. Robin Murphy, Department of Zoology, La Trobe University, Melbourne, who is leading in single fibre western blotting and has a long research merit in glycogen associated protein localization and absolute content. In this talk, she will present and discuss compelling evidence for a distinct fibre type dependent regulation of glycogen related proteins in response to acute exercise in humans.

Dr. Clara Prats

The third speaker, Dr. Clara Prats, Copenhagen University, will on the base of studies on the complexity and the dynamics of intracellular compartments, discuss the intracellular compartmentalization as a regulator of glycogen metabolism. Here, she will review and summarize what it is known and what is still lacking to reach full understanding of the complexity of skeletal muscle glycogen metabolism and insulin signaling.

The symposia topic and the three talks will be of interest both for a broader physiological audience, as well as for the many researchers and members of the ECSS with specific interest in metabolism and muscle function.

The invited session [IS-PM05] Role of glycogen in skeletal muscle regulation and function will start 10:20 Saturday 27^th June in Lecture room: “High Live 1”

Post by Niels Ørtenblad