Glycogen Resynthesis

Glycogen resynthesis is the rebuilding of glycogen stores after they have been depleted or reduced. Glycogen is a branched polymer of glucose stored mainly in skeletal muscle and the liver. In exercise physiology, glycogen resynthesis usually refers to the restoration of skeletal muscle glycogen during recovery after exercise has reduced muscle glycogen stores .^1,2

After exercise, glucose is taken up by muscle cells and used to synthesize glycogen. The enzyme glycogen synthase catalyzes a key step in extending glycogen chains. Exercise-induced glycogen depletion increases glycogen synthase activity and enhances glucose uptake by previously exercised muscle, favoring glycogen restoration .^1,2

When muscle glycogen has been substantially depleted, post-exercise glycogen resynthesis can include two overlapping phases. An initial rapid phase can occur with relatively little dependence on insulin. A subsequent, slower phase becomes more dependent on insulin, which promotes glucose uptake and glycogen synthesis. Carbohydrate availability is also important because it supplies the glucose needed to rebuild glycogen .^1,2

Glycogen resynthesis is closely related to glycogenesis but is a more specific term. Glycogenesis describes the biochemical synthesis of glycogen generally, whereas glycogen resynthesis emphasizes restoration of glycogen that was previously used. When glycogen stores rise above their usual pre-exercise level during recovery, this is called glycogen supercompensation .^1,2