The review is aimed at presenting the state of current knowledge into the structure of a glycogen molecule as well as its synthesis and degradation during post mortem changes in muscle tissue. Currently-accepted model of the structure of glycogen molecule is that suggested by Whelan [Immonen, 2000; & Pösö Puolanne. 2005]. It has been demonstrated that the structure of a molecule is very well adjusted to the functioning of glycogen in muscles through strong packing of glucose particles and that glucose is well available for glycogenolytic enzymes due to strongly branched structure. The review provides results of research at pigs referring to the analysis of a variety of interactions of factors (mainly genetic ones, as HALⁿ/RYR^T and RN- genes) on the activity of enzymes related with synthesis and degradation of glycogen in muscles. Recent results of research into factors affecting the activity of glycogen debranching enzyme have shown that fast chilling of carcass is likely to limit the occurrence of PSE defect. Another aspect described in the review is the effect of residual glycogen on meat quality, whose occurrence has been reported in both pigs and cattle. It has been shown to lower the yield of meat in cooking, to affect a decrease in protein content of muscle tissue and to influence the sensory quality of meat.