Muscle glycogen

Muscle glycogen is an essential store of carbohydrate fuel for both high-
intensity exercise and also prolonged activity. Glycogen is a polysaccharide
made up of a large number of monosaccharide glucose units joined together by
two types of bonds i.e. 1,4-α bonds and 1,6-α bonds. The former produce
straight chains of glucose molecules but after every ten glucose units or so, the
chain is branched by the 1,6 bond. Fig. 4 illustrates the branching nature of
glycogen. (For more detail see Instant Notes in Biochemistry, Chapters J1 and J2.)
Normal muscle glycogen stores have a concentration of 350 mM kg–1 dry
muscle, although this can be increased significantly by a high carbohydrate diet
and reduced significantly by repeated bouts of sprinting or a single prolonged
bout of exercise or when on a low carbohydrate diet for around 2–4 days.

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