GLOSSARY

Liver Glycogen Storage Table

Glycogen capacity and depletion depend on muscle mass, diet and exercise; there is no fixed storage number for every athlete.

Glycogen is a highly branched storage form of glucose, especially important in muscle and liver. It differs from blood glucose and body fat and changes with activity and feeding.

Liver glycogen helps support blood glucose between meals and during activity, whereas muscle glycogen mainly fuels the muscle in which it is stored. The stores serve different roles. Their amounts depend on previous eating, muscle mass, training status and recent exercise, rather than one fixed capacity applying to every athlete.

Hard or prolonged exercise can use substantial glycogen, and reduced stores may limit the ability to sustain intensity. An ordinary blood-glucose reading does not establish adequate muscle stores. Sleep, fatigue, muscle damage and energy intake also affect performance, so one sign cannot identify glycogen as the sole cause of a decline.