Shoaib Bin Aleem, Muhammad Mazhar Hussain, Yasir Farooq.
Role of skeletal muscle glycogen in exercise.
Pak Armed Forces Med J Jan ;59(2):169-70.

Glucose, the primary fuel for all body cells, is derived primarily from carbohydrates. If needed, glucose can also be metabolized from protein. After a meal, some of the glucose, which is not used immediately for fuel, travels to the liver and skeletal muscles, where it is converted to glycogen through the process of glycogenesis [1]. Glycogen is the major reservoir of carbohydrate in the body. It comprises of long chain polymers of glucose molecules containing 120,000 glucose units in each molecule. The body stores approximately 450-550 grams of glycogen within the muscles and liver that is used during exercise. Skeletal muscles are the largest reservoir of glycogen as three fourth of the total glycogen in body is stored in skeletal muscles. Although liver cells store glycogen up to 8-10% of their weight while muscle cells can store glycogen up to 1-3% of the muscle mass but muscle is much greater in quantity due to its greater mass [2]. When body’s glucose level drops, the liver releases glucose into the blood stream by converting some of its glycogen back into glucose through glycogenolysis. Muscle cells, on the other hand, are unable to reconvert glycogen into glucose. Instead, they convert glycogen directly to fuel through a process called glycolysis [3]. This present article summarizes our understanding regarding the role of glycogen in enhancing the capability of skeletal muscles during exercise.

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