Type IIA Muscle Fibers: Glycogen, Glycolysis & Exercise Performance

Type IIA muscle fibers

Type IIA muscle fibers, also known as fast-twitch oxidative fibers, are intermediate between type I and type IIB fibers in terms of their contractile properties and metabolic characteristics. They have a large quantity of glycogen and mainly use glycolysis to synthesize ATP. Type IIA fibers are recruited during activities that require moderate to high levels of force and power, such as sprinting and jumping.