MEDICAL PHYSIOLOGY

Detailed explanation-1: -Type IIB fibers have high myosin ATPase activity (pH 9.4), are fast twitch, have low oxidative and high glycolytic capacity, and fatigue rapidly.

Detailed explanation-2: -In humans, type I, or slow-twitch, fibers possess slower twitch speeds and are relatively fatigue resistant. Type IIa fibers, or fast oxidative glycolytic (FOG) fibers, present higher twitch speeds than type I fibers but are less fatigue resistant.

Detailed explanation-3: -Fast glycolytic fibers fatigue quickly, permitting them to only be used for short periods. However, during these short periods, the fibers are able to produce rapid, forceful contractions associated with quick, powerful movements.

Detailed explanation-4: -Fast twitch fibers (e). have low resistance to fatigue and quick twitches. There are a couple different types of fast twitch fibers (Type IIa and Type IIb), but the main difference is that they twitch quickly, fatigue quickly, and use anaerobic metabolism.

Detailed explanation-5: -If a fiber primarily produces ATP through aerobic pathways it is oxidative. More ATP can be produced during each metabolic cycle, making the fiber more resistant to fatigue. Glycolytic fibers primarily create ATP through anaerobic glycolysis, which produces less ATP per cycle.