| Fast-Twitch Muscle Fiber; Fast-Twitch Muscle Fibers; Fiber, Fast-Twitch Muscle; Fiber, Red Muscle; Fiber, White Muscle; Fibers, Fast-Twitch Muscle; Fibers, Red Muscle; Fibers, White Muscle; Muscle Fiber, Fast-Twitch; Muscle Fiber, Red |
| Skeletal muscle fibers having high myofibrillar ATPase activity, high glycolytic enzyme activities, and an intermediate glycogen content which produce a fast twitch. There are two types. Fast fatigable fibers, also called white fibers, have a low myoglobin content, and a small mitochondrial content, and fatigue rapidly due to their limited glycogen content and low capacity for oxidative metabolism. Fast fatigue-resistant fibers, also called red fibers, have a large mitochondrial content and a high myoglobin content, related to their resistance to fatigue. (From Best, Physiological Basis of Medical Practice, 12th ed, p100) |
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