Fast-Twitch Muscle Fiber

**Semantic type:** Cell

**Definition:** A large-diameter skeletal muscle fiber that uses glycogen reserves rather than oxygen-rich blood for quick energy and a more rapid production of force. Fast twitch muscle fibers have a low oxidative capacity and can produce ATP without the need for oxygen, resulting in a higher activation threshold and a higher velocity signal conduction.

**Synonyms:** - Muscle Fibers, Fast-Twitch - Type II Muscle Fiber - Type II Skeletal Muscle Fiber