What are type two muscle fibers?
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Type two muscle fibers, also known as fast-twitch fibers, are designed for quick, high-force activities. They are used in explosive actions like sprinting or jumping. Unlike slow-twitch fibers, which are activated in almost all daily activities and are more endurance-oriented, fast-twitch fibers are specifically engaged during high-force activities and are less frequently used in regular movement [1].
Fast-twitch fibers are known to be larger and contract at a higher velocity compared to slow-twitch fibers. They are also more glycolytic, meaning they primarily use glucose for fuel, which can lead to quicker fatigue. The proportion of fast vs. slow-twitch fibers varies from muscle to muscle and person to person [2].
Maintaining these fibers is crucial, especially as one ages. As individuals age, there is a tendency for a reduction in fast-twitch fibers, which impacts tasks requiring quick responses, like catching oneself from a fall [1](). Engaging in exercises that stress these fibers can help maintain their function and delay the effects of aging [3]().
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