What type of muscle fibers contract quickly and possess high anaerobic capacity?

• A. Slow-Twitch Fiber
• B. Fast-Twitch Fiber
• C. Intermediate Fiber
• D. Dynamic Fiber

Answer: (B)

Fast-twitch fibers, also known as Type II muscle fibers, are characterized by their ability to contract quickly and generate force rapidly. This type of muscle fiber is primarily used in high-intensity, explosive movements such as sprinting or weightlifting. Due to their reliance on anaerobic metabolism, fast-twitch fibers can produce energy without the need for oxygen, allowing them to sustain high-intensity activity for a short duration.

These fibers have a higher concentration of glycogen and fewer mitochondria compared to slow-twitch fibers, making them more suited for activities that require quick bursts of energy rather than endurance. Consequently, athletes engaged in sports that demand speed, power, and quick recovery often develop a greater proportion of fast-twitch muscle fibers, enhancing their performance in such activities.