What type of muscle fibers are known for their quick contraction speed and high force production?

Type II fibers, also known as fast-twitch fibers, are characterized by their quick contraction speed and ability to produce high force. These fibers are well-suited for activities requiring short bursts of power, such as sprinting or weightlifting. They have a larger diameter compared to slow-twitch fibers, which allows them to generate more force but at the cost of endurance. Type II fibers rely primarily on anaerobic metabolism for energy, enabling them to perform effectively for short durations. This makes them integral in high-intensity, fast-paced activities where explosive strength and speed are necessary.

In contrast, Type I fibers are designed for endurance and are more efficient for prolonged activities, utilizing aerobic metabolism. Intermediate fibers can possess characteristics of both Type I and Type II, but they do not match the rapid force production capabilities of Type II fibers. Slow-twitch fibers are specifically geared towards endurance and sustained activities, making them less suitable when quick and powerful movements are required.