What type of muscle fibers are known for fast contraction and low resistance to fatigue?

The type of muscle fibers characterized by fast contraction and low resistance to fatigue are the Type 2 B fibers, also known as fast-twitch glycolytic fibers. These fibers are specifically designed for rapid and powerful movements, which is essential in activities requiring short bursts of strength and speed, such as sprinting or heavy weightlifting.

Type 2 B fibers rely primarily on anaerobic metabolism for energy, which allows them to generate quick and forceful contractions. However, this energy system is less efficient over longer periods, leading to quicker fatigue compared to other fiber types. This is why Type 2 B fibers are not suitable for endurance activities, as they fatigue more rapidly when sustained effort is required.

In contrast, Type 1 fibers (slow oxidative) are more resistant to fatigue and are optimized for endurance activities, relying predominantly on aerobic metabolism. Type 2 A fibers (fast-twitch oxidative fibers) possess characteristics of both fast and slow fibers and are more resistance to fatigue than Type 2 B fibers but not as powerful. Understanding the distinctions among these fiber types helps in designing training programs that align with the specific athletic goals and performance needs of individuals.