Which muscle fibers use both anaerobic and aerobic energy systems and have moderate force production?

Type 2 A muscle fibers, often referred to as fast-twitch oxidative fibers, are characterized by their ability to utilize both anaerobic and aerobic energy systems. This dual capability allows them to sustain longer-duration activities than Type 2 B fibers, which predominantly rely on anaerobic metabolism and fatigue quickly. Type 2 A fibers can produce a moderate amount of force and are well-suited for activities that involve bursts of speed or power, but still demand endurance.

Their moderate force production stems from a balanced approach; they are not as powerful as Type 2 B fibers but do not fatigue as quickly due to their oxidative capacity. This makes them highly adaptable and useful for a variety of athletic performances that require both strength and endurance, such as middle-distance running or circuit training. In contrast, Type 1 fibers are primarily aerobic and focus on endurance, while Type 2 B fibers are geared towards high-intensity, short-duration activities. Skeletal muscle refers to the muscle tissue itself and does not specify the fiber types, making it too broad for this question.