What is a characteristic of slow twitch fibers?

Slow twitch muscle fibers, also known as type I fibers, are characterized by their red color due to the high presence of myoglobin, which is an oxygen-binding protein. This red color indicates a rich supply of blood vessels and a high capacity for aerobic metabolism, allowing these fibers to sustain prolonged periods of activity without fatigue. Their design makes them more efficient for endurance activities, such as long-distance running or cycling, where oxygen consumption is critical.

In comparison, fast twitch fibers (type II) typically appear white, fatigue more quickly, and are more efficient at generating quick bursts of power. This distinction highlights the specific functional adaptations of slow twitch fibers, which are vital for activities requiring endurance and sustained performance.