Which property is NOT associated with Type 1 muscle fibers?

Type 1 muscle fibers, also known as slow-twitch fibers, are characterized by their ability to engage in sustained, endurance activities. One of the distinguishing properties of these fibers is their reliance on aerobic metabolism for energy production, which allows them to sustain activity for extended periods without fatiguing quickly. This is in contrast to anaerobic processes, which are associated with quicker bursts of energy and fatigue.

The properties linked to Type 1 muscle fibers include low fatigability, high myoglobin content, and small fiber size. Low fatigability means these fibers can maintain activity over longer durations. The high myoglobin content allows for better oxygen storage and transport within the muscle, enhancing aerobic metabolism. The small fiber size contributes to their ability to perform prolonged activities since smaller fibers often have a higher density of mitochondria and blood vessels, supporting aerobic functions.

In summary, the characteristic that is not associated with Type 1 muscle fibers is their predominantly anaerobic nature, as they primarily use aerobic metabolism for energy.