Type I muscle fibers are predominantly aerobic. True or False?

Type I muscle fibers, also known as slow-twitch fibers, are indeed predominantly aerobic. These fibers are designed to be fatigue-resistant and support endurance activities, making them ideal for long-duration, low-intensity exercise such as marathon running or cycling. Due to their high myoglobin content, extensive capillary networks, and abundance of mitochondria, Type I fibers utilize oxygen effectively to produce energy through aerobic metabolism.

This characteristic allows them to sustain activity over prolonged periods without quickly succumbing to fatigue. In contrast, Type II muscle fibers are more suited for explosive, high-intensity activities, relying more on anaerobic pathways for quick bursts of energy. Thus, the assertion that Type I muscle fibers are predominantly aerobic is accurate and corroborated by their physiological properties.