All Glossary Terms
Anatomy
Type I Muscle Fiber (Slow-Twitch)
Muscle fibers optimized for endurance with high fatigue resistance.
Type I (slow-twitch) muscle fibers are optimized for sustained activity. They have high mitochondrial density, use oxygen efficiently, and resist fatigue. They generate less force but can work for extended periods. Endurance athletes tend to have higher proportions of Type I fibers. These fibers are recruited for low-intensity, prolonged activities.
Examples
- Used for walking, posture
- Dominant in marathon runners
- High oxidative capacity