What are the three types of muscle fibers?

1. Type I: Slow-twitch oxidative fibers

- Fatigue-resistant

- Contain many mitochondria

- Generate ATP aerobically

- High capillarization

- Red in color

2. Type IIa: Fast-twitch oxidative-glycolytic fibers

- Moderately fatigue-resistant

- Can generate ATP both aerobically and anaerobically

- Red in color

3. Type IIx: Fast-twitch glycolytic fibers

- Fatigable

- Generate ATP anaerobically

- White in color