NETA Personal Trainer Practice Exam

Which type of muscle fiber is characterized as slow-twitch oxidative?

1. Type 1

2. Type 2

3. Type 3

4. Type 4

The correct answer is: Type 1

Type 1 muscle fibers are characterized as slow-twitch oxidative fibers. These fibers are known for their endurance capabilities and are highly effective in utilizing oxygen to generate energy. They are particularly suited for prolonged, low-intensity activities such as long-distance running or cycling. The predominant features of Type 1 fibers include a higher density of mitochondria, rich amounts of myoglobin, and a large supply of blood vessels, all of which contribute to their ability to sustain aerobic metabolism. This allows them to produce energy more efficiently over extended periods while minimizing fatigue. In contrast, Type 2 fibers, which encompass fast-twitch fibers, are primarily designed for quick bursts of power and strength but rely more on anaerobic metabolism, which leads to quicker fatigue. The other types mentioned are generally not classified in terms of conventional muscle fiber typology, making Type 1 the clearly defined category for slow-twitch oxidative characteristics.