Certified Personal Trainer (NSCA) Practice Exam

What is a distinct characteristic of Type 1 muscle fibers compared to Type II muscle fibers?

1. Higher endurance

2. Higher force output

3. Faster contraction speed

4. Lower recovery time

The correct answer is: Higher endurance

Type 1 muscle fibers, also known as slow-twitch fibers, are characterized by their higher endurance capacity compared to Type II fibers, which are referred to as fast-twitch fibers. Type 1 fibers are specifically designed for prolonged activities. They have a rich supply of capillaries, a high concentration of mitochondria, and significant myoglobin content, which allows for efficient aerobic metabolism and sustained energy production. This makes them particularly effective for activities such as long-distance running or cycling, where endurance is critical. In contrast, Type II muscle fibers are built for quick bursts of power and strength, exhibiting higher force output and faster contraction speeds but lower endurance. These fibers rely more on anaerobic processes, making them less suited for endurance activities. Recognizing this distinction helps athletes and trainers tailor their training programs according to individual muscle fiber compositions and performance goals.