International Sports Sciences Association (ISSA) Trainer Practice Exam

Disable ads (and more) with a membership for a one time $2.99 payment

Prepare for your ISSA Trainer Exam with comprehensive study tools, including multiple-choice questions and detailed explanations. Gain confidence and achieve your certification in fitness training!

Practice this question and more.


What is true about Type II muscle fibers?

  1. They are entirely aerobic

  2. They are entirely anaerobic

  3. They contain a mixture of aerobic and anaerobic properties

  4. They are primarily slow-twitch fibers

The correct answer is: They are entirely anaerobic

Type II muscle fibers, also known as fast-twitch fibers, are primarily characterized by their anaerobic properties, which means they rely mainly on anaerobic metabolic processes for energy. This allows them to generate quick bursts of power and strength, making them essential for high-intensity, short-duration activities like sprinting or heavy lifting. They possess fewer mitochondria and less myoglobin compared to Type I fibers, which contributes to their reliance on anaerobic metabolism. Additionally, Type II fibers are well-suited for activities that involve rapid contractions and higher force production, although this comes at the cost of endurance. Therefore, the defining feature of Type II muscle fibers is their predominance in anaerobic energy systems, affirming the accuracy of the statement regarding their energetic preferences.