ACSM Certified Personal Trainer (CPT) — Question 6

What is the fundamental unit of muscle contraction?

Answer options

• A. Myofibril
• B. Sarcomere
• C. Myosin
• D. Sarcolemma

Correct answer: B

Explanation

The sarcomere is the smallest functional unit of muscle contraction, consisting of repeating units that enable muscle fibers to contract. Myofibrils are composed of multiple sarcomeres, while myosin is a protein involved in the contraction process, and the sarcolemma is the muscle cell membrane. Therefore, while all options are related to muscle structure and function, only the sarcomere specifically identifies the fundamental unit of contraction.