National Certification Board for Therapeutic Massage & Bodywork (NCBTMB) Practice Exam

What is a true statement regarding isometric contraction?

1. Muscle lengthening occurs during this contraction

2. No muscle lengthening occurs during this contraction

3. It requires movement of the joint

4. It primarily works fast-twitch muscle fibers

The correct answer is: No muscle lengthening occurs during this contraction

Isometric contraction is characterized by the muscle maintaining a constant length while generating tension. This means that during an isometric contraction, the muscle does not shorten or lengthen, even though it is actively engaged. This type of contraction is commonly used in various strength training and rehabilitation exercises. Muscles can produce force without any visible movement of the joint involved, as the muscle fibers engage and create tension without changing their length. During isometric activities, such as holding a weight in a fixed position or pushing against an immovable object, the muscle stays in a steady state, leading to stabilization and strength development without joint movement. Therefore, the assertion that no muscle lengthening occurs during this contraction accurately encapsulates the definition and functioning of isometric contractions.