College of Massage Therapists of British Columbia (CMTBC) Practice Exam

What type of contraction occurs when the muscle generates less force than its maximum?

1. Isometric contraction

2. Eccentric contraction

3. Concentric contraction

4. Static contraction

The correct answer is: Concentric contraction

The correct answer refers to concentric contraction, which occurs when a muscle shortens while generating force, resulting in movement of a body part. In this scenario, when the muscle generates less force than its maximum capacity, it is still actively contracting but is unable to exert its full strength due to factors like the weight or resistance being less than what it can handle. This often occurs during activities like lifting a light object, where the muscle is able to contract but does so below its peak force capability. Isometric contraction, on the other hand, involves the muscle generating force without changing length, meaning there is no movement, and it’s not applicable when describing a force generation relative to maximum strength. Eccentric contraction refers to the muscle lengthening under tension while it is being forced to stretch, usually against a greater resistance, which again doesn't align with the description provided in the question. Static contraction isn’t typically used in this context; it primarily implies no movement, similar to isometric contractions. Overall, the terminology and mechanics related to concentric contractions provide the appropriate context for understanding how muscles can work at varying force levels.