Physical Therapy Assistant Practice Exam

Which description identifies reciprocal inhibition in the context of muscle response?

1. Increased muscle fiber length

2. Inhibition of antagonist during agonist contraction

3. Facilitated muscle shortening

4. Strengthening of the flexors only

The correct answer is: Inhibition of antagonist during agonist contraction

Reciprocal inhibition refers to the neurological phenomenon where the activation of one muscle (the agonist) leads to the simultaneous inhibition of its antagonist muscle. This is a crucial mechanism that allows for smooth and coordinated movements, enabling one muscle group to contract while the opposing muscle group is relaxed to prevent conflicting actions during movement. In this context, when a muscle contracts (for example, the biceps during a bicep curl), the antagonist muscle (the triceps) is inhibited to allow the contraction to occur effectively. This concept is foundational in physical therapy and rehabilitation practices, highlighting the importance of the neuromuscular system in controlling movement and ensuring efficient motion without resistance or conflict between opposing muscle groups. The other options do not accurately define reciprocal inhibition. Lengthening of muscle fibers relates more to stretching and flexibility, while facilitated muscle shortening describes the process of muscles contracting but doesn’t capture the aspect of inhibition. Lastly, the strengthening of flexors only fails to recognize the balance required between agonist and antagonist muscles in any functional movement.