Physical Therapy Assistant Practice Exam

What concept describes an increased response of the agonist following contraction of its antagonist?

1. Reciprocal inhibition

2. Irradiation

3. Successive induction

4. Rhythmic initiation

The correct answer is: Reciprocal inhibition

The concept that describes an increased response of the agonist following contraction of its antagonist is known as reciprocal inhibition. This physiological principle occurs when one muscle (the antagonist) contracts, resulting in a simultaneous relaxation of the opposing muscle (the agonist). This mechanism not only facilitates the smooth movement of muscles around a joint but also enhances the strength and effectiveness of the contraction of the agonist. In practical terms, during physical therapy, utilizing reciprocal inhibition can help increase flexibility and range of motion in a patient. For example, if a physical therapist guides a patient to contract their hamstrings (the antagonist), the quadriceps (the agonist) will receive a more significant neural input and can contract more forcefully when it is time for that muscle to engage. This principle is particularly important in rehabilitation settings, as it aids in improving muscle coordination and reducing the risk of injury. The other options, while related to muscle function and therapy, describe different concepts. Irradiation refers to the spread of muscle contraction to adjacent muscles, often used in techniques to enhance muscle strength. Successive induction relates to the increase in muscle strength or activation of consecutive muscle groups after preceding contractions, which is distinct from the specific interaction of agonists and antagonists. Rhythmic