ACE Personal Trainer Practice Exam

What is a characteristic of a muscle spindle compared to Golgi tendon organs?

1. Less active but more numerous

2. More responsive to tension

3. More reactive to stretch rather than tension

4. Located mainly in tendons

The correct answer is: More reactive to stretch rather than tension

Muscle spindles are specialized sensory receptors located within the belly of skeletal muscles and play a crucial role in detecting changes in muscle length and the rate of that change, or stretch. This responsiveness to stretch is their primary characteristic. Muscle spindles are designed to provide information about the muscle's length and how quickly it is changing, making them critical for reflex actions such as maintaining posture and coordinating movement. Compared to Golgi tendon organs, which are located at the junction between muscles and tendons, muscle spindles specifically are more reactive to stretching of the muscle fibers. Golgi tendon organs, on the other hand, are more responsive to tension within the tendons, providing feedback about the force exerted by muscles during contraction. This fundamental difference highlights how muscle spindles are specialized for monitoring stretch, making option C the correct choice. Other characteristics of muscle spindles include their distribution within muscles, where they outnumber Golgi tendon organs, as well as their mechanism of functioning that primarily focuses on stretch rather than the force or tension exerted by the muscles, thereby emphasizing their role in muscle stretch sensitivity.