Which combination explains the increased flexibility after hold-relax with agonist contraction PNF stretching of the hamstrings?

Which combination explains the increased flexibility after hold-relax with agonist contraction PNF stretching of the hamstrings?

• A. Autogenic Inhibition and Reciprocal Inhibition
• B. Stretch Inhibition and Crossed-Extensor Inhibition
• C. Autogenic Inhibition, Stretch Inhibition, and Reciprocal Inhibition
• D. Reciprocal Inhibition and Crossed-Extensor Inhibition

Answer: (A)

Hold-relax with agonist contraction increases flexibility through neural changes that temporarily lessen resistance from the stretched muscle and its antagonist. When the hamstrings perform the isometric contraction against resistance, the Golgi tendon organs detect the increased tension and trigger autogenic inhibition. This reduces the excitability of the hamstrings’ motor neurons, allowing them to be moved into a greater stretch without fighting the barrier of the stretch reflex. At the same time, this contraction of the hamstrings promotes reciprocal inhibition of the muscles opposing knee flexion, mainly the quadriceps. By relaxing the antagonist, the leg can be moved into a deeper passive stretch more comfortably and effectively. Other reflex mechanisms like cross-inhibition across limbs or a general “stretch inhibition” concept aren’t the primary drivers in this technique, so the combination of autogenic inhibition and reciprocal inhibition best explains the observed increase in flexibility.

Hold-relax with agonist contraction increases flexibility through neural changes that temporarily lessen resistance from the stretched muscle and its antagonist. When the hamstrings perform the isometric contraction against resistance, the Golgi tendon organs detect the increased tension and trigger autogenic inhibition. This reduces the excitability of the hamstrings’ motor neurons, allowing them to be moved into a greater stretch without fighting the barrier of the stretch reflex.

At the same time, this contraction of the hamstrings promotes reciprocal inhibition of the muscles opposing knee flexion, mainly the quadriceps. By relaxing the antagonist, the leg can be moved into a deeper passive stretch more comfortably and effectively.

Other reflex mechanisms like cross-inhibition across limbs or a general “stretch inhibition” concept aren’t the primary drivers in this technique, so the combination of autogenic inhibition and reciprocal inhibition best explains the observed increase in flexibility.