Which mechanism describes Golgi tendon organs sensing increased tension when a muscle contracts or stretches, leading to inhibition of the contracting muscle and activation of the antagonist?

• A. Reciprocal inhibition
• B. Autogenic inhibition
• C. Active stretching
• D. Post-isometric relaxation

Answer: (B)

Golgi tendon organs sense tendon tension and trigger autogenic inhibition. When a muscle contracts or is stretched enough to raise tendon tension, Ib fibers from the Golgi tendon organ send signals to the spinal cord. Those signals activate inhibitory interneurons that reduce the activity of the alpha motor neurons to the same (contracting) muscle, causing it to relax. This protection also helps shift drive toward the antagonist muscle.

Reciprocal inhibition, by contrast, involves the antagonist being inhibited during agonist contraction via stretch reflex pathways, not the tendon-tension reflex from Golgi organs. Active stretching is simply the act of stretching, not a reflex mechanism. Post-isometric relaxation is a technique that leverages autogenic inhibition after an isometric hold, but the described mechanism specifically refers to autogenic inhibition caused by Golgi tendon organ signaling.