What is the effect of Golgi tendon organ activation on the agonist and antagonist muscles?

• A. Agonist inhibitory; antagonist facilitatory
• B. Agonist facilitatory; antagonist inhibitory
• C. Both inhibitory
• D. Both facilitatory

Answer: (A)

Golgi tendon organs sense tendon tension and trigger a protective reflex that limits the muscle generating the force. When these receptors are activated, Ib afferents connect in the spinal cord with inhibitory interneurons that decrease the activity of the motor neurons to the agonist muscle. That autogenic inhibition reduces the contracting muscle’s force. At the same time, the signal shifts the balance toward the antagonist, either by releasing its motor neurons from inhibition or by facilitating them, so the antagonist can oppose the action. The net result is inhibition of the agonist and facilitation of the antagonist. This mechanism helps prevent tendon damage from over-tension.