Reciprocal vs. Autogenic Inhibition Explained. Muscle Spindle and Golgi Tendon Organ Physiology

anatomy muscle physiology Sep 13, 2022

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By: Danielle Abel, MSN, FNMS, CSCS(c)

Structurally and functionally, muscle spindles and golgi tendon organs (GTO) have uniquely different roles within the body. 

Structural Differences

Structurally, muscle spindles are located within the muscle itself. Muscle spindles are considered intrafusal fibers because they gather and send proprioceptive (sensory) information to the spinal cord.

Golgi tendon organs structurally are located outside the muscle, in the tendon, where it is attached to the muscle.

The differences between these structures become easier to understand when you relate them to their function within the body. Each structure has its unique purpose, and we can't have one without the other. Essentially they are complementary structures. 

Functional Differences

Muscle spindles sense both stretch within the muscle and facilitate agonist muscle activation (simplified below). Muscle spindles also inhibit activation of the antagonist muscle (also simplified below). Whereas golgi tendon organs only cause agonist inhibition. 

  • Muscle Spindle Function within a Back Squat
    • Facilitate activation of the agonist (the quad muscles - turns them "on") 
    • Inhibit activation of the antagonist (the hamstrings muscles - turns them "off")
  • Golgi Tendon Organ Function within a Back Squat
    • Inhibits activation of the agonist (the quad muscles - turns them "off")

All of these sensory processes are types of communication that occur between the muscles and the spinal cord.

Reciprocal vs. Autogenic Inhibition

As a result of this detailed communication from a structural and functional perspective, our body moves (or should move) in the way it was designed to. Otherwise, when you tried to back squat, your hamstrings would shorten and not lengthen, which would not allow flexion to occur at the level of the hips and knees. 

If you break down the word, reciprocal simply means actions that are complimentary to one another or one action occurring due to the other action. 

  • Muscle spindles have 2 functions, so they perform reciprocal inhibition 

Likewise, if you break down the word autogenic, it simply means self or refers to self. 

  • Golgi tendon organs act upon themselves and have singular functions, so they perform autogenic inhibition 

See how they each play a unique role within movement?

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