Golgi Tendon Organs: Neuroscience Update with Relevance to Stretching and Proprioception in Dancers

Abstract

This article reviews the neuroscience of the Golgi tendon organ, a type of muscle sensory receptor. The intent is also to update and correct erroneous notions regarding its functional significance, particularly related to its involvement in reflexes, proprioception, and stretching techniques used in dance training. Historical research about the function of the Golgi tendon organ (GTO) has led to four erroneous views: 1. The GTO serves a protective function by responding only to muscle tension at the extreme end-range of motion; 2. Sensations from GTOs do not reach the cerebral cortex and therefore serve no role in conscious proprioception and kines-thesia; 3. The GTO and its reflex circuit (autogenic inhibition) prevent its muscle from contracting by “turning it off”; and 4. During contract-relax stretching, the GTO autogenic inhibition reflex circuit is responsible for the muscle relaxation phase and the accompanying increased range of motion. Recent research has shown that these early views are inaccurate. There is new evidence regarding the role of the GTO. 1. A GTO responds to even weak active contractions throughout the range of motion, although GTOs are much less sensitive to passive tension than to active tension. 2. GTO sensations probably do reach the cerebral cortex, buried in the fissure between the motor and sensory cortex “strips.” This information allows dancers to know where their limbs are in space. GTOs also provide unconscious proprioception, via the cerebellum, which helps dancers to learn new motor skills and improve execution of movements. 3. The GTO and its reflex (autogenic inhibition) reduce, but do not shut off, the excitability of the motor neuron and its innervated muscle. The ultimate reflex effect depends on the sum of multiple other inputs on the motor neuron. GTO input may reduce muscle activity, but does not “turn it off.” 4. During contract-relax stretching, the GTO autogenic reflex creates inhibition that lasts only as long as the muscle's active contraction. Therefore, GTO activity is unlikely to significantly affect the subsequent relaxation phase of the stretch. Other receptors and spinal circuits likely serve this function. It is hoped that this updated information will correct several erroneous notions about GTOs that have persisted in the dance kinesiology literature. Thus, dance kinesiology teachers, researchers, and health practitioners can provide accurate information to their students, readers, and patients.