Heterogeneity of motor units activating single Golgi tendon organs in cat leg muscles.

The aim of this study was to investigate whether an individual Golgi tendon organ can signal the contraction of motor units with different physiological properties. The axonal conduction velocity and tetanic tension of motor units were examined in four muscles of the cat leg (peroneus brevis, peroneus longus, tibialis anterior and soleus). The motor units which were found to activate a given tendon organ had contractile properties dispersed over the same range as those of the whole muscle population. The proportion of tendon organ-activating motor units found in the studied samples suggests that altogether, the Golgi tendon organs of a muscle monitor the contraction of every motor unit in this muscle.