Previous exercise training influences functional sprouting of rat hindlimb motoneurons in response to partial denervation.

Rats had soleus and plantaris muscles of one hindlimb partially denervated by cutting L4 radicular nerve, and functional sprouting of intact L5 motoneurons was estimated physiologically 10 days later. Animals that had undergone daily exercise training (10 weeks) prior to partial denervation showed evidence of enhanced sprouting in plantaris, and reduced sprouting in soleus. Exercise training, known to cause motoneuron changes, enhances short-term sprouting of fast muscle motoneurons. Differences between plantaris and soleus responses probably reflect differing sprouting stimuli, or degree of prior overload.