Autogenic Effects of Static Muscle Stretch in Spastic Man

Autogenic inhibition of the H reflex was produced by static stretch of the triceps surae in nine patients with spasticity due to spinal cord lesions. This inhibitory effect was abolished by diffuse infiltration of the triceps surae with procaine hydrochloride, but enhanced by ischemia sufficient to block the ankle jerk without altering the direct motor response. In contrast to the triceps surae, the H reflex of the pretibial flexors was facilitated by stretch of these muscles. It is concluded that these effects are consistent with activation of secondary spindle endings which are known to produce autogenic inhibition of extensor reflexes and autogenic facilitation of flexor reflexes in spinal preparations.