Observations on the variability of the H reflex in human soleus

✍ Scribed by Kozo Funase; Timothy S. Miles

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 162 KB
• Volume: 22
• Category: Article
• ISSN: 0148-639X
• DOI: 10.1002/(sici)1097-4598(199903)22:3<341::aid-mus6>3.0.co;2-r

✦ Synopsis

H reflexes were evoked in human soleus by stimulating the tibial nerve at a constant intensity. Each trial was then assigned to one of three groups on the basis of the amplitude of its H reflex; all trials in each group were then full-wave rectified and reaveraged. There was a strong positive relationship between the amplitude of the H reflex and the level of electromyographic activity in the muscle at the time of onset of the H reflex, which reflects the activity of the motoneuronal pool when the afferent volley arrived. Thus, much of the variability of the H reflex is due to small changes in the level of activation of the motoneuronal pool during repeated trials. The steady torque preceding the H reflex was a poor predictor of the H-reflex amplitude, presumably because of the delay between the changes in the electrical activity of motoneurons and the mechanical outcome thereof.