The effect of acupuncture on alpha-motoneuron excitability.

The effect of short duration and sustained manual acupuncture on alpha-motoneuron excitability was studied using the Soleus H-reflex. The acupuncture points GB-34 and SP-9 were needled and stimulated manually. Normalised H-reflex and M-wave recruitment curves were constructed and the ratio of the slope of the ascending part of the H-reflex recruitment curve (Hslp) to the slope of the ascending part of the M-wave recruitment curve (Mslp) was used for assessing changes in alpha-motoneuron excitability. Sustained manual acupuncture caused significant reduction of alpha-motoneuron excitability, while short duration manual acupuncture had no effect. The reduction of alpha-motoneuron excitability following sustained manual acupuncture occurred fifteen minutes after cessation of acupuncture and was still present at 30 minutes. The relationship between perceived intensity of acupuncture sensation (Deqi) and changes in alpha-motoneuron excitability was also studied, but no significant correlation was found. This study indicates that manual acupuncture would be useful in clinical conditions associated with increased alpha-motoneuron excitability and that when using acupuncture for these conditions, higher intensity of perceived acupuncture sensation (Deqi) may not result in greater degree of reduction in alpha-motoneuron excitability.