Inhibition of the soleus H-reflex in standing man.
There exists evidence to support the notion that the segmental reflex system is not fixed and inflexible, but rather is highly modifiable under a variety of circumstances. In this study the H-wave and M-wave recruitment curves were obtained from 19 subjects, utilizing the procedures outlined by Hugon. Each subject was tested on one day under two randomly administered conditions: (1) standing; and (2) prone. Once in place, the recording and stimulating electrodes were not removed until the completion of the study, to ensure that exact placement was maintained. A percutaneous electrical stimulus (1 ms pulse) was utilized to elicit the pulse. The current was monitored with a current probe, and was increased in 2 mA increments from zero until a maximal M-wave was obtained. An analysis of variance revealed significant increases in the amplitude of the H-wave (P < 0.05) when the subject was prone with no significant increases in the M-wave. The results indicate significantly higher H/M ratios with the subjects in the prone position. Therefore, it is concluded that H-reflex amplitude is tonically depressed when the subject is maintaining a standing position.
Koceja
D M
DM
Department of Kinesiology, Indiana University, Bloomington 47405.
Trimble
M H
MH
Earles
D R
DR
D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D009132:Muscles / Q000294:innervation*; D011187:Posture; D016684:Prone Position; D012016:Reference Values