M wave and H-reflex of soleus muscle before and after electrical muscle stimulation in healthy subjects.
OBJECTIVE
This study was the preliminary research for applying the evaluation of muscle fatigue using the evoked electromyography in the field of physical therapy. In this study, we speculated that muscle fatigue was induced by electrical muscle stimulation (EMS). And we studied the M wave and amplitude ratio of H/M before and after EMS because the M wave and amplitude ratio of H/M have been often used as the parameter in the study of muscle fatigue.


METHODS
Subjects were five healthy males. In this study, the intermittent EMS (30 Hz) was administered to the soleus muscle of dominant leg for 10 minutes and we analyzed the amplitude of maximal M wave and the amplitude ratio of H/M in this study.


RESULTS
The amplitude of maximal M wave after EMS significantly decreased compared with that before the EMS (p < 0.05). And the results of amplitude ratio of H/M varied as follows; decrease in two subjects, increase in one subject and unchanged results in two subjects.


CONCLUSIONS
M wave reflects the excitability of muscle membrane related to the change in force during muscle fatigue and the amplitude ratio of H/M has been considered as the index of a relative excitability of alpha motoneuron pool. From the results of this study, we considered that muscle fatigue was induced by EMS as predictability because the amplitude of maximal M wave significantly decreased after EMS. And it was considered that the excitability of spinal neural function corresponding to fatigued soleus muscle by EMS was not consist change in this study. Therefore we thought that results of amplitude ratio of H/M might be influenced by excitability of spinal neural function in subject's ordinary state.


CONCLUSIONS
It was suggested that the muscle fatigue was induced because the amplitude of maximal M wave significantly decreased after EMS in this study. And also it was suggested the excitability of spinal neural function corresponding with fatigued soleus muscle by EMS was not consist change in this study.
Tanino
Y
Y
Department of Physical Therapy, Kansai Vocational College of Medicine. tanino@kansai.ac.jp
Daikuya
S
S
Nishimori
T
T
Takasaki
K
K
Suzuki
T
T
D000328:Adult; D004599:Electric Stimulation Therapy; D004576:Electromyography; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D026741:Physical Therapy Modalities