Characteristics of changes of electromyogram in the process of tibial anterior muscle figure caused by voluntary motion and induced by electric stimulation
In order to gain an insight into the pattern of changes of excitability of the neuro-muscular system, the authors based their object on 10 healthy males and applied two types of motion forms, namely, muscular contraction with maximum voluntary degree (group V) and muscular contraction induced by electric stimulation (group I), to observes the superficial electromyogram (sEMG) and induced electromyogram (iEMG) of tibial anterior muscle and soleus muscle when tibial anterior muscle fatigued as a result of ankle joint dorsal flexion, and revealed the follow- ing findings: 1) a decreasing trend occurred to the integral quantity and mean frequency of sEMG of testees in groups V and I, and such changes of testees in group I were more obvious; 2) with respect to testees in group I, the Mmax and ratio H/Mmax of tibial anterior muscle (agonist) were significantly lowered, and there was no significant change to the Mmax and ratio H/Mmax of soleus muscle (antagonist) after tibial anterior muscle fatigued; 3) with re- spect to testees in group V, ratio H/Mmax of tibial anterior muscle and soleus muscle was significantly lowered after the occurrence of muscle fatigue, but there was no significant change to the Mmax of both muscles. Conclusions: When the muscle fatigued, not only the spinal motor neurons of the agonist were restrained, but also the spinal mo- tor neurons of the antagonist were affected similarly, but the said changes were not completely the same due to the difference between muscular contraction modes.