| Summary: | 碩士 === 國立體育學院 === 教練研究所 === 92 === In sports, we often need to overcome muscle fatigue to maintain the performance interact by agonist and antagonist muscle. It is important to solve the poor control of agonist-antagonist activity muscle after fatigue. The purposes of this study are to evaluate the effect of agonist muscle fatigue on the error of force control and investigate the change of ago-ant muscle relationship. Ten healthy subjects were recruited. The subject was instructed to perform fast and slow isometric ankle dorsiflexion to a target force level of 40% MVC. The MVC force, error of force generation, and EMG of tibialis anterior and soleus were recorded before and after voluntary isometric fatigue. The results revealed that following fatigue, the MVC of dorsiflexion decreased significantly (p<.0001). The error of force generation increased in both fast and slow contractions after fatigue, wherein, the amount of increasing is larger in fast contractions. The co-contraction time of EMG increased (p<.05) in slow movement but not in fast one. EMG activities of TA and SOL muscles increased after muscle fatigue at both speeds (p<.05). No triphasic EMG was found in our data. In conclusion, there was enough time in slow contractions to modify ago-ant control strategies which minimized the error of target setting. The increase of random error after fatigue could not be adjusted by ago-ant muscle control. In order to enhance performance in sports, coaches are suggested to re-educate ago-ant muscle control of fast movement after fatigue.
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