Is the Motor Point Better in Reproducibility of Surface EMG Signal﹖

　　　　　根據過往報告位於股直肌前方末端三分之一上的運動點之穴位－伏兔，其肌電圖訊號比從股骨大粗隆至脛骨股骨交接點間之中心點，其穩定性、再生性更為良好。其結果與過往認為從肌腹上取得之表肌電圖訊號優於運動點之理論架構有明顯之差異，故本研究對於6位測試者使用Cybex 340等速肌力測定儀，對其右側股四頭肌在等速及等長肌力收縮下測定其表面肌電圖訊號，以研究穴位其位置上之表面肌電圖訊號的穩定性、再生性是否優於運動點。研究之方法是以Myosystem 1000記錄分別放置在股直肌中心點及股直肌運動點也就是穴位－伏兔上之電極所取得的表面統合肌電圖訊號，兩者加以相互比較。 結果顯示，在肌肉中心點上所取得之表面統合肌電圖訊號，其幅度較大，而且在同一天或隔天再次重複測量時，其結果始終是非常穩定。故本結果對於在運動點上取得之表面肌電圖訊號優於肌腹之理論不能支持。
　　　　　The EMG signals acquired from acupoint Fu Tu (a motor point in rectus femoris) were reported to be more stable and reproducible than those from the middle point between grater trochanter to tibio-femoral junction of knee in standing position. It was different from the concept of better surface EMG signal from muscle belly than motor point. For studying whether the motor point is better surface electrode location for stability and reproducibility of EMG signal, 6 normal subjects were examined at right quadriceps in isometric and isokinetic contractions by Cybex 340 dynamometer. The active electrodes of surface electromyography (S-EMG) were placed at midpoint of the rectus femoris and the motor point of rectus femoris for comparison. The integrated EMG (IEMG) signals were recorded and stored by Myosystem 1000. The result in this study showed that surface integrated EMG (S-IEMG) signals from the midpoint of the muscle was bigger in amplitude, more stable in repetitive measurements in within day as well as in between days. The results do not support the motor point is better in surface EMG signal than muscle belly.