Median frequency of surface EMG signal of antagonist muscles during repeated contractions

The surface EMG signals of the antagonist muscles of normal human elbow joint were pecked-up during repeated contractions both in extension and flexion modes. The normalized median frequency (MMF) of the antagonist EMG signal was higher than that of agonist in each repeating contraction. The slopes of two regression lines of agonist/antagonist MMF increased, and there intercepts decreased as repeat ed contraction times increased.