van Boxtel A, Goudswaard P, van der Molen G M, van den Bosch W E
J Appl Physiol Respir Environ Exerc Physiol. 1983 Jan;54(1):51-8. doi: 10.1152/jappl.1983.54.1.51.
Endurance and changes in electromyogram (EMG) power spectra were investigated during a fatiguing static contraction at 50% of the maximum EMG amplitude in two jaw-elevator muscles (masseter and temporalis) and five facial muscles (frontalis, corrugator supercilii, zygomaticus major, orbicularis oris, and buccinator). Relatively high endurance was found in orbicularis oris, frontalis, and corrugator supercilii muscles; intermediate endurance was found in zygomaticus major, buccinator, and temporalis muscles; and low endurance was found in the masseter muscle. The last muscle showed a relatively fast linear decrease of the median frequency of the power spectrum. The other muscles showed a much slower, exponential decrease. The median frequency appeared to reflect reliably the changes in the shape of the power spectra during fatigue. Large differences between the shape of power spectra of different muscles in the unfatigued state were found. These, however, were unrelated to endurance and degree of spectral shift during fatigue.
在两块咬肌（咬肌和颞肌）以及五块面部肌肉（额肌、皱眉肌、颧大肌、口轮匝肌和颊肌）以最大肌电图（EMG）幅度的50%进行疲劳性静态收缩期间，研究了耐力和肌电图功率谱的变化。发现口轮匝肌、额肌和皱眉肌的耐力相对较高；颧大肌、颊肌和颞肌的耐力中等；咬肌的耐力较低。最后一块肌肉的功率谱中位数频率呈相对快速的线性下降。其他肌肉则呈现出慢得多的指数下降。中位数频率似乎可靠地反映了疲劳期间功率谱形状的变化。在未疲劳状态下，发现不同肌肉的功率谱形状存在很大差异。然而，这些差异与疲劳期间的耐力和频谱偏移程度无关。
