Doud J R, Walsh J M
Division of Pulmonary and Critical Care Medicine, Loyola University Chicago Stritch School of Medicine, Illinois.
Respir Physiol. 1993 Dec;94(3):241-50. doi: 10.1016/0034-5687(93)90021-2.
Electromyogram (EMG) power spectral analysis has been widely used to detect muscle fatigue. Non-fatigue factors that influence the EMG power spectrum must be well understood to ensure accurate interpretation. We explored the effect of muscle temperature on the EMG power spectrum in an isolated canine diaphragm preparation with intact neuro-vascular supply. In 5 animals, diaphragm temperature was continuously recorded with an intramuscular thermocouple, and the EMG signal was recorded with intramuscular wire electrodes. Data were obtained from spontaneous isometric diaphragm contractions while the diaphragm underwent passive cooling from 40 to 30 degrees C. The EMG power spectrum was determined using fast Fourier transform and each spectrum was characterized by its center frequency (fc). A direct linear relationship was found between diaphragm temperature and the EMG fc. The mean slope of the temperature-EMG fc relationship was 2.9% fc.degree C-1. In conclusion, diaphragm temperature is a major determinant of the diaphragmatic EMG power spectrum, and should be controlled when this index is employed in the investigation of muscle fatigue.
肌电图（EMG）功率谱分析已被广泛用于检测肌肉疲劳。为确保准确解读，必须充分了解影响EMG功率谱的非疲劳因素。我们在具有完整神经血管供应的离体犬膈肌标本中探究了肌肉温度对EMG功率谱的影响。在5只动物中，用肌内热电偶连续记录膈肌温度，并用肌内线电极记录EMG信号。数据来自膈肌自发等长收缩，在此期间膈肌从40℃被动冷却至30℃。使用快速傅里叶变换确定EMG功率谱，每个谱以其中心频率（fc）为特征。发现膈肌温度与EMG fc之间存在直接线性关系。温度-EMG fc关系的平均斜率为2.9% fc·℃⁻¹。总之，膈肌温度是膈肌EMG功率谱的主要决定因素，在将该指标用于肌肉疲劳研究时应加以控制。
