Borrani F, Candau R, Millet G Y, Perrey S, Fuchslocher J, Rouillon J D
Laboratoire Sport Performance et Santé, 34090 Montpellier, Faculté des Sciences du Sport, Université de Montpellier I, France.
J Appl Physiol (1985). 2001 Jun;90(6):2212-20. doi: 10.1152/jappl.2001.90.6.2212.
The goal of this study was to use spectral analysis of EMG data to test the hypothesis that the O2 uptake VO2) slow component is due to a recruitment of fast fibers. Thirteen runners carried out a treadmill test with a constant speed, corresponding to 95% of the velocity associated with maximal VO2. The VO2 response was fit with the classical model including three exponential functions. Electrical activity of six lower limb muscles (vastus lateralis, soleus, and gastrocnemius of both sides) was measured using electromyogram surface electrodes. Mean power frequency (MPF) was used to study the kinetics of the electromyogram discharge frequency. Three main results were observed: 1) a common pattern of the MPF kinetics in the six muscles studied was noted; 2) MPF decreased in the first part of the exercise, followed by an increase for all the muscles studied, but only the vastus lateralis, and gastrocnemius muscles of both sides increased significantly (P < 0.05); and 3) the beginning of the MPF increase of the four muscles mentioned above corresponded with the beginning of the slow component. Our results suggest a progression in the average frequency of the motor unit discharge toward the high frequencies, which coheres with the hypothesis of the progressive recruitment of fast-twitch fibers during the VO2 slow component. However, this interpretation must be taken with caution because MPF is the result of a balance between several phenomena.
本研究的目的是利用肌电图（EMG）数据的频谱分析来检验以下假设：摄氧量（VO2）慢成分是由于快肌纤维的募集所致。13名跑步者在跑步机上以恒定速度进行测试，该速度相当于最大VO2时速度的95%。VO2反应采用包含三个指数函数的经典模型进行拟合。使用肌电图表面电极测量双侧六个下肢肌肉（股外侧肌、比目鱼肌和腓肠肌）的电活动。平均功率频率（MPF）用于研究肌电图放电频率的动力学。观察到三个主要结果：1）在所研究的六块肌肉中，MPF动力学呈现出一种共同模式；2）在运动的第一阶段，MPF下降，随后所有研究的肌肉均出现上升，但只有双侧的股外侧肌和腓肠肌显著增加（P<0.05）；3）上述四块肌肉MPF增加的开始与慢成分的开始相对应。我们的结果表明，运动单位放电的平均频率向高频发展，这与VO2慢成分期间快肌纤维逐渐募集的假设一致。然而，由于MPF是多种现象平衡的结果，所以对这一解释必须谨慎对待。
