Viitasalo J H, Komi P V
Eur J Appl Physiol Occup Physiol. 1977 Sep 16;37(2):111-21. doi: 10.1007/BF00421697.
Electromyographic (EMG) activity of m. rectus femoris muscle was registered from young male and female subjects during maintained isometric knee extension at 60% of maximal voluntary contraction. The following EMG parameters were analyzed for the entire fatigue time: integrated EMG (IEMG), averaged motor unit potential (AMUP) and power spectral density function (PSDF). The results indicated a slight but continuous rise of IEMG during the fatigue period. AMUP showed sensitivity to fatigue with increase in amplitude, rise time, and number of spikes counted. PSDF was also easily affected by fatigue so that the total power density curve was shifted towards lower frequencies with a high frequency decay. The mean power frequency decreased linearily as a function of fatigue time. The findings suggest that in addition to natural recruitment of new motor units the fatigue is characterized by marked reduction in the conduction velocities of action potential along the used muscle fibers.
在年轻男性和女性受试者以最大自主收缩的60%进行持续等长伸膝时，记录股直肌的肌电图（EMG）活动。分析了整个疲劳期的以下EMG参数：积分肌电图（IEMG）、平均运动单位电位（AMUP）和功率谱密度函数（PSDF）。结果表明，在疲劳期IEMG略有但持续上升。AMUP对疲劳敏感，其幅度、上升时间和计数的棘波数量增加。PSDF也很容易受到疲劳影响，以至于总功率密度曲线向低频偏移且高频衰减。平均功率频率随疲劳时间呈线性下降。研究结果表明，除了自然募集新的运动单位外，疲劳的特征还在于沿使用的肌纤维动作电位传导速度的显著降低。
