Kroon G W, Naeije M, Hansson T L
Arch Oral Biol. 1986;31(9):603-8. doi: 10.1016/0003-9969(86)90084-1.
During 7 sessions at weekly intervals, 10 healthy males performed the same endurance test three times by isometrically contracting the masseter muscles at 20, 30, 40, 50, 60, 75 or 90 per cent of maximal electromyographic activity. The interval between the tests in any one session was 30 s. Changes in the surface electromyogram were monitored by calculating the changes in mean power frequency (MPF) of the signals. With the higher contraction levels, endurance times were shorter, the MPF shifted to lower frequencies more rapidly and the MPF value was lower at the end of the test. At these levels, the subjects reported lack of power as the sole reason for stopping the test but at low levels, pain was the important reason. The endurance time and the rate of MPF shift for the second and third test of each experiment were the same. For the first test, the endurance time was longer (p less than 0.025) and the rate of MPF shift was lower (p less than 0.05). Thus the analysis of specific electromyographic (MPF) indicators provides information about the development of muscle fatigue.
在每周一次、共七次的 sessions 期间，10名健康男性通过在最大肌电图活动的20%、30%、40%、50%、60%、75%或90%水平上等长收缩咬肌，对相同的耐力测试进行了三次。任何一次测试之间的间隔为30秒。通过计算信号的平均功率频率（MPF）变化来监测表面肌电图的变化。收缩水平越高，耐力时间越短，MPF向较低频率的转变越快，并且在测试结束时MPF值越低。在这些水平上，受试者报告缺乏力量是停止测试的唯一原因，但在低水平时，疼痛是重要原因。每个实验的第二次和第三次测试的耐力时间和MPF转变率相同。对于第一次测试，耐力时间更长（p小于0.025），MPF转变率更低（p小于0.05）。因此，对特定肌电图（MPF）指标的分析提供了有关肌肉疲劳发展的信息。
