Weir J P, McDonough A L, Hill V J
Program in Physical Therapy, University of Osteopathic Medicine and Health Sciences, Des Moines, IA 50312, USA.
Eur J Appl Physiol Occup Physiol. 1996;73(3-4):387-92. doi: 10.1007/BF02425504.
The purpose of this study was to examine the effect of manipulation of joint angle on electromyographic (EMG) fatigue curves at different sites over the quadriceps muscle group. Eight subjects performed isometric knee extensions at 0.26, 0.79, and 1.31 rad from full extension for 1 min at 50% of maximum. EMG signals were recorded with a branched electrode lead system at proximal and distal sites over the vastus lateralis and vastus medialis. The 1-min contractions were analyzed for changes in integrated EMG (IEMG) and median power frequency (MPF) over time. The results showed that the fatigue slopes for IEMG were greatest at 0.79 rad. However, the MPF data showed the greatest slopes at 0.26 rad. We hypothesize that the decline in MPF at 0.26 rad is due to activation failure while the increase in IEMG at 0.79 rad is driven by contractile failure. In addition, the EMG fatigue rates within each joint angle were similar at all sites.
本研究的目的是探究关节角度的改变对股四头肌群不同部位肌电图（EMG）疲劳曲线的影响。八名受试者在膝关节完全伸展位置的0.26、0.79和1.31弧度处进行等长伸膝运动，以最大力量的50%持续1分钟。使用分支电极导联系统在股外侧肌和股内侧肌的近端和远端部位记录EMG信号。分析这1分钟收缩过程中积分肌电图（IEMG）和中位功率频率（MPF）随时间的变化。结果显示，IEMG的疲劳斜率在0.79弧度时最大。然而，MPF数据显示在0.26弧度时斜率最大。我们推测，0.26弧度时MPF的下降是由于激活失败，而0.79弧度时IEMG的增加是由收缩失败驱动的。此外，每个关节角度下各部位的EMG疲劳率相似。
