Department of Human Services, University of Virginia, Charlottesville, VA, United States.
J Electromyogr Kinesiol. 2010 Oct;20(5):840-4. doi: 10.1016/j.jelekin.2009.11.004. Epub 2009 Dec 29.
A relationship exists between muscles of the lumbar spine and those of the lower extremity where the quadriceps become more inhibited after lumbar paraspinal. The purpose of this experiment was to compare surface electromyography (sEMG) total frequency content after lumbar paraspinal fatiguing exercise.
50 subjects performed fatiguing lumbar extension exercise indexed by downward shifts in median frequency calculated from lumbar paraspinal sEMG signal. Before and after each exercise set we recorded maximal, isometric knee extension torque and quadriceps central activation ratio (QI) using the superimposed burst technique while recording vastus lateralis sEMG. We calculated total frequency content of the sEMG signal (fEMG(TOTAL)) as the area of the quadriceps sEMG frequency spectrum. Quadriceps fEMG(TOTAL) decreased from baseline following the first and second exercise sets. There was no significant change in quadriceps sEMG median frequency among baseline and post-exercise measures. The change in fEMG(TOTAL) was correlated with the change in QI following the first (r=-0.41, P=0.003) and second (r=-0.32, P=0.02) exercise sets.
Quadriceps fEMG(TOTAL) decreased following fatiguing lumbar extension exercise, in the absence of a significant change in quadriceps median frequency.
腰椎脊柱和下肢肌肉之间存在关联，股四头肌在腰部脊柱旁疲劳后会受到更大的抑制。本实验的目的是比较腰部脊柱旁疲劳运动后表面肌电图（sEMG）总频率含量。
50 名受试者进行了以中频下降为指标的腰部伸展疲劳运动，中频下降是通过腰椎脊柱旁 sEMG 信号计算得出的。在每组运动前后，我们使用叠加突发技术记录了最大、等长膝关节伸展扭矩和股四头肌中央激活比（QI），同时记录了股外侧肌 sEMG。我们计算了 sEMG 信号的总频率含量（fEMG（TOTAL）），即股四头肌 sEMG 频谱的面积。股四头肌 fEMG（TOTAL）在第一组和第二组运动后从基线下降。基线和运动后测量的股四头肌 sEMG 中频无显著变化。fEMG（TOTAL）的变化与第一组（r=-0.41，P=0.003）和第二组（r=-0.32，P=0.02）运动后 QI 的变化相关。
在股四头肌中频无显著变化的情况下，疲劳性腰部伸展运动后股四头肌 fEMG（TOTAL）减少。
