Katsavelis Dimitrios, Threlkeld A Joseph
Department of Physical Therapy, Creighton University, Omaha, NE 68178, United States.
Department of Physical Therapy, Creighton University, Omaha, NE 68178, United States.
J Electromyogr Kinesiol. 2014 Aug;24(4):502-7. doi: 10.1016/j.jelekin.2014.04.004. Epub 2014 Apr 16.
Muscle co-activation around the knee is important during ambulation and balance. The wide range of methodological approaches for the quantification of co-activation index (CI) makes comparisons across studies and populations difficult. The present study determined within- and between-session reliability of different methodological approaches for the quantification of the CI of the knee extensor and flexor muscles during maximum voluntary isometric contractions (MVICs). Eight healthy volunteers participated in two repeated testing sessions. A series of knee extension MVICs of the dominant leg with concomitant torque and electromyographic (EMG) recordings were captured. CI was calculated utilizing different analytical approaches. Intraclass correlation coefficient (ICC) showed that within-session measures displayed higher reliability (ICC>0.861) and lower variability (Coefficient of variation; CV<21.8%) than between-session measures (ICC<0.645; CV>24.2%). A selection of a 500ms or larger window of RMS EMG activity around the PT delivered more reliable and less variable results than other approaches. Our findings suggest that the CI can provide a reliable measure for comparisons among conditions and is best utilized for within-session experimental designs.
在行走和平衡过程中，膝关节周围的肌肉协同激活很重要。用于量化协同激活指数（CI）的方法种类繁多，这使得跨研究和人群进行比较变得困难。本研究确定了在最大自主等长收缩（MVICs）期间，用于量化膝关节伸肌和屈肌CI的不同方法在组内和组间的可靠性。八名健康志愿者参加了两次重复测试。记录了优势腿一系列膝关节伸展MVICs的伴随扭矩和肌电图（EMG）。利用不同的分析方法计算CI。组内相关系数（ICC）表明，与组间测量相比，组内测量显示出更高的可靠性（ICC>0.861）和更低的变异性（变异系数；CV<21.8%）（ICC<0.645；CV>24.2%）。与其他方法相比，选择围绕PT的500ms或更大的RMS EMG活动窗口可提供更可靠且变异性更小的结果。我们的研究结果表明，CI可为不同条件之间的比较提供可靠的测量指标，并且最适合用于组内实验设计。
