Kellis E, Baltzopoulos V
Division of Sport and Recreation, University of Northumbria at Newcastle, Newcastle upon Tyne, UK.
Eur J Appl Physiol Occup Physiol. 1997;76(3):253-9. doi: 10.1007/s004210050244.
The purpose of this study was to examine the effects of moment of antagonistic muscle on the resultant joint moment during isokinetic eccentric and concentric efforts of the knee extensors. Ten males performed maximum eccentric and concentric knee extension and flexion efforts on a Biodex dynamometer at 0.52 rad.s-1 (30 degrees.s-1). Electromyographic (EMG) activity of vastus medialis and biceps femoris (hamstrings) was also recorded. The antagonistic moment of the hamstrings was determined by recording the integrated EMG (iEMG)/ moment relationship at different levels of muscle effort. The iEMG/moment curves were fitted using second-degree polynomials. The polynomials were then used to predict the antagonistic moment exerted by the hamstrings from the antagonist iEMG. The antagonistic moment had a maximum of 42.92 Nm and 28.97 Nm under concentric and eccentric conditions respectively; paired t-tests indicated that this was a significant difference (P < 0.05). These results indicate that the resultant joint moment of knee extensors is the result of both agonist and antagonist muscle activation. The greater antagonist muscle activity under concentric activation conditions may be partly responsible for the lower resultant joint concentric moment of knee extensors compared with the corresponding eccentric activation. The antagonist moment significantly affects comparisons between the isokinetic moments and agonist EMG and in vitro force measurements under different testing (muscle action and angular velocity) conditions.
本研究的目的是在膝关节伸肌等速离心和向心运动过程中，考察拮抗肌力矩对合成关节力矩的影响。10名男性在Biodex测力计上以0.52弧度·秒⁻¹（30度·秒⁻¹）进行最大离心和向心膝关节伸展与屈曲运动。同时记录股内侧肌和股二头肌（腘绳肌）的肌电图（EMG）活动。通过记录不同肌肉用力水平下的积分肌电图（iEMG）/力矩关系来确定腘绳肌的拮抗力矩。iEMG/力矩曲线采用二次多项式进行拟合。然后利用这些多项式根据拮抗肌iEMG预测腘绳肌施加的拮抗力矩。在向心和离心条件下，拮抗力矩分别最大为42.92牛米和28.97牛米；配对t检验表明这是一个显著差异（P < 0.05）。这些结果表明，膝关节伸肌的合成关节力矩是主动肌和拮抗肌激活共同作用的结果。与相应的离心激活相比，向心激活条件下更大的拮抗肌活动可能是膝关节伸肌合成关节向心力矩较低的部分原因。拮抗力矩显著影响不同测试（肌肉动作和角速度）条件下等速力矩、主动肌EMG和体外力量测量之间的比较。
