Stensdotter Ann-Katrin, Dalén Tore, Holmgren Christer, Häger-Ross Charlotte
Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
J Orthop Res. 2008 Feb;26(2):217-24. doi: 10.1002/jor.20491.
The popliteus muscle is short and deeply situated in the posterior aspect of the knee, and contributes to control knee joint position. Little is known how activation of the popliteus is controlled. We hypothesized that for the purpose of securing knee joint position, the popliteus would be activated prior to the prime movers of the knee, and that activation would occur earlier and be amplified with increased structural laxity due to joint loading direction and position. Surface and fine wire electromyography (EMG) was used to measure onset and amplitude of muscle activity in the popliteus and three parts of the quadriceps in 10 healthy women (age 25 +/- 4 years). Subjects performed seated isometric knee extensions in 30 degrees and 90 degrees knee flexion in open (OKC) and closed kinetic chain (CKC) in a reaction time task. The popliteus was activated after the quadriceps in all tasks, but with shorter latency relative to the quadriceps in CKC, independent of knee flexion angle. EMG amplitude was greatest for all muscles in OKC in the 30 degrees knee flexion. Biomechanical variables alone do not explain popliteus activation. In addition to biomechanics, behavioral, and habitual aspects need to be considered in further studies.
腘肌短小且深位于膝关节后方，有助于控制膝关节位置。目前对于腘肌激活的控制方式知之甚少。我们推测，为确保膝关节位置，腘肌会在膝关节主要运动肌之前被激活，并且由于关节负荷方向和位置导致结构松弛增加时，激活会更早发生且增强。使用表面肌电图和细丝肌电图（EMG）来测量10名健康女性（年龄25±4岁）腘肌和股四头肌三个部分的肌肉活动起始时间和幅度。受试者在反应时间任务中，于膝关节30度和90度屈曲时，在开链（OKC）和闭链（CKC）状态下进行坐位等长伸膝动作。在所有任务中，腘肌均在股四头肌之后被激活，但相对于CKC中的股四头肌，其潜伏期较短，且与膝关节屈曲角度无关。在膝关节30度屈曲时，OKC中所有肌肉的EMG幅度最大。仅生物力学变量无法解释腘肌的激活情况。除生物力学外，行为和习惯方面在进一步研究中也需要考虑。
