Biomedical Engineering Institute, Boğaziçi University, 34342 Bebek, Istanbul, Turkey.
J Biomech. 2010 Oct 19;43(14):2665-71. doi: 10.1016/j.jbiomech.2010.06.002. Epub 2010 Jul 23.
The goals of the present study were (1) to measure the previously unstudied isometric forces of activated human Gracilis (G) muscle as a function of knee joint angle and (2) to test whether length history effects are important also for human muscle. Experiments were conducted intraoperatively during anterior cruciate ligament (ACL) reconstruction surgery (n=8). Mean peak G muscle force, mean peak G tendon stress and mean optimal knee angle equals 178.5±270.3N, 24.4±20.6 MPa and 67.5±41.7 °, respectively. The substantial inter-subject variability found (e.g., peak G force ranges between 17.2 and 490.5 N) indicate that the contribution of the G muscle to knee flexion moment may vary considerably among subjects. Moreover, typical subject anthropometrics did not appear to provide a sound estimate of the peak G force: only a limited insignificant correlation was found between peak G force and subject mass as well as mid-thigh perimeter and no correlation was found between peak G force and thigh length. The functional joint range of motion for human G muscle was determined to be at least as wide as full knee extension to 120 ° of knee flexion. However; the portion of the knee angle-muscle force relationship operationalized is not unique but individual specific: our data suggest for most subjects that G muscle operates in both ascending and descending limbs of its length-force characteristics whereas, for the remainder of the subjects, its function is limited to the descending limb, exclusively. Previous activity of G muscle at high muscle length attained during collection of a complete set of knee angle-force data showed for the first time that such length history effects are important also for human muscles: a significant correlation was found between optimal knee angle and absolute value of % force change. Except for two of the subjects, G muscle force measured at low length was lower than that measured during collection of knee joint-force data (maximally by 42.3%).
（1）测量之前未研究过的激活状态下人类股薄肌的等长力，作为膝关节角度的函数；（2）检验长度历史效应是否对人类肌肉也很重要。实验在膝关节前交叉韧带（ACL）重建手术过程中进行（n=8）。平均峰值股薄肌力、平均峰值股薄肌腱应力和平均最佳膝关节角度分别为 178.5±270.3N、24.4±20.6MPa 和 67.5±41.7 °。发现了大量的个体间变异性（例如，峰值股薄肌力范围在 17.2 到 490.5N 之间），这表明股薄肌对膝关节弯曲力矩的贡献可能在个体之间有很大差异。此外，典型的个体人体测量数据似乎不能很好地估计峰值股薄肌力：仅发现峰值股薄肌力与受试者体重以及大腿中部周长之间存在有限的无显著性相关性，而与大腿长度之间不存在相关性。确定人类股薄肌的功能关节活动范围至少与全膝关节伸展至 120°膝关节弯曲相同。然而，操作的膝关节角度-肌肉力关系部分不是唯一的，而是个体特异性的：我们的数据表明，对于大多数受试者，股薄肌在其长度-力特性的上升和下降支都起作用，而对于其余受试者，其功能仅限于下降支，完全如此。在收集完整的膝关节角度-力数据过程中，股薄肌在高肌肉长度下的先前活动首次表明，这种长度历史效应对人类肌肉也很重要：最佳膝关节角度与力变化绝对值之间存在显著相关性。除了两个受试者之外，在低长度时测量的股薄肌力都低于在收集膝关节力数据时测量的力（最大低 42.3%）。
