Takahashi Katsuki, Tozawa Hironoshin, Kawama Raki, Wakahara Taku
Faculty of Health and Sports Science, Doshisha University, Kyoto, Japan.
Graduate School of Health and Sports Science, Doshisha University, Kyoto, Japan.
J Appl Physiol (1985). 2025 Apr 1;138(4):1088-1099. doi: 10.1152/japplphysiol.00600.2024. Epub 2025 Mar 26.
Human leg muscles are uniquely enlarged for upright bipedalism, and the adductor magnus is one of the largest muscles. Although this muscle is recognized as a hip adductor, hip adduction torque is not greatly required during human locomotion, such as walking and running. The functional role of this giant muscle remains unclear. Here, we tested the hypothesis that the human adductor magnus acts primarily for hip extension rather than adduction in living young individuals. Utilizing diffusion tensor imaging, we reconstructed fascicles over the entire muscle in 15 young adults at the hip neutral position. We divided the muscle into three portions based on fascicle insertion and examined their three-dimensional architectures. The posterior and anterior-distal portions comprised over 80% of the whole muscle volume and physiological cross-sectional area. These portions demonstrated a longer moment arm for hip extension than adduction. Consequently, the potential torque (maximal torque-generating capacity) of the whole muscle was over twofold greater for hip extension than adduction. The hip extension potential torque was correlated with the maximal hip extension torque measured with a dynamometer. These results highlight the architectural design of the adductor magnus, favoring hip extension over adduction, providing novel insights into its functional role beyond the frontal plane in human locomotor mechanics. The human adductor magnus, one of the largest leg muscles, is traditionally considered a hip "adductor." However, its functional role is unclear. We found that the torque-generating capacity of this muscle for hip extension was substantially greater than that for hip adduction and explained the exerted torque for hip extension. Our findings highlight the important role of the adductor magnus as a major hip "extensor," having implications for mechanisms of human locomotion and musculoskeletal simulations.
人类腿部肌肉因直立双足行走而独特地增大，大收肌是最大的肌肉之一。尽管这块肌肉被认为是髋关节内收肌，但在人类行走和跑步等运动过程中，髋关节内收扭矩并非十分必要。这块巨大肌肉的功能作用仍不清楚。在此，我们测试了一个假设，即在活着的年轻人中，人类大收肌主要起髋关节伸展作用而非内收作用。利用扩散张量成像技术，我们在15名年轻成年人处于髋关节中立位时重建了整块肌肉的肌束。我们根据肌束附着点将肌肉分为三部分，并研究了它们的三维结构。后部分和前远侧部分占整个肌肉体积和生理横截面积的80%以上。这些部分显示出髋关节伸展的力臂比内收的力臂长。因此，整块肌肉的潜在扭矩（最大扭矩产生能力）用于髋关节伸展时比内收时大两倍多。髋关节伸展潜在扭矩与用测力计测量的最大髋关节伸展扭矩相关。这些结果突出了大收肌的结构设计，有利于髋关节伸展而非内收，为其在人类运动力学中额状面以外的功能作用提供了新的见解。人类大收肌是最大的腿部肌肉之一，传统上被认为是髋关节“内收肌”。然而，其功能作用尚不清楚。我们发现，这块肌肉产生髋关节伸展扭矩的能力远大于产生髋关节内收扭矩的能力，并解释了髋关节伸展时所施加的扭矩。我们的研究结果突出了大收肌作为主要髋关节“伸肌”的重要作用，对人类运动机制和肌肉骨骼模拟具有重要意义。
