The subject-specific range of motion (RoM) of a musculoskeletal joint system is balanced by pre-tension levels of individual muscles, which affects their contraction capability. Such an inherent pre-tension or pre-stretch of muscles is not measureable with in vivo experiments. Using a 3D continuum mechanical forward simulation approach for motion analysis of the musculoskeletal system of the forearm with 3 flexor and 2 extensor muscles, we developed an optimization process to determine the muscle fibre pre-stretches for an initial arm position, which is given human dataset. We used RoM values of a healthy person to balance the motion in extension and flexion. The performed sensitivity study shows that the fibre pre-stretches of the m. brachialis, m. biceps brachii and m. triceps brachii with \(91\%\) dominate the objective flexion ratio, while m. brachiradialis and m. anconeus amount \(7.8\%\) and \(1.2\%\). Within the multi-dimensional space of the surrogate model, 3D sub-spaces of primary variables, namely the dominant muscles and the global objective, flexion ratio, exhibit a path of optimal solutions. Within this optimal path, the muscle fibre pre-stretch of two flexors demonstrate a negative correlation, while, in contrast, the primary extensor, m. triceps brachii correlates positively to each of the flexors. Comparing the global optimum with four other designs along the optimal path, we saw large deviations, e.g., up to 15\(^{\circ }\) in motion and up to 40% in muscle force. This underlines the importance of accurate determination of fibre pre-stretch in muscles, especially, their role in pathological muscular disorders and surgical applications such as free muscle or tendon transfer.

肌肉骨骼关节系统的特定受试者运动范围 (RoM) 通过各个肌肉的预张力水平进行平衡，这会影响其收缩能力。这种肌肉固有的预张力或预拉伸是无法通过体内实验测量的。使用 3D 连续机械正向模拟方法对具有 3 个屈肌和 2 个伸肌的前臂肌肉骨骼系统进行运动分析，我们开发了一个优化过程来确定初始手臂位置的肌纤维预拉伸，这是给定的人体数据集。我们使用健康人的 RoM 值来平衡伸展和弯曲的运动。进行的敏感性研究表明，米的纤维预拉伸。肱肌​肱二头肌和m。肱三头肌的\(91\%\)主导了目标屈曲比，而m。肱桡肌和m。肘节数量\(7.8\%\)和\(1.2\%\)。在代理模型的多维空间内，主要变量（即主导肌肉和全局目标屈曲比）的 3D 子空间展示了一条最优解的路径。在此最佳路径内，两个屈肌的肌纤维预拉伸表现出负相关，而相反，主要伸肌m 则呈负相关。肱三头肌与每个屈肌呈正相关。将全局最优值与最优路径上的其他四种设计进行比较，我们发现了很大的偏差，例如运动中高达 15 \(^{\circ }\)和肌肉力量高达 40%。这强调了准确测定肌肉中纤维预拉伸的重要性，特别是它们在病理性肌肉疾病和手术应用（例如游离肌肉或肌腱转移）中的作用。