According to the force-length-velocity relationships, the muscle force potential during locomotion is determined by the operating fibre length and velocity. We measured fascicle and muscle-tendon unit length and velocity as well as the activity of the human vastus lateralis muscle (VL) during walking and running. Furthermore, we determined the VL force-length relationship experimentally and calculated the force-length and force-velocity potentials (i.e. fraction of maximum force according to the force-length-velocity curves) for both gaits. During the active state of the stance phase, fascicles showed significantly (p < 0.05) smaller length changes (walking: 9.2 ± 4.7% of optimal length (L₀); running: 9.0 ± 8.4%L₀) and lower velocities (0.46 ± 0.36 L₀/s; 0.03 ± 0.83 L₀/s) compared to the muscle-tendon unit (walking: 19.7 ± 5.3%L₀, -0.94 ± 0.32 L₀/s; running: 34.5 ± 5.8%L₀, -2.59 ± 0.41 L₀/s). The VL fascicles operated close to optimum length (L₀ = 9.4 ± 0.11 cm) in both walking (8.6 ± 0.14 cm) and running (10.1 ± 0.19 cm), resulting in high force-length (walking: 0.92 ± 0.08; running: 0.91 ± 0.14) and force-velocity (0.91 ± 0.08; 0.97 ± 0.13) potentials. For the first time we demonstrated that, in contrast to the current general conception, the VL fascicles operate almost isometrically and close to L₀ during the active state of the stance phase of walking and running. The findings further verify an important contribution of the series-elastic element to VL fascicle dynamics.

中文翻译：

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步行和跑步时人体股外侧肌的工作长度和速度。


根据力-长度-速度关系，运动过程中的肌肉力势由操作纤维长度和速度决定。我们测量了肌束和肌腱单位长度和速度，以及步行和跑步期间人体股外侧肌 (VL) 的活动。此外，我们通过实验确定了 VL 力-长度关系，并计算了两种步态的力-长度和力-速度势（即根据力-长度-速度曲线的最大力的分数）。在站立阶段的活动状态期间，束显示出显着（p < 0.05）较小的长度变化（步行：最佳长度（L ₀ ）的 9.2 ± 4.7%；跑步：9.0 ± 8.4%L ₀ ）和较低的速度（0.46 ± 0.36 L ₀ /s；0.03 ± 0.83 L ₀ /s）与肌肉肌腱单元相比（步行：19.7 ± 5.3%L ₀ , -0.94 ± 0.32 L ₀ /s；跑步：34.5 ± 5.8%L ₀ , - 2.59 ± 0.41 L ₀ /秒）。 VL 束在步行 (8.6 ± 0.14 cm) 和跑步 (10.1 ± 0.19 cm) 中均接近最佳长度 (L ₀ = 9.4 ± 0.11 cm)，从而产生较高的力长度（步行：0.92 ± 0.08；跑步： 0.91 ± 0.14) 和力-速度 (0.91 ± 0.08; 0.97 ± 0.13) 势。我们首次证明，与当前的一般概念相反，VL 束在行走和跑步的站立阶段的活跃状态下几乎等长地运行且接近 L ₀ 。研究结果进一步证实了串联弹性元件对 VL 束动力学的重要贡献。