Lai Adrian, Lichtwark Glen A, Schache Anthony G, Lin Yi-Chung, Brown Nicholas A T, Pandy Marcus G
Department of Mechanical Engineering, University of Melbourne, Parkville, Victoria, Australia; Performance Science and Innovation, Australian Institute of Sport, Belconnen, Australian Capital Territory, Australia.
Centre for Sensorimotor Performance, The School of Human Movement Studies, The University of Queensland, St. Lucia, Queensland, Australia; and.
J Appl Physiol (1985). 2015 May 15;118(10):1266-75. doi: 10.1152/japplphysiol.00128.2015. Epub 2015 Mar 26.
The interaction between the muscle fascicle and tendon components of the human soleus (SO) muscle influences the capacity of the muscle to generate force and mechanical work during walking and running. In the present study, ultrasound-based measurements of in vivo SO muscle fascicle behavior were combined with an inverse dynamics analysis to investigate the interaction between the muscle fascicle and tendon components over a broad range of steady-state walking and running speeds: slow-paced walking (0.7 m/s) through to moderate-paced running (5.0 m/s). Irrespective of a change in locomotion mode (i.e., walking vs. running) or an increase in steady-state speed, SO muscle fascicles were found to exhibit minimal shortening compared with the muscle-tendon unit (MTU) throughout stance. During walking and running, the muscle fascicles contributed only 35 and 20% of the overall MTU length change and shortening velocity, respectively. Greater levels of muscle activity resulted in increasingly shorter SO muscle fascicles as locomotion speed increased, both of which facilitated greater tendon stretch and recoil. Thus the elastic tendon contributed the majority of the MTU length change during walking and running. When transitioning from walking to running near the preferred transition speed (2.0 m/s), greater, more economical ankle torque development is likely explained by the SO muscle fascicles shortening more slowly and operating on a more favorable portion (i.e., closer to the plateau) of the force-length curve.
人类比目鱼肌（SO）的肌束与肌腱成分之间的相互作用会影响该肌肉在步行和跑步过程中产生力量和机械功的能力。在本研究中，基于超声对活体SO肌束行为的测量与逆动力学分析相结合，以研究在广泛的稳态步行和跑步速度范围内（从慢步走（0.7米/秒）到中速跑（5.0米/秒））肌束与肌腱成分之间的相互作用。无论运动模式如何变化（即步行与跑步）或稳态速度如何增加，在整个站立期，与肌-腱单元（MTU）相比，SO肌束的缩短幅度都很小。在步行和跑步过程中，肌束分别仅占MTU总长度变化和缩短速度的35%和20%。随着运动速度的增加，更高水平的肌肉活动导致SO肌束越来越短，这两者都促进了肌腱更大程度的拉伸和回弹。因此，在步行和跑步过程中，弹性肌腱在MTU长度变化中占主要部分。当在接近首选过渡速度（2.0米/秒）时从步行过渡到跑步，SO肌束缩短更慢且在力-长度曲线更有利的部分（即更接近平台期）起作用，这可能解释了更经济地产生更大踝关节扭矩的原因。
