Neptune R R, Kautz S A, Zajac F E
Rehabilitation R & D Center, VA Palo Alto Health Care System, CA 94304, USA.
J Biomech. 2000 Feb;33(2):155-64. doi: 10.1016/s0021-9290(99)00150-5.
Previous work had identified six biomechanical functions that need to be executed by each limb in order to produce a variety of pedaling tasks. The functions can be organized into three antagonistic pairs: an Ext/Flex pair that accelerates the foot into extension or flexion with respect to the pelvis, an Ant/Post pair that accelerates the foot anteriorly or posteriorly with respect to the pelvis, and a Plant/Dorsi pair that accelerates the foot into plantarflexion or dorsiflexion. Previous analyses of experimental data have inferred that muscles perform the same function during different pedaling tasks (e.g. forward versus backward pedaling) because the EMG timing was similar, but they did not present rigorous biomechanical analyses to assess whether a muscle performed the same biomechanical function, and if so, to what degree. Therefore, the objective of this study was to determine how individual muscles contribute to these biomechanical functions during two different motor tasks, forward and backward pedaling, through a theoretical analysis of experimental data. To achieve this objective, forward and backward pedaling simulations were generated and a mechanical energy analysis was used to examine how muscles generate, absorb or transfer energy to perform the pedaling tasks. The results showed that the muscles contributed to the same primary Biomechanical functions in both pedaling directions and that synergistic performance of certain functions effectively accelerated the crank. The gluteus maximus worked synergistically with the soleus, the hip flexors worked synergistically with the tibialis anterior, and the vasti and hamstrings functioned independently to accelerate the crank. The rectus femoris used complex biomechanical mechanisms including negative muscle work to accelerate the crank. The negative muscle work was used to transfer energy generated elsewhere (primarily from other muscles) to the pedal reaction force in order to accelerate the crank. Consistent with experimental data, a phase shift was required from those muscles contributing to the Ant/Post functions as a result of the different limb kinematics between forward and backward pedaling, although they performed the same biomechanical function. The pedaling simulations proved necessary to interpret the experimental data and identify motor control mechanisms used to accomplish specific motor tasks, as the mechanisms were often complex and not always intuitively obvious.
先前的研究已经确定了六种生物力学功能，每个肢体都需要执行这些功能才能完成各种蹬踏任务。这些功能可分为三对拮抗肌：一对伸肌/屈肌，使足部相对于骨盆加速伸展或屈曲；一对前肌/后肌，使足部相对于骨盆向前或向后加速；一对跖肌/背肌，使足部加速跖屈或背屈。先前对实验数据的分析推断，在不同的蹬踏任务（如向前与向后蹬踏）中，肌肉执行相同的功能，因为肌电图的时间相似，但他们没有进行严格的生物力学分析来评估一块肌肉是否执行相同的生物力学功能，如果是，程度如何。因此，本研究的目的是通过对实验数据的理论分析，确定在向前和向后蹬踏这两种不同的运动任务中，单个肌肉如何对这些生物力学功能做出贡献。为了实现这一目标，生成了向前和向后蹬踏的模拟，并使用机械能分析来研究肌肉如何产生、吸收或传递能量以完成蹬踏任务。结果表明，在两个蹬踏方向上，肌肉对相同的主要生物力学功能做出了贡献，并且某些功能的协同作用有效地加速了曲柄。臀大肌与比目鱼肌协同工作，髋屈肌与胫骨前肌协同工作，股四头肌和腘绳肌独立发挥作用以加速曲柄。股直肌使用复杂的生物力学机制，包括负向肌肉功来加速曲柄。负向肌肉功用于将其他地方产生的能量（主要来自其他肌肉）传递到踏板反作用力，以加速曲柄。与实验数据一致，由于向前和向后蹬踏之间肢体运动学的不同，对前肌/后肌功能有贡献的那些肌肉需要有一个相移，尽管它们执行相同的生物力学功能。蹬踏模拟被证明对于解释实验数据和识别用于完成特定运动任务的运动控制机制是必要的，因为这些机制通常很复杂，并不总是直观明显的。
