Contributions of the individual ankle plantar flexors to support, forward progression and swing initiation during walking
Contributions of the individual ankle plantar flexors to support, forward progression and swing initiation during walking
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DOI：
10.1016/s0021-9290(01)00105-1
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发表时间：
2001-11-01
影响因子：
2.4
通讯作者：
Zajac, FE
中科院分区：
文献类型：
--
作者：
Neptune, RR;Kautz, SA;Zajac, FE
步行是一项需要许多肌肉协调的运动任务。先前的生物力学研究主要基于对站立期间的净踝力矩的分析，得出了跖屈肌的不同功能作用的结论。我们假设解释中的一些差异是由于构成跖屈肌群的单关节和双关节肌肉的影响尚未分开而引起的。此外，我们认为，准确确定肌肉功能需要量化各个跖屈肌对各个身体部位能量的贡献。在这项研究中，我们使用肌肉骨骼模型和优化框架检查了踝关节跖屈肌（腓肠肌 (GAS)；比目鱼肌 (SOL)）对身体节段能量学的个体贡献，以生成 1.5 m/s 正常行走的正向动力学模拟。在步态周期的任何时刻，肌肉对支撑和向前进展的贡献分别由其对躯干垂直和水平加速度的贡献以及其在摆动前（即脚趾离地前的双腿站立）传递到腿部的机械能对摆动起始的贡献来定义。研究发现 GAS 和 SOL 在单腿站立和预挥杆期间提供躯干支撑。在早期的单腿站立中，进行离心和等长活动时，它们会加速躯干垂直方向，但会减慢躯干向前前进的速度。在中等单腿站立时，当等长时，GAS 向腿部提供能量，而 SOL 使其减速，SOL 向躯干提供能量，同时 GAS 使其减速。在单腿站立后期到挥杆前，虽然 GAS 和 SOL 都经历同心活动并加速躯干向前，同时减速躯干向下运动（即提供向前推进和支撑），但它们执行不同的能量功能。 SOL 产生的能量使躯干向前加速，而 GAS 则提供几乎所有的能量来加速腿部启动摆动。尽管 GAS 和 SOL 在单腿站立中部通过预摆动维持或加速向前运动，但在站立开始时起作用的其他肌肉对向前进展的贡献相当。总之，在整个单腿站立过程中，SOL 和 GAS 都提供垂直支撑，在单腿站立中期，SOL 和 GAS 对腿部和躯干产生相反的能量影响，以确保腿部和躯干的支撑和向前推进，而在挥杆前，只有 GAS 有助于挥杆启动。 (C) 2001 Elsevier Science Ltd. 保留所有权利。
Walking is a motor task requiring coordination of many muscles. Previous biomechanical studies, based primarily on analyses of the net ankle moment during stance, have concluded different functional roles for the plantar flexors. We hypothesize that some of the disparities in interpretation arise because of the effects of the uniarticular and biarticular muscles that comprise the plantar flexor group have not been separated. Furthermore, we believe that an accurate determination of muscle function requires quantification of the contributions of individual plantar flexor muscles to the energetics of individual body segments. In this study, we examined the individual contributions of the ankle plantar flexors (gastrocnemius (GAS); soleus (SOL)) to the body segment energetics using a musculoskeletal model and optimization framework to generate a forward dynamics simulation of normal walking at 1.5 m/s. At any instant in the gait cycle, the contribution of a muscle to support and forward progression was defined by its contribution to trunk vertical and horizontal acceleration, respectively, and its contribution to swing initiation by the mechanical energy it delivers to the leg in pre-swing (i.e., double-leg stance prior to toe-off). GAS and SOL were both found to provide trunk support during single-leg stance and pre-swing. In early single-leg stance, undergoing eccentric and isometric activity, they accelerate the trunk vertically but decelerate forward trunk progression. In mid single-leg stance, while isometric, GAS delivers energy to the leg while SOL decelerates it, and SOL delivers energy to the trunk while GAS decelerates it. In late single-leg stance through pre-swing, though GAS and SOL both undergo concentric activity and accelerate the trunk forward while decelerating the downward motion of the trunk (i.e., providing forward progression and support), they execute different energetic functions. The energy produced from SOL accelerates the trunk forward, whereas GAS delivers almost all its energy to accelerate the leg to initiate swing. Although GAS and SOL maintain or accelerate forward motion in mid single-leg stance through pre-swing, other muscles acting at the beginning of stance contribute comparably to forward progression. In summary, throughout single-leg stance both SOL and GAS provide vertical support, in mid single-leg stance SOL and GAS have opposite energetic effects on the leg and trunk to ensure support and forward progression of both the leg and trunk, and in pre-swing only GAS contributes to swing initiation. (C) 2001 Elsevier Science Ltd. All rights reserved.