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首页> 外文期刊>Journal of Neurophysiology >Phase reversal of biomechanical functions and muscle activity in backward pedaling.
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Phase reversal of biomechanical functions and muscle activity in backward pedaling.

机译：向后踩踏过程中生物力学功能和肌肉活动的相位反转。

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摘要

Computer simulations of pedaling have shown that a wide range of pedaling tasks can be performed if each limb has the capability of executing six biomechanical functions, which are arranged into three pairs of alternating antagonistic functions. An Ext/Flex pair accelerates the limb into extension or flexion, a Plant/Dorsi pair accelerates the foot into plantarflexion or dorsiflexion, and an Ant/Post pair accelerates the foot anteriorly or posteriorly relative to the pelvis. Because each biomechanical function (i.e., Ext, Flex, Plant, Dorsi, Ant, or Post) contributes to crank propulsion during a specific region in the cycle, phasing of a muscle is hypothesized to be a consequence of its ability to contribute to one or more of the biomechanical functions. Analysis of electromyogram (EMG) patterns has shown that this biomechanical framework assists in the interpretation of muscle activity in healthy and hemiparetic subjects during forward pedaling. Simulations show that backward pedaling can be produced with a phase shift of 180 degrees in the Ant/Post pair. No phase shifts in the Ext/Flex and Plant/Dorsi pairs are then necessary. To further test whether this simple yet biomechanically viable strategy may be used by the nervous system, EMGs from 7 muscles in 16 subjects were measured during backward as well as forward pedaling. As predicted, phasing in vastus medialis (VM), tibialis anterior (TA), medial gastrocnemius (MG), and soleus (SL) were unaffected by pedaling direction, with VM and SL contributing to Ext, MG to Plant, and TA to Dorsi. In contrast, phasing in biceps femoris (BF) and semimembranosus (SM) were affected by pedaling direction, as predicted, compatible with their contribution to the directionally sensitive Post function. Phasing of rectus femoris (RF) was also affected by pedaling direction; however, its ability to contribute to the directionally sensitive Ant function may only be expressed in forward pedaling. RF also contributed significantly to the directionally insensitive Ext function in both forward and backward pedaling. Other muscles also appear to have contributed to more than one function, which was especially evident in backward pedaling (i.e. , BF, SM, MG, and TA to Flex). We conclude that the phasing of only the Ant and Post biomechanical functions are directionally sensitive. Further, we suggest that task-dependent modulation of the expression of the functions in the motor output provides this biomechanics-based neural control scheme with the capability to execute a variety of lower limb tasks, including walking.
机译：踩踏的计算机模拟表明，如果每个肢体都具有执行六种生物力学功能的能力，则可以执行多种踩踏任务，这些功能分为三对交替的对抗功能。 Ext / Flex对加速肢体伸展或屈曲，Plant / Dorsi对使脚加速使其足底屈曲或背屈，而Ant / Post对使脚相对于骨盆向前或向后加速。由于每种生物力学功能（即Ext，Flex，Plant，Dorsi，Ant或Post）在循环的特定区域内都有助于曲柄推进，因此肌肉的定相被认为是其贡献能力的结果。更多的生物力学功能。肌电图（EMG）模式的分析表明，这种生物力学框架有助于在向前踩踏过程中对健康和偏瘫患者的肌肉活动进行解释。仿真表明，在蚂蚁/后哨对中，可以以180度的相移产生向后踩踏板。这样就无需在Ext / Flex和Plant / Dorsi对中进行相移。为了进一步测试这种简单但生物力学上可行的策略是否可以被神经系统使用，在向前和向后踩踏过程中对16位受试者的7条肌肉的肌电图进行了测量。如预期的那样，踩踏方向的位置不受股内侧肌（VM），胫前肌（TA），腓肠肌内侧（MG）和比目鱼肌（SL）的影响，VM和SL有助于Ext，MG有助于Plant，TA有助于Dorsi 。相反，股二头肌（BF）和半膜肌（SM）的定相受踩踏方向的影响，如预期的那样，与其对方向性敏感Post功能的贡献相适应。股直肌（RF）的阶段也受踏板方向的影响;然而，其对方向敏感的蚂蚁功能有贡献的能力只能在向前踩踏时表达。射频在向前和向后踩踏时也对方向不敏感的Ext功能做出了重要贡献。其他肌肉似乎也贡献了不止一种功能，这在向后踩踏时尤其明显（即BF，SM，MG和TA到Flex）。我们得出的结论是，仅Ant和Post生物力学功能的定相是方向敏感的。此外，我们建议对马达输出中的功能表达进行与任务有关的调制，从而为这种基于生物力学的神经控制方案提供执行多种下肢任务（包括行走）的能力。

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