Simulation analysis of muscle activity changes with altered body orientations during pedaling.
Simulation analysis of muscle activity changes with altered body orientations during pedaling.
复制标题
模拟分析踩踏过程中身体方向改变时肌肉活动的变化。
DOI：
10.1016/s0021-9290(01)00014-8
复制
发表时间：
2001
影响因子：
2.4
通讯作者：
Zajac,FE
中科院分区：
文献类型：
--
作者：
Chen,G;Kautz,SA;Zajac,FE
对于大多数运动任务（如行走），测试与重力方向对神经控制机制的影响相关的假设是困难的，因为相对于重力的身体方向会影响感觉运动控制和任务机制。为了独立于工作量和姿势的变化来检查身体方向的机械效应，Brown等人（J. Biomech. 29 p.1349，1996）研究了在改变的身体取向下的踩踏。他们发现，以不同方向踩踏板的受试者不必要地改变了他们的肌肉兴奋，这是为了保持身体直立踩踏板的运动学。我们测试了这一假设的可行性，使用模拟的基础上的三个生物力学功能对组织控制下肢肌肉（肢体伸展/屈曲对，伸展/屈曲过渡对，足跖屈/背屈对），其中每对交替的激动/拮抗肌肉。调整只有三个参数，一个规模的肌肉兴奋的每一对，足以保持踩踏运动改变身体的方向。因为这些调整产生的肌肉兴奋和净关节力矩的变化类似于在踩踏受试者中观察到的变化，所以该假设得到了支持。此外，解耦增益调整过程的有效性，其中在每次迭代期间，每个参数仅在踩踏轨迹的一个方面（即，节奏调整了Ext/Flex参数;在周期内曲柄速度的峰到峰变化调整了过渡参数;在周期内平均踝关节角度调整了足部参数）进一步支持了每个肌肉对的不同功能。
Testing hypotheses related to the effect of gravitational orientation on neural control mechanisms is difficult for most locomotor tasks, like walking, because body orientation with respect to gravity affects both sensorimotor control and task mechanics. To examine the mechanical effect of body orientation independently from changes in workload and posture, Brown et al. (J. Biomech. 29 p. 1349, 1996) studied pedaling at altered body orientations. They found that subjects pedaling at different orientations changed needlessly their muscle excitations, putatively to preserve body-upright pedaling kinematics. We tested the feasibility of this hypothesis using simulations based on a three biomechanical-function pair organization for control of lower limb muscles (limb extension/flexion pair, extension/flexion transition pair, and foot plantarflexion/dorsiflexion pair), where each pair consists of alternating agonistic/antagonistic muscles. Adjustment of only three parameters, one to scale the muscle excitations of each pair, was sufficient to preserve pedaling kinematics to altered body orientation. Because these adjustments produced changes in muscle excitation and net joint moments similar to those observed in pedaling subjects, the hypothesis is supported. Moreover, the effectiveness of a decoupled gain adjustment procedure where each parameter was adjusted by error in only one aspect of the pedaling trajectory during each iteration (i.e., cadence adjusted the Ext/Flex parameter; peak-to-peak variation in crank velocity over the cycle adjusted the transition parameter; average ankle angle over the cycle adjusted the foot parameter) further supports the distinct function of each muscle pair.