Contralateral movement and extensor force generation alter flexion phase muscle coordination in pedaling.
Contralateral movement and extensor force generation alter flexion phase muscle coordination in pedaling.
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DOI：
10.1152/jn.2000.83.6.3351
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发表时间：
2000-06
影响因子：
2.5
通讯作者：
Lena H. Ting;Steven A. Kautz;David A. Brown;Felix E. Zajac
中科院分区：
文献类型：
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作者：
Lena H. Ting;Steven A. Kautz;David A. Brown;Felix E. Zajac
双侧感觉运动信号在协调运动中的重要性已在动物中得到证实，但由于腿之间力的机械传递的混淆效应（即，机械腿间耦合）。在以前的蹬踏研究中，通过消除机械腿间耦合，我们表明，肌肉协调的单足任务可以塑造肢体间感觉运动通路。肢体间神经通路被证明可以改变踩踏协调，因为与双侧踩踏相比，单侧踩踏显示出增加的屈曲相肌肉活动，即使单侧和双侧踩踏任务中踩踏腿执行的任务力学是相同的。为了进一步研究对侧感觉运动状态和同侧屈曲相肌肉协调之间的关系，在本研究中，受试者用一条腿踩踏板，而对侧腿要么产生伸肌力，要么放松，因为伸肌要么保持腿静止，要么与踩踏腿反相移动。在对侧伸肌力量产生的存在下，在肢体屈曲过程中，蹬踏腿的肌肉活动减少。在屈曲过程中，无论非蹬踏腿产生的力的幅度如何，也无论腿是静止还是运动，蹬踏腿腿的腘绳肌（股二头肌和半膜肌）的综合肌电图活动都会降低25- 30%。相反，只有当对侧腿产生高节奏的力量伴随着腿的运动时，屈曲过程中股直肌和胫骨前肌的活动才会减少。结果是一致的对侧前馈机制触发屈曲相腘绳肌活动和对侧反馈机制调制股直肌和胫骨前肌活动在屈曲。由于只观察到有助于屈曲作为次要功能的肌肉，因此不可能知道调节作用是否也作用于主要的单功能肢体屈肌或特异于有助于屈曲的多功能肌肉。对侧伸肌相位感觉运动信号对同侧屈曲的影响可能反映了增益控制机制的双侧耦合。更一般地，这些肢体间神经机制可以协调在身体的相对侧上执行对抗功能的肌肉之间的活动。由于踩踏板和步行共享生物力学和神经元控制特征，这些机制可能在步行和踩踏板中起作用。
The importance of bilateral sensorimotor signals in coordination of locomotion has been demonstrated in animals but is difficult to ascertain in humans due to confounding effects of mechanical transmission of forces between the legs (i.e., mechanical interleg coupling). In a previous pedaling study, by eliminating mechanical interleg coupling, we showed that muscle coordination of a unipedal task can be shaped by interlimb sensorimotor pathways. Interlimb neural pathways were shown to alter pedaling coordination as subjects pedaling unilaterally exhibited increased flexion-phase muscle activity compared with bilateral pedaling even though the task mechanics performed by the pedaling leg(s) in the unilateral and bilateral pedaling tasks were identical. To further examine the relationship between contralateral sensorimotor state and ipsilateral flexion-phase muscle coordination during pedaling, subjects in this study pedaled with one leg while the contralateral leg either generated an extensor force or relaxed as a servomotor either held that leg stationary or moved it in antiphase with the pedaling leg. In the presence of contralateral extensor force generation, muscle activity in the pedaling leg during limb flexion was reduced. Integrated electromyographic activity of the pedaling-leg hamstring muscles (biceps femoris and semimembranosus) during flexion decreased by 25-30%, regardless of either the amplitude of force generated by the nonpedaling leg or whether the leg was stationary or moving. In contrast, rectus femoris and tibialis anterior activity during flexion decreased only when the contralateral leg generated high rhythmic force concomitant with leg movement. The results are consistent with a contralateral feedforward mechanism triggering flexion-phase hamstrings activity and a contralateral feedback mechanism modulating rectus femoris and tibialis anterior activity during flexion. Because only muscles that contribute to flexion as a secondary function were observed, it is impossible to know whether the modulatory effect also acts on primary, unifunctional, limb flexors or is specific to multifunctional muscles contributing to flexion. The influence of contralateral extensor-phase sensorimotor signals on ipsilateral flexion may reflect bilateral coupling of gain control mechanisms. More generally, these interlimb neural mechanisms may coordinate activity between muscles that perform antagonistic functions on opposite sides of the body. Because pedaling and walking share biomechanical and neuronal control features, these mechanisms may be operational in walking as well as pedaling.