Leg muscles that mediate stability: mechanics and control of two distal extensor muscles during obstacle negotiation in the guinea fowl
Leg muscles that mediate stability: mechanics and control of two distal extensor muscles during obstacle negotiation in the guinea fowl
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DOI：
10.1098/rstb.2010.0338
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发表时间：
2011-05-27
影响因子：
6.3
通讯作者：
Biewener, Andrew A.
中科院分区：
文献类型：
--
作者：
Daley, Monica A.;Biewener, Andrew A.
在这里，我们使用障碍跑步机实验来研究不平坦地形中运动的神经肌肉控制。我们测量了珍珠鸡的两块远端肌肉、腓肠肌外侧肌 (LG) 和第四趾屈肌 (DF) 在水平跑步和两个不平坦地形（有 5 厘米和 7 厘米障碍物）期间的体内功能。地形不平坦，每四到五步就需要踏上一个障碍物。我们将不平坦地形和平坦地形中受扰动和不受扰动的步幅进行了比较。当鸟踩到障碍物时，腿会蹲下，两块肌肉的活动距离更长，产生的功更大，而且身体高度也会增加。 LG 跨过障碍跨步时肌肉激活增加，但 DF 没有，这表明 LG 的反射贡献更大。在不平坦地形中不受干扰地迈步时，与平坦地形相比，DF 的摆动预激活增加了 5%，这表明腿部阻抗的前馈调整。在不同条件下，两块肌肉之间工作输出的神经力学因素有所不同，这可能是由于肌肉肌腱结构的差异所致。 LG 功主要取决于束长度，而 DF 功取决于加载过程中的长度和速度。这些远端肌肉似乎通过快速感知和响应改变的腿部与地面相互作用而在稳定性方面发挥着关键作用。
Here, we used an obstacle treadmill experiment to investigate the neuromuscular control of locomotion in uneven terrain. We measured in vivo function of two distal muscles of the guinea fowl, lateral gastrocnemius (LG) and digital flexor-IV (DF), during level running, and two uneven terrains, with 5 and 7 cm obstacles. Uneven terrain required one step onto an obstacle every four to five strides. We compared both perturbed and unperturbed strides in uneven terrain to level terrain. When the bird stepped onto an obstacle, the leg became crouched, both muscles acted at longer lengths and produced greater work, and body height increased. Muscle activation increased on obstacle strides in the LG, but not the DF, suggesting a greater reflex contribution to LG. In unperturbed strides in uneven terrain, swing pre-activation of DF increased by 5 per cent compared with level terrain, suggesting feed-forward tuning of leg impedance. Across conditions, the neuromechanical factors in work output differed between the two muscles, probably due to differences in muscle-tendon architecture. LG work depended primarily on fascicle length, whereas DF work depended on both length and velocity during loading. These distal muscles appear to play a critical role in stability by rapidly sensing and responding to altered leg-ground interaction.