Muscle mechanical advantage of human walking and running: implications for energy cost
Muscle mechanical advantage of human walking and running: implications for energy cost
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DOI：
10.1152/japplphysiol.00003.2004
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发表时间：
2004-12-01
影响因子：
3.3
通讯作者：
Temaner, M
中科院分区：
文献类型：
--
作者：
Biewener, AA;Farley, CT;Temaner, M
在运动过程中产生的肌肉力量取决于动物的速度、步态和大小，并且是驱动运动的能量需求的基础。肢体姿势的变化通过改变地面反作用力（R）的机械效益以及因此肌肉力量产生的有效机械效益（EMA = r/R，其中r是肌肉机械效益）来影响肌肉力量。我们使用了基于测力板和人类运动学记录的逆动力学，因为他们以稳定的速度行走和跑步，以研究肌肉EMA的变化如何影响这些步态的肌肉力量产生要求。我们发现，当人类将步态从步行改变为跑步时，膝伸肌EMA减少68%，而髋伸肌EMA增加18%，踝伸肌EMA增加23%。在行走的大部分支撑阶段，膝关节伸展（154 - 176度），而在跑步过程中，其屈曲位置（134 - 164度）导致四头肌冲动（站立时的时间积分力）增加5.2倍，需要在地面上支撑体重。这种增加与膝关节周围的地面反作用力力矩增加4.9倍有关。相比之下，当受试者从步行转换为跑步时，髋关节的伸肌冲动下降了37%（P < 0.05），踝关节的伸肌冲动没有变化。我们的结论是，肢体机械优势（平均肢体伸肌EMA）的减少和增加膝伸肌冲动在运行过程中可能有助于更高的代谢成本的运输比步行。跑步的人的低机械优势也可以解释以前的观察，即跑步的人与小跑和疾驰的类似大小的四足动物相比，运输的代谢成本更大。
Muscular forces generated during locomotion depend on an animal's speed, gait, and size and underlie the energy demand to power locomotion. Changes in limb posture affect muscle forces by altering the mechanical advantage of the ground reaction force ( R) and therefore the effective mechanical advantage (EMA = r/R, where r is the muscle mechanical advantage) for muscle force production. We used inverse dynamics based on force plate and kinematic recordings of humans as they walked and ran at steady speeds to examine how changes in muscle EMA affect muscle force-generating requirements at these gaits. We found a 68% decrease in knee extensor EMA when humans changed gait from a walk to a run compared with an 18% increase in hip extensor EMA and a 23% increase in ankle extensor EMA. Whereas the knee joint was extended ( 154 - 176degrees) during much of the support phase of walking, its flexed position ( 134 - 164degrees) during running resulted in a 5.2-fold increase in quadriceps impulse (time-integrated force during stance) needed to support body weight on the ground. This increase was associated with a 4.9-fold increase in the ground reaction force moment about the knee. In contrast, extensor impulse decreased 37% ( P < 0.05) at the hip and did not change at the ankle when subjects switched from a walk to a run. We conclude that the decrease in limb mechanical advantage ( mean limb extensor EMA) and increase in knee extensor impulse during running likely contribute to the higher metabolic cost of transport in running than in walking. The low mechanical advantage in running humans may also explain previous observations of a greater metabolic cost of transport for running humans compared with trotting and galloping quadrupeds of similar size.