The cost of walking downhill: Is the preferred gait energetically optimal?
The cost of walking downhill: Is the preferred gait energetically optimal?
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DOI：
10.1016/j.jbiomech.2010.03.030
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发表时间：
2010-07-20
影响因子：
2.4
通讯作者：
Dean, J. C.
中科院分区：
文献类型：
--
作者：
Hunter, L. C.;Hendrix, E. C.;Dean, J. C.
人类倾向于选择能量消耗最小的步行方式，但也必须保持稳定以避免摔倒。这两个目标在确定首选步态模式中的相对重要性目前尚不清楚。我们研究了下坡行走时能量消耗和稳定性之间的关系，在这种情况下，重力能量有助于推进，但也可能降低稳定性。我们假设人类在下坡行走时不会将能量消耗最小化，而是更喜欢一种增加稳定性的步态模式。通过对动态步行模型的仿真，确定了采用简单的控制策略是否可以实现稳定的下坡步态。实验中，12名健康受试者以1.25 m/s（0、0.05、0.10和0.15梯度）的速度下坡。对于每个斜坡，受试者进行正常和放松的试验，他们被指示减少肌肉活动，并允许重力最大限度地帮助他们的步态。我们量化了能量消耗、步幅时间和腿部肌肉活动。在我们的模型模拟中，坡度的增加减少了所需的驱动，但也降低了稳定性。实验对象在使用放松步行策略时比使用正常步行策略时更像模型；放松策略降低了陡坡上的能量消耗，但增加了步幅周期变异性，这是一个不稳定的指标。这些结果表明，受试者并没有充分利用重力提供的推进力来减少能量消耗，而是更倾向于一种更稳定、更昂贵的步态模式。(C) 2010 Elsevier Ltd.版权所有。
Humans tend to prefer walking patterns that minimize energetic cost, but must also maintain stability to avoid falling over. The relative importance of these two goals in determining the preferred gait pattern is not currently clear. We investigated the relationship between energetic cost and stability during downhill walking, a context in which gravitational energy will assist propulsion but may also reduce stability. We hypothesized that humans will not minimize energetic cost when walking downhill, but will instead prefer a gait pattern that increases stability. Simulations of a dynamic walking model were used to determine whether stable downhill gaits could be achieved using a simple control strategy. Experimentally, twelve healthy subjects walked downhill at 1.25 m/s (0, 0.05, 0.10, and 0.15 gradients). For each slope, subjects performed normal and relaxed trials, in which they were instructed to reduce muscle activity and allow gravity to maximally assist their gait. We quantified energetic cost, stride timing, and leg muscle activity. In our model simulations, increase in slope reduced the required actuation but also decreased stability. Experimental subjects behaved more like the model when using the relaxed rather than the normal walking strategy; the relaxed strategy decreased energetic cost at the steeper slopes but increased stride period variability, an indicator of instability. These results indicate that subjects do not take optimal advantage of the propulsion provided by gravity to decrease energetic cost, but instead prefer a more stable and more costly gait pattern. (C) 2010 Elsevier Ltd. All rights reserved.