Reilly Stephen M, McElroy Eric J, Biknevicius Audrone R
Department of Biological Sciences, Ohio University, Athens, OH 45701, USA.
Zoology (Jena). 2007;110(4):271-89. doi: 10.1016/j.zool.2007.01.003. Epub 2007 May 7.
A reanalysis of locomotor data from functional, energetic, mechanical and ecological perspectives reveals that limb posture has major effects on limb biomechanics, energy-saving mechanisms and the costs of locomotion. Regressions of data coded by posture (crouched vs. erect) reveal nonlinear patterns in metabolic cost, limb muscle mass, effective mechanical advantage, and stride characteristics. In small crouched animals energy savings from spring and pendular mechanisms are inconsequential and thus the metabolic cost of locomotion is driven by muscle activation costs. Stride frequency appears to be the principal functional parameter related to the decreasing cost of locomotion in crouched animals. By contrast, the shift to erect limb postures invoked a series of correlated effects on the metabolic cost of locomotion: effective mechanical advantage increases, relative muscle masses decrease, metapodial limb segments elongate dramatically (as limbs shift from digitigrade to unguligrade designs) and biological springs increase in size and effectiveness. Each of these factors leads to decreases in the metabolic cost of locomotion in erect forms resulting from real and increasing contributions of pendular savings and spring savings. Comparisons of the relative costs and ecological relevance of different gaits reveal that running is cheaper than walking in smaller animals up to the size of dogs but running is more expensive than walking in horses. Animals do not necessarily use their cheapest gaits for their predominant locomotor activity. Therefore, locomotor costs are driven more by ecological relevance than by the need to optimize locomotor economy.
从功能、能量、力学和生态学角度对运动数据进行的重新分析表明，肢体姿势对肢体生物力学、节能机制和运动成本有重大影响。按姿势（蹲伏与直立）编码的数据回归显示，代谢成本、肢体肌肉质量、有效力学优势和步幅特征存在非线性模式。在小型蹲伏动物中，弹簧和摆动机制节省的能量微不足道，因此运动的代谢成本由肌肉激活成本驱动。步频似乎是与蹲伏动物运动成本降低相关的主要功能参数。相比之下，向直立肢体姿势的转变对运动的代谢成本产生了一系列相关影响：有效力学优势增加，相对肌肉质量减少，跖骨肢体节段显著延长（随着肢体从趾行式设计转变为蹄行式设计），生物弹簧的大小和效能增加。这些因素中的每一个都导致直立形态的运动代谢成本降低，这是由于摆动节省和弹簧节省的实际贡献不断增加。对不同步态的相对成本和生态相关性的比较表明，在体型小至狗的动物中，奔跑比行走成本更低，但在马中，奔跑比行走成本更高。动物不一定会在其主要的运动活动中使用成本最低的步态。因此，运动成本更多地由生态相关性驱动，而不是由优化运动经济性的需求驱动。
