Moreno Carlos A, Main Russell P, Biewener Andrew A
Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, 100 Old Causeway Road, Bedford, MA 01730, USA.
J Exp Biol. 2008 Apr;211(Pt 7):1148-62. doi: 10.1242/jeb.012419.
The purpose of this study was to investigate the effects of non-steady locomotor activities on load predictability in two goat forelimb bones and to explore the degree to which bone curvature influences load predictability. We measured in vivo bone strains in the radius and metacarpus of juvenile goats performing a variety of natural behaviors in an outdoor arena and compared these strain magnitudes and loading patterns with those measured during steady-state treadmill locomotion. We sought to test two hypotheses: our first hypothesis expects an increase in the variability of strain magnitude and pattern during outdoor non-steady behavior when compared to treadmill locomotion. Our second hypothesis was that the curved radius experiences higher peak strains but less variability during non-steady activities than the straighter metacarpus. We found that unsteady, outdoor locomotion generally caused more variable strain patterns (consistent with the first hypothesis), but not more variable strain magnitudes, than treadmill locomotion in both bones. During outdoor locomotion, higher magnitude strain events in the radius showed more constrained loading patterns than in the metacarpus (consistent with the second hypothesis). In addition to the radius experiencing significantly greater bending strains compared to the straighter metacarpus, these results support the idea of a trade-off between increased predictability of loading pattern and increased bending-induced strain. Strain magnitudes recorded during both outdoor and treadmill locomotion showed a lognormal frequency distribution, but the outdoor bone strain distributions had a greater range because they included high magnitude loading events that did not occur during steady treadmill locomotion.
本研究的目的是调查非稳态运动活动对两只山羊前肢骨骼负荷可预测性的影响，并探究骨骼曲率对负荷可预测性的影响程度。我们测量了幼年山羊在户外场地进行各种自然行为时桡骨和掌骨的体内骨应变，并将这些应变大小和加载模式与在稳态跑步机运动期间测量的结果进行比较。我们试图检验两个假设：我们的第一个假设预计，与跑步机运动相比，户外非稳态行为期间应变大小和模式的变异性会增加。我们的第二个假设是，在非稳态活动期间，弯曲的桡骨比更直的掌骨经历更高的峰值应变，但变异性更小。我们发现，与跑步机运动相比，不稳定的户外运动通常会导致更具变异性的应变模式（与第一个假设一致），但应变大小的变异性并不更大，在两根骨骼中均如此。在户外运动期间，桡骨中更高大小的应变事件显示出比掌骨更受限制的加载模式（与第二个假设一致）。除了桡骨与更直的掌骨相比经历了明显更大的弯曲应变外，这些结果支持了在加载模式可预测性增加与弯曲诱导应变增加之间进行权衡的观点。在户外和跑步机运动期间记录的应变大小均呈现对数正态频率分布，但户外骨应变分布的范围更大，因为它们包括了在稳态跑步机运动期间未出现的高大小加载事件。
