Doctoral Dissertation Improvement Grant: The Effect of Hindlimb Length on Running and Walking Performance

尽管对运动能量学进行了数十年的研究，但腿长在决定运动能量效率和速度方面的作用仍然不清楚。本项目将研究腿长对人类和家犬行走和跑步过程中能量成本和速度的影响，以测试一种新的生物力学模型，该模型将腿长作为这些性能变量的决定因素。在跑步机试验期间，将测量这两个物种在不同步行和跑步速度范围内的能量消耗。还将进行一系列户外试验，以测试腿长对最大跑步速度和加速度的影响，并调查能量效率与最大速度和加速度之间的权衡。结果将被用来测试该模型的预测，具体地说，增加腿长可以提高行走和跑步时的能量效率和速度，但代价是减少加速度和增加摆动腿所需的能量。包括两足动物(人类)和四足动物(狗)将进一步提供一种方法，通过一系列解剖设计来研究腿长度和运动性能之间的联系。如果成功，该模型将通过提供一种新的、可能更准确和可靠的方法来推断运动行为和进化，从而为定量评估生物和化石物种的运动能力提供一种新的方法。由于人类属的进化以腿长的显著增加为标志，该模型将特别有助于检验目前关于原始人运动和觅食行为进化的假说。鉴于现存和灭绝物种运动适应的多样性，无法根据肢体设计可靠和定量地预测运动性能，这是我们对运动适应和生态学理解的一个重大缺陷。这项研究将通过测试一个相对简单的模型来解决这个问题，该模型明确地将腿部长度作为运动能量成本的决定因素，并测试腿部长度对最大速度和首选速度的影响。该项目还将促进身体人类学研究生培养和研究与实验生理学和生物力学相结合。

Despite decades of research on locomotor energetics, the role of leg length in determining locomotor energy efficiency and speed remains unclear. This project will investigate the effect of leg length on energy cost and speed during walking and running in human and domestic dogs in order to test a new biomechanical model that incorporates leg length as a determinant of these performance variables. Energy expenditure will be measured at a range of walking and running speeds for both species during treadmill trials. A set of outdoor trials will also be conducted in order to test the effect of leg length on maximum running speed and acceleration, and to investigate tradeoffs between energetic efficiency and maximum speed and acceleration. Results will be used to test predictions of the model, specifically that increased leg length improves energy efficiency and speed during walking and running, but at the cost of decreased acceleration and increased energy necessary to swing the leg. The inclusion of both bipeds (humans) and quadrupeds (dogs) will further provide a means of investigating the link between leg length and locomotor performance across a range of anatomical design. If successful, the model will provide a new method of quantitatively assessing locomotor performance in both living and fossil species by providing a new, potentially more accurate and reliable means of making inferences about locomotor behavior and evolution. As the evolution of the genus Homo is marked by a significant increase in leg length, this model will be especially useful in testing current hypotheses regarding the evolution of hominid locomotor and foraging behavior.Given the diversity of locomotor adaptations evident in living and extinct species, the inability to predict locomotor performance reliably and quantitatively from limb design represents a significant shortcoming in our understanding of locomotor adaptation and ecology. This study will address this issue by testing a relatively simple model that explicitly incorporates leg length as a determinant of locomotor energy cost, and by testing the effect of leg length on maximum and preferred speeds. This project also will promote the integration of graduate training and research in physical anthropology with experimental physiology and biomechanics.