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不清楚。该项目将研究人类和家养狗在行走和跑步过程中腿长对能量消耗和速度的影响，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。在跑步机试验中，将测量两种动物在一定范围内的步行和跑步速度下的能量消耗。一组户外试验也将进行，以测试腿长对最大跑步速度和加速度的影响，并调查能量效率和最大速度和加速度之间的权衡。结果将用于测试模型的预测，特别是增加腿长可以提高步行和跑步时的能量效率和速度，但代价是加速度降低和摆动腿所需的能量增加。包括两足动物（人类）和四足动物（狗）将进一步提供一种方法来研究腿长和运动性能之间的联系，跨越一系列解剖设计。如果成功，该模型将提供一种新的、可能更准确、更可靠的方法来推断运动行为和进化，从而定量评估活体和化石物种的运动表现。由于人属的进化以腿长的显著增加为标志，该模型将在测试有关原始人运动和觅食行为进化的当前假设方面特别有用。鉴于现存和灭绝物种的运动适应多样性，无法从肢体设计中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。本研究将通过测试一个相对简单的模型来解决这个问题，该模型明确地将腿长作为运动能量消耗的决定因素，并通过测试腿长对最大速度和首选速度的影响。此计画也将促进体质人类学研究生训练与研究与实验生理学与生物力学的整合。

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.