Biomechanics, Control, and Energetics of Human Locomotion in the Real World

在现实世界中，人类要面对各种各样的步行表面，包括未铺设的地面、街道路缘和不完美的人行道。然而，关于运动的生物力学、控制力和能量学的许多已知知识仅限于平坦和水平的表面。但在现实世界的地形中，如果没有实验室良好控制的条件，也很难获得定量的生物力学数据。这些差距需要通过结合专门为现实世界设计的新技术来解决，这些新技术将应用于控制良好的实验室研究，以更好地模拟此类环境，并应用于真实世界研究，以更好地量化人类实际上如何适应不同的地面。*这个项目从实验室和现实世界两个方向弥合了鸿沟。在实验室中，我们将进行将传统生物力学技术应用于不平坦地形的研究。这将通过新的方法和实验来实现。例如，我们将使用仪表式跑步机(测量每条腿下的地面反作用力)，以适应不同的表面，如不平坦的地形，不同的幅度或顺应性。结合运动捕捉，这将使地形幅度对整体稳态步态、步态可变性和能量成本的影响得到充分的生物力学表征。我们还将测试生物力学任务需求如何随地形变化，并检查代谢成本增加的机制基础。*我们还将使用改进的生物力学捕捉方法，研究各种真实环境中的运动。大多数可穿戴传感器提供相对简单的测量方法，如步进计时，但无法获得实验室获得的细粒度信息。我们已经开发了新的算法，使用鞋装惯性测量单元来重建每只脚在太空中的轨迹，从中可以获得步长和可变性或脚抬起度等测量数据，其精度可与实验室媲美。这些方法将描述人类如何适应具有挑战性的表面，如松散的砾石或斜坡上的沙子。我们还将把这些生物力学测量与氧气呼吸测量结合起来，以评估代谢成本。对于不平坦的地形，能源成本预测的最新技术是使用回归方程，其中考虑了行走速度、载重和地形难度的粗略和主观指标。随着更好地了解机械和代谢变量如何共同变化，将有可能更客观地表征地形难度，并对能源成本具有更好的可预测性。我们还将探索步态在长距离中的变化，以确定疲劳对平衡和经济的影响。这些研究将提高研究运动的能力，以及对人类在崎岖地形上的适应能力的理解。

Humans contend with a variety of walking surfaces in the real world, including unpaved ground, street curbs, and imperfect sidewalks. However, much of what is known about the biomechanics, control, and energetics of locomotion is confined to flat and level surfaces. But in real-world terrain, it is also difficult to gain quantitative, biomechanical data without the well-controlled conditions of the laboratory. These gaps need to be addressed through a combination of new techniques expressly designed for the real world, to be applied to well-controlled laboratory studies that better model such environments, and to real-world studies that better quantify how humans actually adapt to different ground surfaces. ******This program bridges the gap from both directions: the laboratory and the real world. In the laboratory, we will conduct studies adapting conventional biomechanics techniques to uneven terrain. This will be enabled by new methods and experiments. For example, we will use an instrumented treadmill (measuring ground reaction forces under each leg), adapted to allow for changeable surfaces such as uneven terrain, varying in amplitude or compliance. In conjunction with motion capture, this will enable full biomechanical characterization of the effect of terrain amplitude on overall steady-state gait, gait variability, and energetic cost. We will also test how biomechanical task demands vary with terrain, and examine the mechanistic basis for increased metabolic cost. ******We will also examine locomotion in a variety of real-world environments, using improved biomechanical capture methods. Most wearable sensors provide relatively simple measures such as step timing, but cannot obtain the fine-grained information obtained in the laboratory. We have developed new algorithms to use shoe-mounted inertial measurement units to reconstruct each foot's trajectory in space, from which measures such as stride length and variability, or lifting of the foot, can be obtained with accuracy comparable to laboratory. These methods will characterize how humans adapt their gait to challenging surfaces such as loose gravel or sand on an incline. We will also couple these biomechanical measures with oxygen respirometry to assess metabolic cost. The state of the art in energy cost predictions for uneven terrain is to use regression equations factoring in walking speed, load carriage, and a crude and subjective index of terrain difficulty. With better understanding of how mechanical and metabolic variables co-vary, it will be possible to characterize terrain difficulty more objectively and with better predictability for energy cost. We will also explore how gait changes over long distances, to determine how balance and economy are affected by fatigue. These studies will improve both the capabilities for studying locomotion, as well as understanding of the human adaptations on uneven terrain.