Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, William Henry Duncan Building, 6 West Derby Street, Liverpool L7 8TX, UK.
School of Biological and Environmental Sciences, Liverpool John Moores University, James Parsons Building, Bryon Street, Liverpool L3 3AF, UK.
J Exp Biol. 2024 Nov 1;227(21). doi: 10.1242/jeb.246787. Epub 2024 Nov 5.
Our current understanding of human gait is mostly based on studies using hard, level surfaces in a laboratory environment. However, humans navigate a wide range of different substrates every day, which incur varied demands on stability and efficiency. Several studies have shown that when walking on natural compliant substrates there is an increase in energy expenditure. However, these studies report variable changes to other aspects of gait such as muscle activity. Discrepancies between studies exist even within substrate types (e.g. sand), which suggests that relatively 'fine-scale' differences in substrate properties exert quantifiable influences on gait mechanics. In this study, we compared human walking mechanics on a range of sand substrates that vary in overall foot sinking depth. We demonstrated that variation in the overall sinking depth in sand was associated with statistically significant changes in joint angles and spatiotemporal variables in human walking but exerted relatively little influence on pendular energy recovery and muscle activations. Significant correlated changes between gait metrics were frequently recovered, suggesting a degree of coupled or mechanistic interaction in their variation within and across substrates. However, only walking speed (and its associated spatiotemporal variables) correlated frequently with absolute foot sinkage depth within individual sand substrates, but not across them. This suggests that a causative relationship between walking speed and foot sinkage depth within individual sand substates is not coupled with systematic changes in joint kinematics and muscle activity in the same way as is observed across sand substrates.
我们目前对人类步态的理解主要基于在实验室环境中使用坚硬、水平表面进行的研究。然而，人类每天都会在各种不同的基质上行走，这些基质对稳定性和效率有不同的要求。有几项研究表明，当在自然弹性基质上行走时，能量消耗会增加。然而，这些研究报告了步态其他方面的变化，如肌肉活动。即使在同一基质类型（例如沙子）内，研究之间也存在差异，这表明基质特性的相对“精细”差异对步态力学有可量化的影响。在这项研究中，我们比较了人类在一系列不同总沉陷深度的沙地上行走的力学特性。我们证明，沙地上总沉陷深度的变化与人类行走时关节角度和时空变量的统计学显著变化相关，但对摆荡能量回收和肌肉激活的影响相对较小。步态指标之间经常出现相关的变化，这表明它们在不同基质之间的变化存在一定程度的耦合或机械相互作用。然而，只有行走速度（及其相关的时空变量）与个体沙地上的绝对沉降深度经常相关，而不是在沙地上相关。这表明，在个体沙地上，行走速度与沉降深度之间的因果关系与关节运动学和肌肉活动的系统性变化没有耦合，而在沙地上则观察到了这种关系。
