SIFiguresPt2.zip from Consistent inconsistencies in braking: a spatial analysis

The dynamic system that is the bipedal body in motion is of interest to engineers, clinicians and biological anthropologists alike. Spatial statistics is more familiar to public health researchers as a way of analysing disease clustering and spread, nonetheless, this is a practical approach to the two-dimensional topography of the foot. We quantified the clustering of the centre of pressure (CoPs) on the foot for peak braking and propulsive vertical ground reaction forces (GRF) over multiple, contiguous steps to assess the consistency of the location of peak forces on the foot during walking. The vertical GRFs of eleven participants were collected continuously via a wireless insole system (MoticonReGo AG) across various experimental conditions. We hypothesized that CoPs would cluster in the hindfoot for braking and forefoot for propulsion and that braking would demonstrate more consistent clustering than propulsion. Contrary to our hypotheses, we found that CoPs during braking are inconsistent in their location and CoPs during propulsion are more consistent and clustered across all participants and all trials. These results add to our understanding of the applied forces on the foot so that we can better predict fatigue failures and better understand the mechanisms that shaped the modern bipedal form.

运动中的双足躯体这一动态系统，同时受到工程师、临床医师与生物人类学家的共同关注。空间统计学（spatial statistics）作为分析疾病聚集与传播的经典方法，更为公共卫生研究者所熟知；不过将其用于足部二维地形的分析，同样是一种实用的研究路径。我们针对受试者在多个连续行走步幅中的情况，量化了峰值制动与推进阶段的足部压力中心（centre of pressure, CoPs）聚集特征，以此评估行走时足部峰值力位置的一致性。本研究通过无线鞋垫系统（wireless insole system, MoticonReGO AG），在多种实验条件下持续采集了11名受试者的垂直地面反作用力（vertical ground reaction forces, GRF）数据。我们曾提出研究假设：制动阶段的压力中心会聚集于足跟区域，推进阶段则聚集于前足区域，且制动阶段的压力中心聚集一致性会优于推进阶段。然而研究结果与假设相悖：制动阶段的压力中心位置并不一致，而推进阶段的压力中心则在全部受试者与所有试验中均表现出更强的聚集性与位置一致性。本研究结果深化了我们对足部所受外作用力的认知，有助于更精准地预测足部疲劳失效，并进一步理解塑造现代人类双足躯体形态的生物学机制。