McGorry Raymond W, Chang Chien-Chi, DiDomenico Angela
Liberty Mutual Research Institute for Safety, 71 Frankland Road, Hopkinton, MA 01748, USA.
Appl Ergon. 2008 Nov;39(6):678-84. doi: 10.1016/j.apergo.2007.12.006. Epub 2008 Feb 15.
This paper describes the observation of rearward movement (RM) of the heel following heel strike occurring during normal gait. Thirty-one participants recruited as part of a larger study on slip kinematics walked the length of an 8-m runway at a speed of 1.5 m/s. Several floor surfaces, presented dry and with contaminant, were used for the purpose of eliciting a wide range of small slip distances. The normal force applied to a forceplate mounted in the runway was used to identify heel strike, as well as to calculate the utilized coefficient of friction during early stance phase. A motion analysis system tracked the displacement of two heel-mounted markers, and the data were used to derive kinematic variables related to the heel strike event. Results showed that RMs occurred in 18.1% of 494 trials, with a mean rearward displacement of 5.02 (+/-3.68) mm. When present, RMs occurred in close temporal proximity to heel strike, typically completing RM within 40 ms of the heel strike event. When divided into groups by age, older participants (>40 years) were more than twice as likely to have RMs as younger participants. When grouped by height or weight, differences in the proportion of trials with RMs were small. In trials where RMs were observed, forward slip distances were significantly less than for trials with no RMs, 2.17 (+/-3.87) mm vs. 12.58 (+/-10.71) mm, respectively. The time until the heel stopped moving during the post-heel strike period was not significantly different between RM and non-RM trials. Further investigation of this gait feature may improve understanding of normal gait patterns and may have implications for future slipmeter development.
本文描述了在正常步态中足跟触地后足跟向后移动（RM）的观察情况。作为一项关于滑倒运动学的大型研究的一部分，招募了31名参与者，他们以1.5米/秒的速度在一条8米长的跑道上行走。使用了几种干燥和有污染物的地面，以引发各种小的滑倒距离。作用于安装在跑道上的测力板的法向力用于识别足跟触地，以及计算早期站立阶段的利用摩擦系数。一个运动分析系统跟踪两个安装在足跟的标记的位移，这些数据用于得出与足跟触地事件相关的运动学变量。结果显示，在494次试验中有18.1%出现了RM，平均向后位移为5.02（±3.68）毫米。当出现RM时，其发生时间与足跟触地非常接近，通常在足跟触地事件的40毫秒内完成RM。按年龄分组时，年龄较大的参与者（>40岁）出现RM的可能性是年轻参与者的两倍多。按身高或体重分组时，出现RM的试验比例差异较小。在观察到RM的试验中，向前滑倒距离明显小于没有RM的试验，分别为2.17（±3.87）毫米和12.58（±10.71）毫米。足跟触地后足跟停止移动的时间在有RM和无RM的试验之间没有显著差异。对这种步态特征的进一步研究可能会增进对正常步态模式的理解，并可能对未来防滑计的开发产生影响。
