Santhiranayagam Braveena K, Sparrow W A, Lai Daniel T H, Begg Rezaul K
Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria 8001, Australia; College of Sport & Exercise Science, Victoria University, Melbourne, Victoria 8001, Australia.
Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria 8001, Australia; College of Engineering & Science, Victoria University, Melbourne, Victoria 8001, Australia.
Gait Posture. 2017 Mar;53:73-79. doi: 10.1016/j.gaitpost.2016.11.044. Epub 2016 Nov 29.
Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTC) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an 'indicative' toe height at the individual's average swing phase time (MTC) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTC. This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact.
行走表面上方的最小脚趾间隙（MTC）是脚趾轨迹控制的关键指标，因为它与绊倒风险相关。并非所有步态周期在摆动阶段都有明确界定的MTC，但以前很少有关于非MTC步态周期生物力学特征的描述。本报告研究了15名老年人（平均73.1岁）和15名年轻对照者（平均26.1岁）的个体内非MTC步态周期特征。参与者在电动跑步机上执行以下任务：偏好速度行走、双重任务行走（端着一杯水）和双重任务速度匹配对照。使用三维运动捕捉系统获取脚趾位置-时间坐标。当存在MTC时，提取MTC处的脚趾高度（MTC）。计算各年龄组和个体的非MTC步态周期比例。对于非MTC步态周期，在多个非MTC步态周期中对观察到的MTC周期在个体平均摆动阶段时间（MTC）处的“指示性”脚趾高度进行平均。在偏好速度行走中，年轻人的非MTC步态周期为2.9%，老年人为18.7%。在受限行走条件下，两组的非MTC步态周期均增加，一些老年人超过90%，证实非MTC步态周期是下肢轨迹控制中与衰老相关的现象。对于所有参与者，非MTC步态周期的指示性脚趾高度中位数大于MTC中位数。这一结果表明，通过采用更多间隙更高的非MTC步态周期来消除生物力学上有危险的MTC事件，有助于降低脚趾与地面接触的可能性。
