Department of Movement Science, Sport and Leisure Studies, Westfield State University, Westfield, MA, USA.
Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, USA.
J Biomech. 2020 May 7;104:109710. doi: 10.1016/j.jbiomech.2020.109710. Epub 2020 Feb 28.
Older adults have poorer lateral balance and deficits in precision stepping accuracy, but the way these deficits manifest with lateral step distance is unclear. The purpose of this study was to investigate aging effects on lateral precision stepping performance in reaction to near and distant foot placement targets during treadmill walking. We hypothesized that older adults would step to targets later and less accurately than young adults, and that these difference would be more pronounced for distant targets. During the study, young and older adults stepped on lateral targets projected onto the surface of a treadmill one stride prior to their targeting step. We measured stepping accuracy to the target, the time when the swing foot diverged from its normal swing trajectory, and swing phase gluteus medius activity. Both groups had similar performance stepping to near targets, suggesting that giving older subjects a full stride to react to target location mitigates visuomotor processing delays that have contributed to deficits in stepping performance in prior studies. However, when stepping to distant targets, older adults had larger errors and later divergence times than young adults. This suggests that age-related deficits other than those in visuomotor processing contribute to poorer performance for more difficult stepping tasks. Furthermore, while young adults increased early swing gluteus medius activity with lateral target distance, older adults did not. This is the first study to show a potential neuromuscular basis for precision stepping deficits in older adults.
老年人的横向平衡能力较差，精确踏步步幅准确性较差，但这些缺陷以横向踏步步幅的方式表现出来的方式尚不清楚。本研究旨在探讨在跑步机上行走时，对近距和远距脚部放置目标的反应中，老年人横向精确踏步步幅表现的老化效应。我们假设老年人的踏步步幅会比年轻人更晚、更不准确，并且对于远距目标，这种差异会更加明显。在研究过程中，年轻人和老年人在目标步之前一步踏在投射到跑步机表面的横向目标上。我们测量了踏向目标的准确性、摆动脚偏离正常摆动轨迹的时间以及摆动相臀中肌的活动。两组在接近目标的踏步步幅表现相似，这表明给老年人一个完整的步幅来反应目标位置，可以减轻先前研究中导致踏步步幅表现缺陷的视觉运动处理延迟。然而，当踏向远距目标时，老年人的错误和摆动脚偏离时间都比年轻人更大。这表明与年龄相关的除了视觉运动处理之外的其他缺陷，会导致更困难的踏步步幅任务表现更差。此外，虽然年轻人随着横向目标距离的增加而增加早期摆动臀中肌的活动，但老年人没有。这是第一项表明老年人精确踏步步幅缺陷存在潜在神经肌肉基础的研究。
