Heasley Karen, Buckley John G, Scally Andy, Twigg Pete, Elliott David B
Vision and Mobility Laboratory, Department of Optometry, University of Bradford, West Yorkshire, UK.
Invest Ophthalmol Vis Sci. 2005 Oct;46(10):3584-8. doi: 10.1167/iovs.05-0059.
The risk of falling increases dramatically with age, and visual impairment is known to be an important risk factor. Therefore, it is highly pertinent to assess the effects of age and vision on the performance of everyday tasks linked to falling, such as stepping from one level to another.
Nine young (age, 26 +/- 4 years) and ten elderly (age, 72 +/- 5 years) subjects performed a stepping-up task of three different heights. Their stepping strategies with blurred and optimally corrected vision were compared. Center of mass (CM), center of pressure (CP) dynamics (in the mediolateral and anteroposterior directions), and foot clearance parameters were determined, and statistical regression modeling was applied.
Elderly subjects spent 20% more time (P = 0.03) than young subjects during double support and they had reduced anteroposterior CM-CP divergence (P < 0.001) during double support and slower anteroposterior (P < 0.001) and mediolateral (P = 0.002) CM velocities during initiation of movement and single limb support. Blur caused similar adaptations, such as increased toe clearance, across both age groups, though mediolateral (ML) CM-CP divergence in elderly subjects was significantly more reduced than in young subjects (P < 0.001).
Findings indicate, in general, that older subjects used a more cautious and controlled stepping strategy. However, the lack of significant age differences in toe clearance suggests this strategy was mainly aimed at reducing ML instability rather than increasing margins of safety regarding toe clearance.
跌倒风险会随着年龄的增长而急剧增加，而视力障碍是一个重要的风险因素。因此，评估年龄和视力对与跌倒相关的日常任务（如从一个高度跨到另一个高度）表现的影响具有高度相关性。
9名年轻受试者（年龄26±4岁）和10名老年受试者（年龄72±5岁）完成了三种不同高度台阶的上台阶任务。比较了他们在视力模糊和最佳矫正视力状态下的上台阶策略。测定了重心（CM）、压力中心（CP）动力学（内外侧和前后方向）以及足部离地间隙参数，并应用了统计回归模型。
老年受试者在双支撑阶段比年轻受试者多花费20%的时间（P = 0.03），并且在双支撑阶段前后向CM - CP发散减小（P < 0.001），在运动起始和单腿支撑阶段前后向（P < 0.001）和内外侧（P = 0.002）CM速度较慢。视力模糊在两个年龄组中都引起了类似的适应性变化，如增加了脚趾离地间隙，不过老年受试者的内外侧（ML）CM - CP发散比年轻受试者显著减小更多（P < 0.001）。
研究结果总体表明，老年受试者采用了更谨慎和可控的上台阶策略。然而，在脚趾离地间隙方面缺乏显著的年龄差异表明，这种策略主要旨在减少ML方向的不稳定性，而不是增加脚趾离地间隙的安全余量。
