Stepping up to a new level: Effects of blurring vision in the elderly
Stepping up to a new level: Effects of blurring vision in the elderly
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DOI：
10.1167/iovs.03-1199
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发表时间：
2004-07-01
影响因子：
4.4
通讯作者：
Elliott, DB
中科院分区：
文献类型：
--
作者：
Heasley, K;Buckley, JG;Elliott, DB
目的.研究老年人在完成一个新的水平的单步时，视力模糊对全身质心（CM）动力学和足部间隙参数的影响。12名健康受试者（平均年龄，72.3 ± 4.17岁）完成了一个新的台阶（高度为73和146 mm）。进行了视力最佳矫正和视力扩散模糊的光散射镜片（白内障模拟）。CM和足部间隙参数数据通过分析由五个摄像头、三维（3-D）运动分析系统收集的数据进行评估。当视力模糊时，受试者执行踏步任务所需时间延长11%（P < 0.05），地面反作用力矢量作用点的内外侧位移（即，与地面接触面积上所有压力的加权平均值;所谓的压力中心（CP）从占站立宽度的37.6%下降到28.3% CM与CP之间的最大距离缩短了9.8mm（P < 0.01）足趾间隙（鞋尖与台阶边缘的距离）在水平方向（28%）和垂直方向（19%）均增加（P < 0.05）。这些研究结果表明，当视力模糊时，受试者使用双重安全驱动的适应：首先，为了增加动态稳定性，他们确保CM的水平位置保持靠近支撑底座的中心，其次，他们增加了水平和垂直脚趾间隙，同时向前摆动他们的铅腿以减少绊倒的风险。
PURPOSE. To determine the effects of blurring vision on whole-body center-of-mass (CM) dynamics and foot-clearance parameters in elderly individuals performing a single step up to a new level.METHODS. Twelve healthy subjects (mean age, 72.3 +/- 4.17 years) performed a single step up to a new level ( heights of 73 and 146 mm). Trials were undertaken with vision optimally corrected and with vision diffusively blurred by light-scattering lenses ( cataract simulation). CM and foot-clearance parameter data were assessed by analyzing data collected by a five-camera, three-dimensional (3-D) motion analysis system.RESULTS. When vision was blurred, subjects took 11% longer to execute the stepping task (P < 0.05), mediolateral displacement of the point of application of the ground reaction force vector (i.e., weighted average of all pressures over the area in contact with the ground; the so called center of pressure, CP) decreased from 37.6% of stance width to 28.3% (P < 0.01), maximum distance between the mediolateral position of the CM and CP decreased by 9.8 mm (P < 0.01), and toe clearance ( distance between tip of shoe and edge of step) increased in both the horizontal (28%) and vertical (19%) direction (P < 0.05).CONCLUSIONS. These findings suggest that when vision was blurred, subjects used a twofold safety-driven adaptation: First, to increase dynamic stability they ensured that the horizontal position of their CM was kept close to the center of the base of support and second, they increased horizontal and vertical toe clearance while swinging their lead limb forward to reduce the risk of tripping.