Cho Chiung-Yu, Gilchrist Louise, White Scott
Department of Physical Therapy, Medical College, National Cheng Kung University, Tainan, Taiwan.
Gerontology. 2008;54(2):120-7. doi: 10.1159/000118603. Epub 2008 Feb 26.
The incidence of falls among older adults is high and the risk factors are often complex in nature. Considerable research has been done in the area of age-related changes of balance in an attempt to better understand the increased risk of falls. Studies of cognitive changes, however, suggest that the elderly are less able to divide their attention between two or more activities. This inability to divide attention could explain the increased risks of falls in the elderly.
To investigate the effects of divided attention, age and prior knowledge of movement path, on kinetic measures and the position of the sacral marker relative to the center of pressure (COP) when individuals perform a rapid sidestep during walking.
32 young and 32 old adults participated in this study. Subjects walked and took a sidestep without interrupting forward progression. An arithmetic task was performed during half of the walking trials with the sidestep direction preplanned or unknown. Peak lateral ground reaction force, mean distance between COP and sacrum, walking velocity, performance speed and accuracy of the cognitive task were measured.
Both groups significantly decreased their mediolateral distance between the sacral marker and the COP in the dual-task trials (p = 0.04). Both groups significantly decreased their walking speed in the dual-task trials (p < 0.0001). Prior knowledge of the sidestep direction significantly affected the peak lateral ground reaction force and the sacral marker to COP distance but the differences were age-dependent. Young adults had a larger value in the unknown condition than in the preplanned condition (p < 0.0001). For the cognitive task, both groups decreased their performance speed (p < 0.0001) but maintained their performance accuracy as compared to the baseline data (p > 0.05).
Our results revealed that old adults tended to be conservative, when facing the dual-task trials or unknown test condition. The fact that the older adults in the current study did not perform similarly to the younger adults suggests that they might have a fear of fall when facing a challenging balance task.
老年人跌倒的发生率很高，且危险因素往往复杂多样。为了更好地理解跌倒风险增加的原因，在与年龄相关的平衡变化领域已经开展了大量研究。然而，关于认知变化的研究表明，老年人在两项或多项活动之间分配注意力的能力较弱。这种无法分配注意力的情况可能解释了老年人跌倒风险增加的原因。
研究在个体行走过程中进行快速侧步时，注意力分配、年龄以及对运动路径的先验知识对动力学指标以及骶骨标记相对于压力中心（COP）位置的影响。
32名年轻人和32名老年人参与了本研究。受试者在不中断向前行进的情况下行走并进行侧步。在一半的行走试验中，进行一项算术任务，侧步方向预先设定或未知。测量了峰值侧向地面反作用力、COP与骶骨之间的平均距离、行走速度、认知任务的执行速度和准确性。
在双任务试验中，两组受试者骶骨标记与COP之间的内外侧距离均显著减小（p = 0.04）。在双任务试验中，两组受试者的行走速度均显著降低（p < 0.0001）。侧步方向的先验知识显著影响峰值侧向地面反作用力和骶骨标记到COP的距离，但差异与年龄有关。年轻人在未知条件下的值大于预先设定条件下的值（p < 0.0001）。对于认知任务，与基线数据相比，两组受试者的执行速度均降低（p < 0.0001），但执行准确性保持不变（p > 0.05）。
我们的结果表明，老年人在面对双任务试验或未知测试条件时往往较为保守。本研究中老年人的表现与年轻人不同，这一事实表明他们在面对具有挑战性的平衡任务时可能存在跌倒恐惧。
