Sundermier L, Woollacott M H, Jensen J L, Moore S
Department of Exercise and Movement Science, College of Arts and Sciences, University of Oregon, Eugene 97403-1240, USA.
J Gerontol A Biol Sci Med Sci. 1996 Mar;51(2):M45-52. doi: 10.1093/gerona/51a.2.m45.
This study tested balance behavior of young adults and aging adults with and without balance problems in response to visual flow from a moving visual surround.
Balance behavior was indexed by force plate measures of maximum anterior/posterior displacement of the center of foot pressure and horizontal shear forces. The sample included normal young adults (n = 13; mean age 23 years, +/- 7.5), normal aging adults (n = 13; mean age 76 years, +/- 6.5), and aging adults with balance problems not directly attributable to a diagnosable neurological disease or dysfunction (n = 13; mean age 79 years, +/- 5.8).
The balance-affected aging group had statistically greater sway responses than the young group when the stimulus was unexpected (as in the first trial; p < .05). Some individuals in each group had large responses that were statistical outliers from the group median. The balance-affected group had significantly greater shear forces than the young group.
Greater sway responses suggest over-reliance on visual cues for posture control in the balance-affected aging group, which may be related to underlying, borderline somatosensory deficits, as indicated by the patterns of subclinical indications for somatosensory impairments on neurological exams in this group. Visually sensitive postural control, however, may issue from several different underlying processes. Elevated shear forces during balance responses in the balance-affected group suggest a greater use of hip movements in addition to ankle movements for postural adjustments.
本研究测试了有和没有平衡问题的年轻人和老年人在面对移动视觉环境中的视觉流时的平衡行为。
平衡行为通过测力板测量足压中心的最大前后位移和水平剪切力来衡量。样本包括正常年轻人（n = 13；平均年龄23岁，±7.5）、正常老年人（n = 13；平均年龄76岁，±6.5）以及有平衡问题但并非直接归因于可诊断神经疾病或功能障碍的老年人（n = 13；平均年龄79岁，±5.8）。
当刺激出乎意料时（如在第一次试验中），受平衡影响的老年组的摇摆反应在统计学上比年轻组更大（p <.05）。每组中都有一些个体的反应较大，是组中位数的统计异常值。受平衡影响的组的剪切力明显大于年轻组。
更大的摇摆反应表明受平衡影响的老年组在姿势控制上过度依赖视觉线索，这可能与潜在的、临界的体感缺陷有关，如该组神经学检查中体感损伤的亚临床指征模式所示。然而，视觉敏感的姿势控制可能源于几种不同的潜在过程。受平衡影响的组在平衡反应期间升高的剪切力表明，除了踝关节运动外，还更多地利用髋关节运动进行姿势调整。
