Henriksson Marketta, Hirschfeld Helga
Neurotec Department 23100, Motor Control and Physical Therapy Research Laboratory, Karolinska Institutet, SE-141 83 Stockholm, Sweden.
Gait Posture. 2005 Apr;21(3):289-96. doi: 10.1016/j.gaitpost.2004.03.001.
An understanding of age-related changes in motor behaviour is important when considering the design of training programs for fall-prevention in the elderly. Gait initiation is a phase of walking during which falls are often provoked and this study compares strategies employed by healthy older and young adults during gait initiation. Twenty-nine older, physically active subjects (65-79 years) and 28 younger individuals (23-40 years) were instructed to cross a staged road, when a traffic light changed from red to green, leading with a freely chosen or predetermined leg. Electromyography of tibialis anterior (TA) and lateral gastrocnemius (LG) muscles, ground reaction forces exerted and step lengths were recorded. The elderly displayed several striking differences compared to the young individuals. Weight bearing during initial standing was considerably more unequal and reaction time was 46% longer, with identical duration of gait initiation. Swing leg peak posterior force (% BW) tended to be smaller, but the increase of vertical force was larger. Eight elderly and one young subject lacked anticipatory TA onset; however TA anticipation increased with trial number in the elderly group. When the starting leg was predetermined, the deficiency in TA anticipation was no longer apparent. In the stance leg all forces were smaller and LG was recruited later, and unlike the young subjects generally after the swing leg had left the ground. The results revealed that ageing leads to significant alterations in weight bearing and ankle muscle activation in relation to gait initiation. Gait initiation changed significantly when the starting leg was predetermined and, in the elderly, with repetition.
在考虑为老年人设计预防跌倒的训练计划时，了解与年龄相关的运动行为变化非常重要。步态起始是步行过程中的一个阶段，在此期间经常会引发跌倒，本研究比较了健康老年人和年轻人在步态起始过程中采用的策略。29名年龄在65 - 79岁之间、身体活跃的老年受试者和28名年龄在23 - 40岁之间的年轻个体被要求在交通信号灯从红灯变为绿灯时穿过一条模拟道路，用自由选择或预先确定的腿先行。记录了胫前肌（TA）和外侧腓肠肌（LG）的肌电图、施加的地面反作用力和步长。与年轻人相比，老年人表现出几个显著差异。初始站立时的负重明显更不均衡，反应时间长46%，而步态起始持续时间相同。摆动腿的峰值向后力（%体重）往往较小，但垂直力的增加较大。8名老年受试者和1名年轻受试者缺乏TA预期起始；然而，老年组中TA预期随试验次数增加。当起始腿预先确定时，TA预期的不足不再明显。在支撑腿中所有力量都较小，LG募集较晚，与年轻受试者不同的是通常在摆动腿离开地面后。结果表明衰老导致与步态起始相关的负重和踝关节肌肉激活发生显著改变。当起始腿预先确定时以及在老年人中随着重复，步态起始发生了显著变化。
