Patla A E, Frank J S, Winter D A, Rietdyk S, Prentice S, Prasad S
Department of Kinesiology, University of Waterloo, Ontario, Canada.
Clin Biomech (Bristol). 1993 Jul;8(4):179-84. doi: 10.1016/0268-0033(93)90012-7.
The balance control system of a group of healthy and fit, young and elderly subjects was studied during the initiation of stepping in one of three directions: forward, sideways, and backwards in response to a light cue. The performance of these movements requires shifting support from two to one foot, moving the centre of mass outside the initial base of support and creating a new support configuration. By recording and analysing the vertical ground reaction force beneath the subject's stepping foot, we were able to examine the two phases prior to limb lift-off for stepping: reaction time and weight transfer time. Both reaction time and weight transfer time increased with age: The elderly subjects had a proportionately larger increase in weight transfer time compared to the reaction time. The peak force generated showed an age by stepping direction effect: the elderly had a significantly lower peak force for the forwards stepping compared to the younger subjects. The larger increase in weight transfer results in a slower stepping response. Since a stepping task is often recruited to avoid a fall, the increase in response execution time can have undesirable consequences.
研究了一组健康且身体状况良好的年轻人和老年人在响应轻提示而朝三个方向之一（向前、向侧方和向后）迈步起始阶段的平衡控制系统。这些动作的执行需要将支撑从双脚转移到单脚，将重心移至初始支撑面之外并形成新的支撑构型。通过记录和分析受试者迈步脚下方的垂直地面反作用力，我们得以检查肢体离地迈步前的两个阶段：反应时间和重量转移时间。反应时间和重量转移时间均随年龄增长而增加：与反应时间相比，老年受试者的重量转移时间增加幅度更大。所产生的峰值力呈现出年龄与迈步方向的效应：与年轻受试者相比，老年人向前迈步时的峰值力显著更低。重量转移的更大增加导致迈步反应更慢。由于迈步任务通常是为避免跌倒而进行的，反应执行时间的增加可能会产生不良后果。
