Age-related differences in lower extremity power after support surface perturbations
Age-related differences in lower extremity power after support surface perturbations
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DOI：
10.1046/j.1532-5415.2002.50505.x
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发表时间：
2002-11-01
影响因子：
6.3
通讯作者：
Jensen, JL
中科院分区：
文献类型：
--
作者：
Hall, CD;Jensen, JL
目的：本研究的目的是检查与产生、吸收和转移由扰动引入的机械能的能力相关的综合测量。据推测，这一测量将揭示与年龄相关的差异，导致不同的平衡恢复反应（即足就位和代偿步骤）。设计：横断面、描述性研究。地点：俄勒冈大学运动控制实验室。参与者：18 名年轻（18-35 岁）和 21 名年长（65-85 岁）女性接受了不同幅度和不同幅度的向前和向后支撑表面平移。测量：在使用足就位响应的最大扰动以及发生步骤的后续扰动时检查下肢峰值正关节功率和峰值负肌肉功率。峰值正联合功率描述了能量被动转移到节段中的最大速率，并且指示了该节段的最大不稳定。峰值负肌力是肌肉能量吸收的最大速率，它减少了扰动对节段的影响。结果：反向扰动后，年龄对肌力有显着的主效应，反应类型对关节力有显着的主效应。对于正向条件，反应类型仅对肌力有显着的主效应。结论：支撑面扰动后出现代偿阶跃的机械原因是明确的；足部到位响应比补偿步骤对能量要求更高。能量分析表明，机械基础是老年人依赖代偿步骤的原因之一：老年人肌肉吸收较少的能量。这项研究的结果还强调了近端膝关节和髋关节肌肉组织与远端踝关节肌肉组织的重要性。
OBJECTIVES: The purpose of this study was to examine a comprehensive measure relating to the ability to generate, absorb, and transfer mechanical energy introduced by a perturbation. It was hypothesized that this measure would reveal age-related differences leading to different balance recovery responses (i.e., feet-in-place and compensatory step).DESIGN: Cross-sectional, descriptive study.SETTING: The Motor Control Laboratory at the University of Oregon.PARTICIPANTS: Eighteen younger (aged 18-35) and 21 older (aged 65-85) women received forward and backward support surface translations of varying amplitudes and velocities.MEASUREMENTS: Lower extremity peak positive joint power and peak negative muscle power were examined at the largest perturbation in which a feet-in-place response was used and the subsequent perturbation where a step occurred. Peak positive joint power depicts the maximum rate of passive transfer of energy into a segment and is indicative of the maximum destabilization of that segment. Peak negative muscle power is the maximum rate of energy absorption by muscle, which reduces the effect of the perturbation on the segment.RESULTS: After a backward perturbation, there was a significant main effect of age for muscle power and a significant main effect of response type for joint power. For the forward condition, there was a significant main effect of response type for muscle power only.CONCLUSIONS: The mechanical reason for the emergence of the compensatory step after support-surface perturbations is clear; the feet-in-place response is energetically more demanding than the compensatory step. The energy analysis suggests a mechanical basis as one reason for older adults' reliance on the compensatory step: older adult muscles absorb less energy. The results of this study also highlight the importance of the proximal knee and hip musculature versus the distal ankle musculature.