老年人身体平衡能力与坐起-行走地反力的样本熵特性的实证研究

Empirical Study of Sample Entropy Characteristics of Sit-to-Walk Motion and Physical Functions of Elderly Humans

坐起-站立是平时生活中最常出现的动作之一。对于下肢功能不断衰弱的老年人而言,坐起-站立过程中常会发生跌倒。文章主要研究的是老年人坐起-站立过程中足底压力的动态特征与身体平衡能力的关系。本次实验在马连洼社区(北京老年人口比例最高的社区之一)进行,项目组共搜集到128例数据,其中男性51人,女性77人,年龄都不小于65岁。利用平衡能力测试对老年人群进行评分,分为正常组、低风险组、中等风险组、高风险组4组。实验时,要求所有的实验对象以最舒适的状态完成坐起-行走动作。左右足的足底压力和力矩数据被记录,并且被样本熵量化。研究结果表明,左右足的足底压力和力矩变量的样本熵的统计特性具有差异,并且在不同老年人群的足底压力和力矩之间也存在差异,尤其以下变量的样本熵在不同组别间存在显著性差异:行走过程中左足在内外侧方向的足底压力(LF_x,P=0.049)、在前后方向的足底压力(LF_y,P=0.025)、在垂直方向上的足底压力(LF_z,P=0.036),行走过程中右足在前后方向上的足底压力(RF_y,P=0.043)、在垂直方向上的足底压力(RF_z,P=0.006)、在内外侧方向上的力矩(RM_x,P=0.041)。以上结果表明,在采集和分析老年人的足底压力数据时应该分开处理。

Sit-to-walk（STW） motion is one of the most common action in daily life. Falls frequently occur, when there is impaired ability to perform STW movements. In this study, the relationships between dynamical characteristics of STW motion and physical functions of elderly people were investigated. The experiments were conducted in Malianwa community, one of the highest proportion of the elderly population of Beijing. 128 elderly（51 males and 77 females, above 65 years） participated in this experiment. Participants were classifi ed into four groups（normal, mild, moderate and severe group） based on physical function test and were instructed to perform STW motion at comfortable state. The data of ground reaction force（GRF） and moment（GRM） between left and right foot was recorded, and quantifi ed by sample entropy. The results showed that there were statistical differences among sample entropies of GRF or GRM between left and right foot. In addition, a subset of variables was significant difference among four groups. Statistical difference was found for the following variables： sample entropies of medial-lateral, anterior-posterior, and superior-inferior GRF of left foot during walking（LFx, P=0.049; LFy, P=0.025; LFz, P=0.036, respectively）; sample entropies of anterior-posterior, and superior-inferior GRF of right foot during walking（RFy, P=0.043; RFz, P=0.006, respectively）; sample entropies of medial-lateral GRM of right foot during walking（RMx, P=0.041）. Therefore, the data of GRF and GRM between left and right foot should be acquired and analyzed separately.