基于非线性时间序列法研究人体步行稳定性

Nonlinear time series analysis of gait stability during walking

目的应用非线性时间序列分析方法,研究健康老年与青年志愿者的步行稳定性,为更全面评估人体的动态平衡、预测跌倒风险提供重要依据。方法应用VICON运动捕捉系统,采集肌骨系统健康志愿者(7名老年和10名青年)在不同步速(80%、100%1、20%自然步速)下的运动学数据,提取志愿者在30个连续步态周期中,第7颈椎和第10胸椎在前后和左右方向上的位移,以及下肢各关节屈曲伸展和外展内收运动角度,计算位移和运动角度变化的最大Lyapunov指数,比较分析老年与青年组之间步行稳定性差异,以及步速对人体步行稳定性影响。结果青年组步行稳定性优于老年组,并在某些运动节段呈现显著性差异(P<0.01);老年和青年的步行稳定性随步速增加而降低(P<0.05)。结论应用非线性时间序列分析方法中的最大Lyapunov指数,能有效并定量地评测人体步行中各运动节段的稳定性。

Objective To investigate the gait stability of healthy old and young adult volunteers during walking using the nonlinear time series analysis method so as to comprehensively assess the dynamic balance of human and provide important references for the prediction of fall risk.Methods The Vicon motion capture system was used to collect three-dimensional kinematic data of healthy volunteers（seven old subjects and ten young subjects） at different walking speed（80%,100%,120% of the natural walking speed）.The anterior-posterior and medio-lateral motions of the seventh cervical and tenth thoracic vertebrae,as well as the flexion-extension and abduction-adduction angles of the lower extremity joints,were obtained from 30 consecutive gait cycles to calculate the largest Lyapunov exponents and analyze the difference of gait stability between the old and young group and the influence of walking speed on gait stability.Results The gait stability in the young group was better than that in the old group,and there were significant differences in certain motion segments（P0.01）.The gait stability in both groups were reduced with the increase of speed（P0.05）.Conclusions The largest Lyapunov exponent based on nonlinear time series analysis method can be used to effectively and quantitatively analyze the gait stability of each motion segment in human during walking.