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Introducing Statistical Persistence Decay: A Quantification of Stride-to-Stride Time Interval Dependency in Human Gait
被引:9
作者:
Raffalt, P. C.
[1
,2
]
Yentes, J. M.
[3
]
机构:
[1] Charite Univ Med Berlin, Julius Wolff Inst Biomech & Musculoskeletal Regen, Berlin, Germany
[2] Univ Copenhagen, Dept Biomed Sci, Copenhagen, Denmark
[3] Univ Nebraska, Dept Biomech, Ctr Res Human Movement Variabil, Omaha, NE 68182 USA
基金:
美国国家卫生研究院;
关键词:
Walking;
Dynamics;
Nonlinear behaviour;
Entropy;
DFA;
Stride time fluctuations;
LONG-RANGE CORRELATIONS;
HUMAN WALKING;
MOVEMENT VARIABILITY;
APPROXIMATE ENTROPY;
MULTISCALE ENTROPY;
NONLINEAR DYNAMICS;
FRACTAL DYNAMICS;
SAMPLE ENTROPY;
FLUCTUATIONS;
SERIES;
D O I:
10.1007/s10439-017-1934-1
中图分类号:
R318 [生物医学工程];
学科分类号:
0831 ;
摘要:
Stride-to-stride time intervals during human walking are characterised by predictability and statistical persistence quantified by sample entropy (SaEn) and detrended fluctuation analysis (DFA) which indicates a time dependency in the gait pattern. However, neither analyses quantify time dependency in a physical or physiological interpretable time scale. Recently, entropic half-life (ENTA 1/2) has been introduced as a measure of the time dependency on an interpretable time scale. A novel measure of time dependency, based on DFA, statistical persistence decay (SPD), was introduced. The present study applied SaEn, DFA, ENTA 1/2, and SPD in known theoretical signals (periodic, chaotic, and random) and stride-to-stride time intervals during overground and treadmill walking in healthy subjects. The analyses confirmed known properties of the theoretical signals. There was a significant lower predictability (p = 0.033) and lower statistical persistence (p = 0.012) during treadmill walking compared to overground walking. No significant difference was observed for ENTA 1/2 and SPD between walking condition, and they exhibited a low correlation. ENTA 1/2 showed that predictability in stride time intervals was halved after 11-14 strides and SPD indicated that the statistical persistency was deteriorated to uncorrelated noise after 50 strides. This indicated a substantial time memory, where information from previous strides affected the future strides.
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页码:60 / 70
页数:11
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