Multifractality in time series of human gait

Abstract

We used the method proposed by Chhabra and Jensen to calculate the multifractal spectra of a database with 50 gait time series of children, ten long-term recording of gait dynamics from healthy young persons and another databases with gait time series of healthy adults and persons with Parkinson, Huntington and amyotrophic lateral sclerosis (ALS) diseases. From the multifractal spectra we obtained the spectra width and we found that the spectra of the healthy young persons are almost monofractal. The spectra of little children are wider and they narrow as the children age increases. The spectra of ill persons are wider than the spectra of healthy persons. In opposition to the interbeat time series where the pathology implies loss of multifractality, in the gait time series the multifractal behavior emerges with the pathology. Gait time series of healthy persons are less complex than gait time series of ill persons. Little children gait time series are more complex than the series of young healthy persons; the width of the mutifractal spectra of children diminishes as their age increases.