Random stride intervals with memory.

The stride interval in normal human gait is not strictly constant, butfluctuates from step to step in a random manner. Herein we show thatcontrary to the traditional assumption of uncorrelated random errors,these fluctuations have long-time memory. However, rather than being amonofractal process as found earlier, there exists a multiplicative timescale that characterizes the process in addition to the fractal dimension.Further, these long-time correlations are interpreted in terms of anallometric control process.