  We present a nonlinear stochastic model of the human gait control system in a
variety of gait regimes. The stride interval time series in normal human gait
is characterized by slightly multifractal fluctuations. The fractal nature of
the fluctuations become more pronounced under both an increase and decrease in
the average gait. Moreover, the long-range memory in these fluctuations is lost
when the gait is keyed on a metronome. The human locomotion is controlled by a
network of neurons capable of producing a correlated syncopated output. The
central nervous system is coupled to the motocontrol system, and together they
control the locomotion of the gait cycle itself. The metronomic gait is
simulated by a forced nonlinear oscillator with a periodic external force
associated with the conscious act of walking in a particular way.
