Figure 1.
Left panel: Representative example of the average diffusion plots in bilogarithmic coordinates, obtained by performing DFA on inter-stride interval series (condition CV 1%).
The average plots are computed by point-by-point averaging over the twelve participants performing under the same experimental condition. Right panel: Corresponding plot obtained with the 11-point averaging method. Solid line corresponds to the slope for the 11 points (α), the dashed lines correspond to the slope of the short-term (αshort-term) and long-term (αlong-term) regions of the diffusion plot.
Figure 2.
Mean α exponent (DFA) of inter-beat intervals (white triangles) and inter-stride intervals (squares) in Experiment 1.
(*: p<0.05; N.S.: non-significant differences; error bars: standard deviation). Left panel: The evolution of α for all participants taken together (n = 12) could be interpreted as a progressive increase with increasing CV. Right panel: Qualitatively different changes in α exhibited by two subgroups: group 1 (black squares, n = 8) shows an abrupt switch from anti-persistent to persistent long-range correlations at CV = 0.5%, while group 2 (white squares, n = 4) switches at CV = 1%.
Table 1.
Mean fractal exponents (αDFA) and standard deviation (italics) of inter-beat intervals and inter-stride intervals estimated from all conditions in Experiment 1.
Figure 3.
Correlation between α exponents (DFA) of inter-beat intervals and inter-stride intervals obtained in the four conditions with fractal metronome in Experiment 1.
Upper panel: short-term region of diffusion plots. Lower panel: long-term region of diffusion plots. Significance threshold (*) for correlation coefficients is set at p<0.05 (r10 = 0.58). For the CV = 0.5% condition, subpanels separately show the correlations for the two subgroups of participants (n = 4, upper subpanel, and n = 8, lower subpanel).
Table 2.
Mean fractal exponents (αDFA) and standard deviation (italics) of inter-beat intervals and inter-stride intervals estimated from all conditions in Experiment 2.
Figure 4.
Correlation between α exponents (DFA) of inter-beat intervals and inter-stride intervals obtained in the four conditions with non-isochronous metronome in Experiment 2.
Upper panel: short-term region of diffusion plots. Lower panel: long-term region of diffusion plots. Significance threshold (*) for correlation coefficients is set at p<0.05 (r10 = 0.58).
Figure 5.
Mean coefficients of windowed (15-point window) cross-correlation functions (from lag −10 to lag 10) between inter-beat intervals series and inter-stride intervals series, for the four fractal-metronome pacing conditions in Experiment 1.
The black dashed line shows the significance threshold (r13 = 0.5139, p<.05).