=.2in

Note that unlike variability measures, temporal structure measures
are sensitive to the order of the data points in the time series.
| Table 2: Stride Time Variability | ||||
| 3 & 4 Year Olds | 6 & 7 Year Olds | 11--14 Year Olds | ||
| SD (msec) | Original Time Series | 55 | 31 | 23 |
| After Detrending | 48 | 28 | 22 | |
| 1st 30 Strides | 47 | 25 | 17 | |
| CV (%) | Original Time Series | 6.1 | 3.3 | 2.1 |
| Lowest 30 stride segment | 3.1 | 1.8 | 1.2 | |
| 1st 30 Strides | 5.1 | 2.6 | 1.6 | |
SD: standard deviation; CV: coefficient of variation.
and
denote p < .005 and p < .0001, respectively,
compared to the 6 and 7 year olds.
denotes p < .0001
comparing the oldest and youngest groups.
Kruskal-Wallis tests detected
significant differences among the three groups for all measures (p <
.0001).
| Table 3: Spectral Analysis | |||
| 3 & 4 Year Olds | 6 & 7 Year Olds | 11--14 Year Olds | |
| % High Frequency Power (0.25--0.5 stride | 0.054 | 0.064 | 0.100 |
| Low/High Ratio | 6.8 | 4.1 | 2.3 |
| Low/High Ratio after Detrending | 0.30 | 0.20 | 0.15 |
| % High Frequency Power (0.3--0.4 stride | 0.022 | 0.023 | 0.038 |
| Low/High Ratio | 6.8 | 4.5 | 2.3 |
| Low/High Ratio after Detrending | 0.41 | 0.29 | 0.18 |
denotes p < .05
compared to the 6 and 7 year olds.
denotes p < .005
comparing the oldest and youngest groups.
Kruskal-Wallis tests detected
significant differences among the three groups for all measures except high frequency power.
|
Table 4: Effects of Age on Stride Time Dynamics | |||
| 3 & 4 Year Olds | 6 & 7 Year Olds | 11--14 Year Olds | |
| Variability | | | -- |
| Low/High Frequency Power | | | -- |
| Autocorrelation Decay Time | | -- | -- |
| Fractal Scaling Exponent | | | -- |
Compared to the oldest children in whom stride time dynamics
are the most adult-like.
Note how different aspects of
the temporal structure of the stride dynamics tend to mature at
different ages. (The low/high ratio was not statistically different in the two youngest groups,
however, this representation reflects the observed trend toward a decreased ratio
in the 6 and 7 years olds compared to the 3 and 4 year olds.)





