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Fig. 4. Step duration and displacements of the centre of mass in vertical and
forward direction as a function of running speed. (A–C) 1
g, (D–F) 1.3 g. Diamonds (black)
indicate, from top to bottom, the step period (
), the vertical
displacement of the centre of gravity of the body during the step
(Sv) and the step length (L) as a function of the
running speed (
f).
Triangles (blue) indicate the duration (tae) of the
effective aerial phase, and the displacement of the centre of gravity during
this phase in the vertical direction (Sae) and in the
forward direction (Lae). Similarly, squares (red) indicate
the duration (tce) of the effective contact phase and the
corresponding displacements in the vertical direction
(Sce) and in the forward direction
(Lce). The red broken line in each panel indicates the
actual contact time (tc), and the vertical
(Sc) and forward (Lc) displacement of
the centre of mass during it. The blue broken line in each panel indicates the
actual aerial time (ta), and the vertical
(Sa) and forward (La) displacement of
the centre of mass during it. The vertical bars indicate the standard
deviation of the mean calculated in each velocity class; the figures near the
symbols in the upper panels indicate the number of items in the mean. Note
that the step divisions based on the effective contact time and aerial time
correspond to about half of total duration and displacements of the step,
whereas the fraction of the step occupied by the actual contact and aerial
phases varies widely with speed. Note also that the speed beyond which
tae=tce,
Sae=Sce and
Lae=Lce is greater at 1.3
g than at 1 g.
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