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Fig. 4. The peak in kinetic energy of the centre of mass,
Ek=Ek,f+Ek,v,
attained because of gravity in its motion forwards and downwards is greater
than the peak attained because of the muscular push in its motion forwards and
upwards. Note that the downward/upward asymmetry decreases with speed due to
the large increase of Ek,f relative to
Ek,v (Fig.
1). The difference between the two peaks attained by
Ek at each step also remains positive at the highest
running speeds (inset). Statistics as in
Fig. 2.