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Re: An alternative to ST and AAT
Phillip Bigelow (bh162@scn.org)
Fri, 22 Nov 1996 18:33:44 -0800
Gerrit Hanenburg wrote:
> Striding bipedalism refers to the kind of locomotion in which the body
> is supported by first one leg and then the other,and as the body
> passes over the supporting leg,the other leg swings forward in
> preparation for the next support fase. During transfer of the body
> from the trailing to the leading leg there is a brief period when both
> feet are on the ground.
This is a little off the subject, but:
Moving over to quadrupedal striding: Trotting would certainly be
considered quad-striding, but what about galloping? (Considering that
when a horse gallops, there is a point in the cycle where all four
hooves are in mid-air).
In horse racing, galloping is often refered to as "striding", even
though the actual biomechanics of the motion more roughly approximate
saltative quadrupedalism than anything else! This type of locomotion is
taken to an extreme in the Thompson's Gazelle of Africa (where there
is almost as much of a vertical component to the gallop as there is
a translational component!).
The fastest animal on earth, the cheetah, (70 mph in straight-line
spint-mode) also has all 4 legs in the air much of this time.
The next fastest animal (the bipedal ostrich) is a classic strider,
but in sprint mode it alters it's style a bit (as in the
analogous example, below).
If one watches Olympic sprinters like Michael Johnson in
slow-motion replay, one notes that slightly less than 50%
of the time, both of Johnson's feet are in mid-air. But the fact
that his feet are always alternating in motion makes his sprint-
mode a "stride". Curious, though, that sports-biomechanicists
try to train their sprinters to REDUCE the amount of time that
both feet are in the air. Apparently, *too* much time where both
feet are in mid-air is not efficient. Dimminishing returns, I would
assume.
Just some random thoughts.
<pb>
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