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[RC] 50% duty cycle (was: engineers & trot, etc.) - k s swigart

Jim Pascucci said:

I was going to suggest that, from a
"power point" that the having the foot
on the ground longer would be more
efficient, but in both cases you present
one can assume a 50% duty cycle--which
is the most efficient for the body--and that
cleans the slate. (I assume that each horse
will have the foot in the air as long as it has
it on the ground. That's the 50% duty cycle.)

I am curious.  What makes you assume this?  I don't know that it is not
true, but I don't know that it is true either and wonder why you take
this as an assumption as I suspect that it is not.

For instance, when my horse "trots" (I use the word in qoutes because,
to a certain extent it is not a true trot, in that she dissociates the
diagonal pairs slightly), she puts down her hind foot first (i.e. before
the opposing fore) and she picks up her hind foot last (i.e. AFTER the
opposing fore)--I have photos to prove this.

Consequently, during the course of a single stride the hind foot is on
the ground for longer than the opposing front foot. Therefore, since
both the hind leg and the front leg spend the same amount of time during
the entire length of a stride (this is axiomatic), there is no way,
since they aren't spending the same amount of time on the ground, that
they are both spending 50% of the time on the ground and 50% of the time
in the air; one of them is spending more time than the other, so one of
them has to be spending a greater percentage of time than the other.

Additionally (although I do not have a reference for this), I believe
that a high speed film analysis was done of TB racing gallops and they
found that the really fast horses spent most of their time with their
feet in the air (which was a surprise to the researhers), that the
horses were, quite literally, flying.

Because of this study (I will see if I can track the actual thing down),
this suggests that from a "power point" having the foot on the ground is
NOT the most efficient.  Which makes a little bit of sense, the horse is
doing the most work when the foot is on the ground (i.e. weight bearing
and/or pushing off), so, it would seem to me, that what is most
efficient is for horses to spend as little time and effort with their
feet on the ground and most of the time with their feet in the air.

However, I am not sure of any of this (except for what I have pictures
of in my horses).  Is there some reason, either theoretically or
experimentally, to assume that each foot spends exactly 50% of the time
on the ground and 50% of the time in the air?  Have I missed something
in the analysis above of my own horses?

Orange County, Calif.


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