Ridecamp: Re: [RC] Mad Science

> Come back east and look at it.

Ten months and counting, fella.

> What I see is people are showing up with
> bigger and bigger horses and going faster and faster on the same
> courses.

Could be.  It would be interesting to see what the long-term performance and
incidence of lameness is with the bigger horses, especially those carrying
bigger riders (and thus more total mass).  All I can tell you is that in
looking at 1000 Tevis horses, as total mass increased, so did the incidence
of lameness, in an almost linear fashion (with one very notable exception).
There was not any relationship between lameness and how the 'total mass' was
comprised---that is, a 1100 lb horse carrying a 125 lb rider (1225 lb total
mass) was just as likely to go lame as a 1000 lb horse carrying a 225 lb
rider (also 1225 lbs total mass).  What seemed to matter was the total mass
itself, not how the mass was divided up.


>  There is also the issue of efficiency. Is a 1000 pound horse
> carrying 200 pounds more efficient than an 800 pound horse carriying 200
> pounds.

It depends on what your definition of efficient is.  If you're talking about
total Mcals required to move the "package" fifty miles down the road, then
actually, the second horse with a total mass of 1000 lbs will require fewer
calories than the first horse having to move 1200 lbs.  It was all very well
demonstrated in the 80's with oxygen consumption trials at Cornell, as long
as the velocity stays within certain boundaries (similar to endurance
speeds).

Biomechanically, the second horse may or may not be more efficient.  Because
the total mass is less with the second horse, the data from Tevis suggests
that horse is less likely to go lame.  However, because more of the total
mass is being carried over the spine, any deficits in the support system
(small feet, a poorly fitting saddle, bad riding) is going to become much
more critical and likely to cause injury and lameness.  So the second rider
has more *potential* to be the more inefficient system.  But you can't
absolutely predict it either way.

If your definition of efficiency is based solely on who will win a sprint to
the finish (and most people seem to ascribe to this definition, without
considering the other factors), then the first rider wins hands down (all
other things being equal).   The larger horse has presumably more muscle
mass and therefore, more glycogen capacity.  Glycogen is going to be the
fuel of choice during anaerobic exercise and so even though energy useage
per meter of forward movement is going to be higher with the larger horse,
the larger "gas tank" is probably going to be the deciding factor.  There
are circumstances where the second horse would win, but most times, the
first horse has it, no question.

So I agree that tiny hineys on big horses are very often going to win the
race, especially on the flat.  If for no other reason, because endurance
races are more and more becoming fifty or one hundred-mile sprint races,
where glycogen reserves are the deciding factor.  At Tevis, that was NOT the
case---probably because the course is narrow, mountainous and technical
enough to mediate most of the sprint advantage the tiny hineys have over the
heavyweights.

My point in all of this continues to be that there are alot of energetic and
biomechanical factors to consider besides *just* how much the rider weighs.

Susan G



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