Ridecamp: [RC] weight aint that simple (was Mad Science)

>So, I don't see how your comparison with a Subaru and >a supercharged 454
dually (you must be doing very well >btw to own such a vehicle, lol) equates
to my heart rate >study.  I'm not comparing two different horses, I'm just
>comparing the heart rates from the same horse with two

The point I was trying to make was that you need to look at alot of things
besides just rpms to determine strain on the system.  But, read on...



>  I really don't think it's that far fetched to think that a >heavier rider
makes a greater demand from a horse.

Nope, it isn't.  BUT, there's alot more to it than just measuring oxygen
demand (which is what you're really measuring with your HRM experiment.
Yes, you add more weight to the total system and it takes more energy to
move the horse forward.  That makes a big difference if you're sprinting
flat out for six furlongs.  Over fifty or a hundred miles, the differences
flatten out enough that it makes very little difference.  In fact, the
energy requirement difference between the same horse carrying a 160-lb rider
versus a 210-lb rider over a fifty mile course is only 9%.  Again, if you're
sprinting the entire thing, it matters, mostly because your energy
substrates and available supply of both is an issue.  If you don't happen to
ride under the belief that the second place horse is the first loser, than
the energetics aren't enough to matter.

So let's look at weight a different way.  Instead of putting a heavier rider
on the same horse, let's say you put an extra fifty pounds of weight onto
the horse himself instead.  That should raise his heart rate as well and be
a hindrance, right?  But you can't say that necessarily, either.  If the
horse is underweight and in negative energy balance, then that extra fifty
pounds of weight is much more likely to improve his performance enormously,
including lowering his heart rate rather than raising it.  I have data on
about a thousand hundred mile horses to back that statement up.  What if you
put fifty pounds onto the same horse, except that now he's on the chubby
side, plus rode him in hot, humid weather?  No doubt about it, that extra
fifty pounds is going to just add insulation and make it more difficult for
heat dissipation to occur.  In that case, heart rate is going to rise.

Another example---if you've done a good job preparing your horse for a ride,
you've done everything you can to stuff a bale of forage down his face and
got him so full of water he's sloshing.  Between total gut fill and water,
that accounts for roughly 200-300 lbs of weight in the GI tract.  Lotta
weight.  So we could improve performance enormously by not feeding the horse
for a week before a ride, right?  Anybody here wanna raise their hand if
they thinks that's a good idea for an endurance horse?

So, don't worry Howard, I'm not arguing with you, just debating something I
happen to find interesting.  Weight does absolutely make a difference---it
adds to the heat load, adds to biomechanical stress, adds to energy and
oxygen requirements.  No worries there.  I think the take-home point of any
research project---from yours up to the million dollar projects---is the So
What factor.  What's the take home message?  Does the extra ten heart beats
per minute (or whatever) matter in the big picture?  Is the winner of any
race going to be the one with the lowest heart rate?  Nope.  To an endurance
horse, there are so many other factors besides weight affecting the total
picture, that you just can't take one single parameter (like HR) and make a
sweeping conclusion from that.  It just aint that simple.

But, I truly applaud you for having the curiousity to look at things like
that.  It was that kind of curiousity of wanting to know If and Why that
keeps most of the crazed researchers out there going. :-)

>  If BTW, is Howard the bull still a bull, or is he now a steer?  Just
curious.

He went home, minus gonads.  Let that be a lesson for you.<g>

Susan G




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