Re: Carbo loading products

[Susan Evans Garlinghouse <suendavid@worldnet.att.net>]

Tivers@aol.com wrote:

> Problem is, at the most, fat will provide only about 65% of the necessary fuel
> no matter what you feed--so have you calculated the Mcals necessary from carbs
> and proteins to finish that 100 miles?????

Sure, I can do that.  Let's take a 950 pound horse carrying 175 pounds 
that finishes a 100 mile ride in 20 hours of actual riding time, hardly
a world championship pace or unusual weights.  Ignoring variables such
as as inefficient movement on the part of the horse, skill of the rider,
etc, according to my calculations, the horse is going to burn 39 Mcals
of energy at the cellular level.  By the time you allow for digestive
efficiency, that's roughly four times what he needs on a daily basis
just for maintenance, right?

So, based on 4.15 Mcal/kg and 4.65 Mcal/kg from glycogen and proteins,
respectively, (call it 4.4 Mcal/kg average), if you strove for and
relied primarily on non-fat sources for energy as you proposed with the
rocket fuel analogy, then a horse is going to require about 19.5 pounds
of glucose and/or protein to fuel himself during that ride, and that's
totally ignoring the additional energetic costs for basic maintenance of
the body.  Personally, I have to work too hard to add body muscle and I
darn well don't want it burned as fuel, so let's just look at body
stores of glycogen.  Between liver and muscle stores of glycogen,
there's less than 16 Mcals worth of glycogen in the equine body, and
that's wringing out every last drop.  16 Mcals is only 41% of the energy
required for that 100-mile ride, so are you seriously proposing that the
rest of the energy can be provided as carbo supplementation during the
ride?  Allowing for 90% efficiency, you'd have to feed roughly 14 pounds
of carbocharge to supply the required energy.  Does that really seem
reasonable or practical, rocket fuel or not?  And that's just for a
back-of-the-pack completer with a lightweight rider.  How many pounds
would you have to try to stuff down the throat of a heavyweight horse
and rider trying for top ten? 

OK, so let's look at NOT forcing the energetic pathways to rely on
glycogen, let it just trundle along 65% fats and 35% glycogen like the
horse is evolved to do.  A horse in good condition has enough body fat
to ensure a virtually endless supply of fatty acids without running out,
so that's not even an issue.  That leaves 35% of the energy requirement,
or only 13.65 Mcals for the glycogen to supply.  Assuming the horse
starts out with a full tank, and continues to eat normal feeds
throughout the ride, then there's sufficient glycogen to supply what's
needed without carbo-supplementing---not tons of it lying around, but
for most horses, enough.  I will absolutely agree that in some horses,
maybe even a majority, performance might very well be enhanced by
supplementing, just to ensure that there *is* enough, and that plasma
glucose levels remain consistent and available---especially in horses
running closer to their anaerobic threshold and therefore using up more
glycogen and at a faster rate.  It's a great theory/practice when used
intelligently, really worth alot of further research (both field and
clinical) and is really an exciting development in endurance horse
nutrition.  But, I think ignoring the horse's basic energetic physiology
and forcing him to rely on glycogen as a primary fuel sounds pretty
penny wise but pound foolish to me.  At least for distance horses.


> 
> By the way, on your recommendation I did get Lon Lewis' latest book. Still a
> pretty bright fellow and certainly not in love with fat. I'll pull some quotes
> for you when I get back.

I'm surprised to hear you say that---his in-depth discussions of fat
supplementation for equine athletes seems to pretty strongly support it
for numerous reasons.  Quite clearly and succinctly.

> 
> Meanwhile, you can only deny your own experiences for just so long before you
> realize that something's wrong with your calculations. What's wrong is the
> underlying premise.

Well, as always, we may just have to agree to disagree---I agree that
carbohydrate supplementation is helpful to some horses...but the
operative word there is *supplement*.  The hard numbers just don't
reasonably support your theory in practical application.

Seeya,

Susan G