Re: carbo during exercise

[Tivers@aol.com]

In a message dated 1/5/99 3:10:59 PM Pacific Standard Time, lb@nismat.org
writes:

<< Well, now I've got to jump in the discussion.  It seems that giving 
 1 ounce of carbohydrate per hour to a horse DURING EXERCISE  is being 
 called "carbo loading", a takeoff on what human athletes do.  Of 
 course, this is not at all carbohydrate loading.  Carbo loading 
 refers to altering the normal diet to one that supplies a higher 
 percentage of carbohydrate for SEVERAL DAYS prior to competition. >>

Right. And most who have tried that report back that their endurance horse is
not much fun to ride at the beginning of the competition--too aggressive. Same
thing's happening with the first day of Combined Training--the horse wants to
jump tall buildings. 
 
> The purpose of such a regimen is to encourage atypically large 
 amounts of glycogen to be stored.  By supercompensating the muscle 
 with carbohydrates, exercise duration can be extended.  In SOME 
 studies in humans, at least.>

We see extended high speed performance in TBs and SBs, suggesting that is the
case in racehorses.

>  Assuming that we all understand that giving 1 ounce of carb per hour 
 to a horse during exercise is NOT carbo loading, we should evaluate 
 how such recommendations have come into being.>

The protocol that seems to be working is 2 oz every 2 hours.

>  In humans and 
  in rodents, providing carbs during exercise simply provides an 
 exogenous source of carbhohyrate.  It has been repeatedly been shown 
 in these species that carbs during exercise have the effect of 
 sparing the limited muscle glycogen supply.  Such dosing regimens 
 have quite consistently been shown to extend the time to fatigue, as 
 opposed to fasting during the exercise bout.  In humans the 
 recommendation is 1.5 -3 ounces of carb per hour during exercise.>

That's interesting. Maybe more would be better in the horse--we're feeding 4
oz 2-3 times a day (depending on the size of the horse) for four days in
racehorses.  
 

>This is not enough energy to meet their total caloric exercise needs, 
 by any means,  but it does offset their expenditure.  It would seem 
 to me that all discussions regarding carbohydrate intake during 
 exericise in endurance  horses is moot until someone does research 
 which demonstrates:
 
  1) that glycogen is severly depleted in endurance 
 horses at the end of an endurance ride when animals are fed typical 
 foodstuffs; 2)  that providing horses with  such small amounts of 
 carb during exercise [1/2 that recommended for a 150 pound man] 
 actually spares use of muscle glycogen to a statistically significant 
 degree 3) that enhanced glycogen levels actually allow horses to 
 perform for a longer time at the intensities typical during endurance 
 events. 
 
 Well, off to the land of ice and snow.  Urrrhhhhh winter!!
 Best to all,
 
 Beth Glace MS >>

I'd like to see that study done. We've been very conservative in our dosage
recommendations. Still, we're getting good reports back. One thing I wonder is
whether bigger doses would make the horse aggressive--like they are after
glycogen loading. Not good on a mountain trail. the more reports we get, the
easier it's going to be to zero in on the ideal dosage. 

ti