Re: Carbo loading products

[Tivers@aol.com]

In a message dated 1/6/99 9:51:14 AM Pacific Standard Time,
suendavid@worldnet.att.net writes:

<< Sure---but endurance is a relatively low energy exercise on a
 minute-by-minute basis, at least compared to horses in your world.  The
 big energy bill for endurance horses adds up because they do it for so
 long, right?  So FFAs *should* be preferentially used for the bulk (ie,
 65%) of the work, simply because they're in almost endless supply, and
 conserve the glycogen to keep supplying the pyruvates for ATP turnover,
 and hopefully, provide an extra kick of rocket fuel when needed and when
 the FFAs *won't* be helpful.>

At this point, it's philosophy as to what percentage of the endurance horse's
work is satisfied by FFAs alone. The fact that we're getting benefits from
periodic carbo supplementation during a ride suggests that carbs are far more
important than many in the sport think they are. How much more important is
unknown at this point. Certainly, carbohydrate supplementation in endurance
horses is not the Devil's Work as Matthew and some others have suggested.   
 
 
 > Glucose levels are never consistent--they're all over the place. What you
mean
 > is a sustained elevation of blood glucose as opposed to hypoglycemia.
 
 Yes---and also sparing liver and muscle glycogen stores as possible,
 especially during multiday rides.>

A red herring. Instead of doing loopdeloops trying to spare glycogen, why not
just feed it????  
 
 
 
 > Have you ever seen the muscle biopsy studies demonstrating that a horse can
 > work for hours, come back exhausted, and still have nearly 100% of the
initial
 > glycogen content in FT muscle cells--it's a horse study, one of the early
 > ICEEPs, Sweden or San Diego.
 
 <Depending on the type of exercise, that's not too surprising---sustained
 endurance type exercise will preferentially deplete the slow twitch
 fibers with little depletion occurring in the FT.  During hard, intense
 exercise, it'll be the other way around.>

Yep, but periodic bursts of higher intensity work, during an endurance ride,
will trigger FT and FTH muscle cells to fire, using their stored glycogen
(weight the horse is carrying around) and throwing off some delicious lactates
for the ST cells to gobble up.
 
 
  Bursts of speed, or aggressive hill climbs can be
 > very benefical in the endurance horse, mobilizing that glycolytic pathway
and
 > providing a lactic acid cascade to the oxidative pathways for additional,
 > fast-acting fuel.
 
> Well, I'm not sure I want to rely on lactates as a fuel source too much
 during a ride, simply because overdone, you're also disrupting the
 cellular environment and compromising immediate performance, a bigger
 issue than providing another fuel source.>

Try it. You'll like it. Field tested and already demonstrated.


 >But I have no argument with
 using fartleks during training to condition the FT fibers, as long as
 it's not done so much as to start to influence the type IIA fibers.>

The influence on IIA fibers with be to increase oxidative capacity, converting
them, to some extent, to IIB fibers.
 
 > >  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.>
 > 
 > Pretty foolish to me, too. Who said that? What I said was that glycogen had
to
 > always be available in significant quantities and that blood glucose should
 > remain significantly above fasting levels. This is easy to achieve with
 > periodic feedings of easily absorbed carbohydrate.
 
 Then we're agreed.
 
 Have a good trip.
 
 Susan G
 
Good, we're beginning to understand each other.

ti