Tortoise vrs hare, ie: carbo vrs fat!

[Sarah Ralston <ralston@AESOP.RUTGERS.EDU>]

Welcome Back, Tom. Glad to hear you are well again and very active! Heidi
and Mike-it is like old times! forgive me for wading in a bit late, but it
is the end of the semester-exams and termpapers to grade. Also
I'm going to try to avoid the point/couter point approach. 

Another word of caution again however from the "other" camp regarding Tom's
predilection for carbo loading. Please note that he said in his first
message that the "endurance" races in Dubai where they were showing
promising results were flat, sandy and FASTER than most of the ones here,
and in his response to Beth and others he admitted that if carbo loading
you need to do it every two hours during a race. I can see where this would
work and do not argue with it. However, this strategy is not the only one
that works and yes you should be concerned about sudden increases in
insulin inhibiting fat utilization if not continuously replenishing the
glucose (which lacking "on board" glucometers and carrying the specially
formulated rapidly acting carbo loads with you and/or reaching pit stops
every two hours could be tricky). Tom openly has admitted that the high
glucose/insulin regimen he promotes will inhibit fat utilization but this
is mainly because insulin inhibits lipolysis, not that it blocks the krebs
cycle. In a long HARD (read lots of climbs and caution needed on the trail)
ride like the Tevis, one of the reasons Susan's work on body condition
showed that horses carrying a bit more weight (body fat) with condition
scores of 4-6 did better was that they had the fat stores to burn! The
really thin horses with no fat stores pooped out, and they may have
benefitted from Tom carbo feeding at 1 1/2 hour intervals to keep them
going because they had no gas in the fuel tank! If not racing to win a 7
hour 100 mile race, but going a (IMHO) more reasonable pace with a well
conditioned horse, the utilization of fatty acids (read lots of hay, beet
pulp, green grass and fair amount of body fat) is efficient, safer and
cheaper than carbo loads. Under aerobic conditions the utilization of the
VFA's (a capability human athletes do NOT have) and fatty acids from body
fat mobilization help preserve the blood glucose concentrations at the
level necessary. Yes glucose is necessary but using the alternate fuels
available especially to the equine athlete avoids the peaks and valleys! 

I also do not and never have recommended feeding high fat during a ride,
but there is a place for fat supplementation during conditioning,
especially if the horse tends to be a hard keeper. But again, "high" fat in
a horse ration is only 7 to 10 % of the total-a cup or two max per day, not
the excesses that inhibited performance in the rat and human literature.
The work done by Potter in Texas showed that horses adapted to high fat
diets (it takes up to 3 months for them to fully adapt) were more efficient
than those on lower fat rations. They conserved blood glucose levels better
than low fat fed horses because they utilized the VFA's and fatty acids
from fat mobilization better, a trick human metabolism just doesn't have up
it's sleeve.

I leave the cutting edge, pushing the limit fastest race horses to Tom. My
voice is for those of us who ride to complete with a healthy, sound horse
that will serve us well for many, many years with no desire to push it to
or over its limits. 

I will not get into another war with you, Tom. Just wanted to point out
that there are different requirements for different strategies-your
recommendations excel at fast and furious, the hay/beet pulp and green
grass strategy preferred by many others (some of whom have also competed
very successfully for years on the same horse!) tend to do better with the
slower and steadier pace often required for not so flat rides. So,
Ridecampers, decide which strategy you prefer and follow that! I do not
disparage the "hot shoes"-more power to them-they certainly do add
excitement to a competition. Just remember that many of us in this sport
are not and have no desire to be hot shoes and that the level of
horsemanship, training and resources it takes to be really cutting edge
competitors is beyond the ability of most newbies (not that they couldn't
progress to that stage eventually). Carbo loading during a ride may work
for the elite endurance race horses, but if used improperly and/or by
inexperienced riders, could end up in more "boinks". It is also absolutely
not necessary for the competitive trail types of rides where the pace is
controlled to a modest (compared to your hares) 6-7 miles per hour. 

Again, Tom, you keep on finding the recipes for the hares but leave the
tortoises to Sue, Heidi, Mike and me!

Sarah Ralston and Fling (who competed over 260 miles in three months this
year without metabolic problems, despite some really extreme weather
conditions. Unfortunately a pinched nerve (as it turned out) which caused
on and off lameness (which of course appeared on during the trot out!)
prevented her completing the last day of both the NJ 100 and NY 100. Sigh.
If it ain't one thing it's another...)

Sarah L. Ralston, VMD, PhD, dACVN
Associate Professor
Department of Animal Science
Cook College, Rutgers, the State University of New Jersey
84 Lipman Drive
New Brunswick, NJ 08901

Ralston@aesop.rutgers.edu
732-932-9404


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