Body fat and endurance

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

Beth wrote:

>Nonetheless,  body fat was directly correlated with finish time:  
>higher body fats, higher [slower] times.  Furthermore, for both men 
>and women, non finishers weighed significantly more than finishers.  
>the race this year was extremely hot, around 100 F, so the extra 
>weight probably impaired thermoregulation.  However, we found similar 
>results last year when conditions were far more moderate.  

I think this actually accentuates the difference between the equine and human 
endurance athlete. Susan's work also found that the overweight horses did
poorly.
However it was a bell curve effect. The lean mean racing machines that tend
to do best are those fit 
horses with enough body fat to cover their ribs but not so much you can see
the ribs when the horse takes a deep breath, loins that did not have the
back bone sticking up but were either flat or slightly 
slanted /\ and withers and necks that did not look obviously thin: a fair
amount of body fat but not rolling in it. A condition score of less than 4
(most TB racehorses when racing fit are closer to a 3 because they don't
need the reserves for the long haul) and over 6 (most show horses and
dressage horses are 6-8) was associated with a higher percentage of
failures. I wish Susan would get back on, because she could give the
details. IMHO, if a skinny horse did do well it was probably on carbo
supplements at 1 1/2 hr intervals!!

 In surveys of endurance horse nutrition, most are fed primarily forage diets,
which in view of our previous discussions, means the horses are geared
toward the utilization 
of VFA's and fats. Humans do not have the huge nutrient resevoir in their
lower bowel that the horse has in its large colons. Human athletes rely on
their Power bars and high carb snacks in such competitions, putting
the emphasis on ti's beloved carbohydrates and preventing the heavier ones
from drawing upon their body fat as a fuel. The CHO supplements do turn
body fat into sludge in such instances! Horses, on the other hand, can
cruise along drawing from their colonic resevoir and fat reserves, so long
as that utilization is not blocked by sudden surges in insulin and assuming
they have the reserves to draw upon! Until recently very few people fed
significant amount of grain or high simple carbo to horses on the rides. 

Interesting comparisons, Beth!

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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