Well, it turns out this is the subject of my thesis project, so thought
you might be interested in some of the horse/rider weight ratios we
collected on approximately 450 horses the last two years at Tevis.
The average weight carried by successful Tevis completers was 20.43% of
the horse's body weight. The average weight carried was 181.48 pounds.
The lightest load carried successfully was 14.9%, the heaviest load
successfully carried was 30.71%.
The average weight carried by Top Tenners was 180.7 pounds, and the
average rider weight ratio was 20.3%. The Top Ten horses averaged 892
pounds.
There was no statistical difference in weights carried between the
horses that finished and those that were pulled. There is also no
statistical indication that horses carrying less weight finish any
faster---as a matter of fact, several of the Top Ten finishers in both
years were among the heaviest riders.
What turns out DID make a significant difference was how much body fat
the horse was carrying during the ride---or body condition score as has
been previously discussed in earlier threads. Horses that were scored
as being very thin AND were carrying heavy weights consistently turned
out to be the first pulled. Thin horses carrying lighter weights were
pulled next often---they on average made it farther down the trail, but
almost every one was pulled before the finish.
Horses that were in good body condition---no ribs sticking out, no
pointy hips and spinal processes showing---were by far the most
successful group of horses to finish the Tevis trail and in these
horses, how much weight the horse was carrying made no difference as to
how well they placed. During data collection at Wendell Robie Park, I
remember looking at several horses who were past Tevis winners/Top
Tenners/Haggin Cup winners (and were again that year) and noticed none
of them looked like what you'd expect in an endurance horse---they were
all hard as rocks, but none of them were ribby-looking at all. A few
looked downright chunky.
The conclusions drawn from at least this particular study was that
horses are capable of carrying weights in excess of 30% of their own
body weight for 100 miles, IF the horse has sufficient body fat to
supply the ongoing demands for metabolic fuel. The thinner a horse is,
the quicker he is going to run out of energy in direct proportion to how
much weight he has to carry.
BTW, there'll be a complete article on this project in this spring's
Tevis Forum that will include more specifics and hopefully explain the
differences between "too thin" and "not too thin" a little better.
Hope this helps some of you.
Susan Evans