ridecamp@endurance.net: Re: carrying weight and the ROC study (long)

Re: carrying weight and the ROC study (long)

Gayle Ecker (gecker@uoguelph.ca)
Thu, 25 Sep 1997 13:13:15 -0400 ()

Susan wrote:
>There was a nifty study done several years ago at the ROC that measured
>weight loss in individual horses through the ride---weighing the horses
>numerous times throughout the day and afterwards.
>I don't have the study here in front of me, but I seem to remember that
>the more successful horses lost less weight throughout the day than did
>horses that pulled or finished at the back of the pack
> As in the results of my previously described study, it would
>seem that there are instances in which carrying more weight on the horse
>in the form of water weight, a little body fat, etc., seems to be an
>advantage.
>I can't remember who the author was,
>might have been Gayle Ecker from Guelph, who's lurking on the list
occasionally.

Dear Susan and List Members,

Thanks to Susan's prodding, I've just de-lurked! : )

Susan, you may have been referring to the 1993 study done by Mike
Lindinger and I at the ROC, and yes, there was a clear correlation between
the weight loss at the first vetcheck and finish time. Water losses at
the first vetcheck (20 miles) were between 5 to 25 litres, with an average
of about 18 litres. The horses that lost only small amounts of weight
early in the ride finished faster. Horses with large weight losses in the
early part of the ride finished slower. The same trend showed up at the
halfway check, but due to higher variability this was not statistically
significant. It is certainly of practical and physiological significance
for the horse and rider, however. As a group, the slower horses had lost
about 2 times the total body water than the riders finishing in the top
20.

In our database on almost 300 endurance horses, this holds true for horses
at other rides as well. Overall, horses considered higher level
performers lost less weight early in the ride than those finishing with
slower ride times. This should not be that surprising. The water deficit
compromises the body's ability to keep the muscles working at optimum, to
keep the body cooled out due to reduced blood volume, may impact on the
functioning of the gut with less efficient absorption of water and
electrolytes and various other things that impact on performance. The
longer the deficit remains, the harder it is for the horse to keep going
at the same speed. In other words, trying to "catch up" the deficit while
still working is very difficult on the body. There are conflicting
demands on the diminished blood volume and the horse must slow down or
health problems can develop.

So, yes, there are definite advantages to carrying more weight, when it is
water in the gut of the horse, or perhaps more correctly, there is a
definite disadvantage to reducing the weight when the weight loss is due
to a loss of body water. (Having an optimal %fat is needed too. For
energy and proper functioning, too much of course, then too much weight is
carried and the horse has a harder time dissipating heat.)

There was another point of importance from the ROC. Horses that preloaded
with electrolytes prior to starting the ride had lower deficits of
electrolytes early in the ride. This is why Mike and I suggest that
preloading is beneficial when it is done properly. At the next ROC we
attended to carry out research, we could not do this analysis as almost
every rider in the study had preloaded in some way.

We have just finished doing research at another endurance ride here in
Ontario, where we did full profiles on the hydration and electrolyte
status as well as collected sweat from the horses using a new method
with improvements. We also collected information on the electrolyte supplementation
of each horse and calculated the amount of electrolytes going in, the
amount of electrolytes and water going out (through sweat) and how much
was left in the horse. Fascinating information! There are clearly some
improvements that can be made with certain supplementation regimes to
individualize programs for the horse and hopefully optimize performance.

All the best,
Gayle

Gayle Ecker
gecker@uoguelph.ca

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