Re: RC: Tieing up

[CMKSAGEHIL@aol.com]

In a message dated 2/19/00 6:39:52 AM Pacific Standard Time, 
hn.heather@wanadoo.fr writes:

<< Ti wrote:
 
 > No. Athletic horses are simply not brought to the level of fitness that
 human
 > athletes are, so there is less fitness to lose. The fitter you get the
 horse,
 > the more easily that fitness will be lost with time off.
 
 So when we hear the horse described as a "natural athlete" are you saying
 that this is not true? >>

Perhaps the difference in what horses can do naturally is genetics??

Just one note on natural athleticism (since heart rates, cardiac output, et 
al has been a discussion topic):

One can pretty well graph all mammals on a straight line graph as to how much 
they can raise their heart rate without beginning to diminish cardiac output. 
 (If you recall, cardiac output is the product of heart rate times stroke 
volume.)  What happens when the heart rate passes a certain point is that the 
heart does not refill completely between beats, hence the stroke volume 
declines, and the cardiac output actually begins to drop.  In virtually all 
mammals, this starts to occur at a rate about 4 times higher than the resting 
rate.  Big mammals have lower resting rates than small animals--these numbers 
are not precise, but for an example, an elephant has a resting rate of less 
than 20, and cardiac output begins to decline at less than 80, whereas a 
mouse has a rate around 200 or so, and can go up to 800.  The horse is the 
SINGLE exception among species that have been studied, as he can elevate his 
heart rate as much as SIX times over his resting rate, making his anaerobic 
threshhold considerably higher by comparison than other species, as he can 
get oxygen and fuel out to the muscle tissue at a much higher rate.  (If you 
want references, Tom, I'd suggest you go to vet school--learned this in 
Cardiology over 20 years ago, didn't give a rat's patootie about sources 
because being able to quote the reference doesn't alter the findings, but 
since you seem to be in disbelief when folks in the real world mention facts 
without the correct journal quotations, I'm sure the cardiology profs at 
school would be glad to oblige you--they were "into" that because they were 
an active part of academia themselves, but bless their hearts, they did not 
ask us to cite references on exams, nor did any of the board exams require us 
to cite references, either, so I didn't waste my time memorizing who 
discovered what.)

Just one of the genetic adaptations that makes horses such fabulous aerobic 
athletes, and the genetic variation within the species contributes even 
further to the potential of a given horse within the normal range.

Heidi