Re: Heartrate Threshold

["spencer" <spencer@inu.net>]

Biological theory based on scientific observation states that the smaller
the animal the higher the heart rate and the larger the animal the slower
the heart rate.  In adult humans, the more conditioned athletes have pulses
in the 40s routinely due to the more efficient heart muscle pump mechanism.
 Human Fetuses have a normal range between 120 and 160 and the decreases to
just over 100 after birth and slowly decreases until adulthood.  Some
medical conditions can make the rate be less than the normal adult rate of
60 to 100.  But the overall picture needs to be looked at whether human or
horse is being evaluated.  I doubt that an electronic monitor could get any
kind of accurate rate over 200 and defiitely not very accurately by
palpation or even with a stethoscope.  that is experience speaking, mostly
with humans.  Mary Ann, Tx

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From: Susan Evans Garlinghouse <suendavid@worldnet.att.net>
To: Tivers <Tivers@aol.com>
Cc: fmechelh@c-s-k.de; nitram@gv.net; ridecamp@endurance.net
Subject: Re: Heartrate Threshold
Date: Sunday, May 17, 1998 1:23 PM

In general, the ability to develop a high RPM is
> good in the athletic horse--but when you get up around 240 you're on the
> ragged edge of fibrillation and there may not be enough time between
beats for
> ventricular refilling.
> 
> ti


I don't know whether this would apply to horses but there are other
species that have MUCH higher heart rates---rodents get up around 600
bpm all the time, and although obviously much smaller, the physics of
pressure and ventricular filling are the same.  I think I read somewhere
that hummingbirds have a normal HR of around 2400 bpms, although their
heart is a little different.  So I'm not so sure a horse's heart
wouldn't be capable of re-filling and pumping out a fresh load of blood
at 240 bpms---after all, it has been documented on more than one
occasion.

Susan