Re: RC: Fast Twitch muscles cells and QHs

[Kim <kim@redhorsetech.com>]

Hope you don't mind if I make some clarifications to your post... :-)


On Thu, 9 Sep 1999 10:24:58 -0700, "guest@endurance.net"
<guest@endurance.net> wrote:
> I recall a RideCamp discussion awhile back about Fast Twitch
> (FT) and Slow Twitch (ST) muscle cells. (There's some medium
> twitch too, but we won't get into that).


"Medium twitch" are pretty important, so if it's okay, I'll volunteer to
explain them a bit.

This type is usually referred to as "fast twitch, high oxidative" can be
*thought* of as a fast twitch in nature, except that they can be
conditioned to work in a more aerobic environment and utilize fats for
fuel, just like the slow twitch.  This is how your Quarter horse can
"transform" from a bulky sprinter prospect to a descent (or better :-))
endurance horse... condition those slow twitch and fast twitch high
oxidative cells to their fullest aerobic capacity.  Sprinters depend
primarily on conditioned fast twitch cells during work... endurance and
CTR horses excel using conditioned slow twitch and fast twitch, high
oxidative cells.  

But both horses will use the "other types" of cells as well.  For
example, a horse at full speed is using every cell possible... the slow
twitch cells are not being spared just because they prefer oxygen-rich
environments.  That horse has gotta move, and will use everything
available to him to accomplish that goal.


> Most QHs, without thoroughbred blood are born with about 96% FT.
> Most prue-bred Arabs are born with about 96% ST muscle cells.


I happened to post the following data on the CTR list just this morning
(the same discussion is going on over there).  Appologies to the CTR
folks who've seen this before... you can throw a rubber brick at your
monitor now 'cause you're tired of hearing from me (eg)!

Note: FT= fast twitch, FTH= fast twitch high oxidative, ST= slow twitch.

Arabians:   20% ST,  50% FTH,  30% FT
Standardbreds:  20% ST, 50% FTH, 30% FT (nope, not a typo... just like
the Arab :-))
Thoroughbreds:  12% ST, 53% FTH, 35% FT
Quarter Horses:  8% ST, 50% FTH, 42% FT
Ponies:  20% ST, 40% FTH, 40% FT
Man (mid-distance runners): 60% ST, 35% FTH, 5% FT

Top endurance horses:  40% ST, 55% FTH, 5% FT
Top sprint horses:  6% ST, 54% FTH, 40% FT
Heavy hunters: 30% ST, 35% FTH, 35% FT

(Biopsies taken in the middle gluteal muscle below the tuber coxae in
equids)

So, the QH really doesn't have only 8% slow twitch... what he has are 8%
*dedicated* slow twitch, and 50% of these other types of cells that can
be conditioned to work more like slow twitch when needed.



> 
> IMO, it takes about 3 to 4 times longer to condition a pure-bred
> cold blood, as it does a pure-bred hot-blood.
> (This has been my experience... and would like to hear from others
> that have conditioned hot and cold bloods).


Several of us have found that the QH crosses will take about twice as
long to condition under a conservative conditioning program.  The FTH
cells need to be "trained" to work as a slow twitch cell, but a longer
conditioning program is certainly not a bad thing.  That's more time for
proper bone restructuring, bomb-proofing, and so on.  You really get to
know your horse.  The one real bad thing is overdoing it and having the
*wonderful* result of overtraining.  Then it's vacation-time.  However,
the optimal amount of conditioning time varies with each individual, no
matter the breed.  

It is really neat to watch the bulky critters "transform" into leaner,
flatter-muscled atheletes... when Lee was in her conditioning program,
many of the fellow stable boarders did not recognize her (yup, you tend
to find out which people only go out to see their horse only once a
month, LOL)!

Hope the information helps a bit... 

Kim (and Lee, the QH mutt)


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