Thanks for the data points!
Now, given that high lactate numbers are not a real concern, we're back to
"what causes endurance horses to get tired?" Next most likely culprit: muscle
fuel depletion.
We have three fuels to play with: fats, proteins and sugars (glucose in the
blood, glycogen in the muscle). One of my observations in racehorses is that
trainers seem to be overly concerned with the weight of their horses--then
want them skinny, with a deep poverty line, backbone and hip bones sticking
out, etc. These trainers feed no carbohydrate on race day. The characteristic
run of such a horse is plenty of speed up front, then severe,
injury-producing fatigue coming on about one minute into a race. These
failing racehorses also display relatively low post-race lactates (compared
to the winners, at least) and high muscle enzymes (indicating muscle damage
during the race).
I've also noticed that the competitors in the great classics are, for the
most part, "plump"--loaded with fuel, in my mind. I've heard from competitors
in all equine sports that other folks are calling their horses "fat", even
after they've won the competition.
When I send a reasonably fit horse to the racetrack, I often hear from the
owner that the new trainer has said that the horse is "too fat" and needs to
lose 150 lbs before attempting speeds the animal has already performed--in
multiple heats--at our training venue. Some years back I read an Irish paper
that said that the most unfit of equines carried, at most, about 25 lbs of
adipose tissue (this conclusion via autopsy dissection). So when the track
trainer wants to take 150 lbs off my trainee, I imagine 10 lbs of fat loss
and 140 lbs of glycogen, water and muscle tissue going down the drain. And,
along with it, performance.
Experiences? Comments?
ti