Now, fatigue is certainly important to avoid, but your recovery heartrates
are what will tell you how hard you are testing your horse. If, within 60=90
seconds after "crossing the finish line", your heartrates are under 110, you
really haven't challenged the oxygen delivery system. Recovery numbers over
125 indicate a significant lactate challenge. Over 135--that's a bit much for
today.
Remember that until you're 2 1/2 miles of strong lope into a workout, you're
still going to have emotional artifact--anywhere from 20-40 points. Part of
what I'm calling "emotional" may just be spinup of circulation--but you can't
count 158 heartrates as work until you're well into the exercise. Our
racehorses gallop ontrack at anywhere from 160 to 180. Most aren't challenged
at all with heartrates of 190.
However, when heartrates exceed 210, then you can count on the parabolic
lactate curve to be well underway--that is, lactates are rising, and fatigue
approaching, very quickly. Two minutes of this kind of work is a solid
challenge for a fit racehorse.
Hills will produce big heartrates that are fairly honest heartrates, in terms
of impending fatigue. So the hill bouts should be relatively short if taken
at a gallop--300 to 400 yards, 3-4 repeats. Only workouts that challenge the
cardiovascular system significantly will produce beneficial changes in oxygen
delivery and uptake. Long slow work, carried to an extreme, will do not much
more than challenge the fueling systems. This is beneficial, but attacks only
part of the problem.
It is my guess that fatigue in the endurance horse, in competition, is a
muscle fuel problem rather than an oxygen (aerobic) problem. In fact,
alkalosis is probably a bigger problem than lactic acidosis. However, you'll
want to ensure that the working muscles are very well vascularized--and
that's where the higher heartrate workouts will come in very handy.
Finally, no matter what your end goal, or when you MUST reach it, everything
has to be brought on a slice at a time. No surprises. Example of a surprise:
last week you galloped up this grassy knoll at a medium lope 4 times with
heartrates ranging from 180 to 200. Today it rained and the grass is
slippery. If you work the hill at the same speed, the same number of times,
with the hind end throwing up gouts of dirt, you'll probably injure a
shoulder.
Why work hills in the first place? One reason: no matter what breed you're
riding, the horse will have a significant percentage of fast twitch muscle
cells. Hills will use these cells if you take them with some reasonable
speed. In a long endurance race, you'll be using slow twitch cells almost
exclusively. But at a certain point, your horse will begin getting low on
fuel in those muscle cells. If your fast twitch cells have been well-fueled
with resistance exercise (hill work) then you can sprint the horse a quarter
mile occasionally and trigger the FT cells to burn their fuel and throw off
lactic acid. The lactic acid will then trickle down to the starving slow
twitch cells and provide a burst of new fuel.
Enough for now
ti