The first horse delivered his second mile at a 207 heartrate followed by an
88 recovery heartrate--the horse stood still for 70 sconds and his heartrate
plateaued at 88--it would have dropped further with a longer rest, but we
catch the recovery heartrate and then go on into warmdown. The second horse
delivered his second mile at a 231 heartrate and demonstrated a 110 recovery.
Neither horse showed distress, emotion, or fatigue at any time during the
entire procedure.
We took five minute post-ex bloods on each horse and analyzed for lactic acid
using a YSI Sports 1500. The first horse showed a 1.42 mmol/l lactate, the
second a 4.17 lactate. The principal difference between the two horses,
pre-exercise, is that the first has had a lot more exercise at elevated
heartrates than the second. The owner of the second horse is in a comparative
hurry, and we try to accommodate our owners to the extent that the animals
are working well within themselves and are in no danger. Hopefully, the
second horse will catch up with the first, in terms of racing fitness.
At any rate, we can say that the second horse was working on the edge of his
LA4 threshold while the first was working well below steady state. We can
say that despite the high heartrates of the second horse, he was fully
capable of another interval mile at an increased speed without fear of
metabolic compromise and resulting fatigue. The first horse did not get much
of a challenge with this workout and we're going to have to upgrade his
workload substantially before he does experience a significant cardiovascular
challenge.
This should add more perspective to our discussion of LA4.
ti