Horses aerobic energy capacity

Question
Hi Don!

I don't know much about the energy expended by horses in races but understand from reading that ... in sustained exercise, the horse's oxygen uptake and expended aerobic energy increases linearly as the intensity level of exercise increases; until they reach their maximums.

That makes sense since it's related to heartbeat rate and blood flow but I can find nothing relating to how quickly these things (heartbeat rate, oxygen uptake, etc) increase under racing conditions where the level of exertion is at a maximum from the starting gate.

Any and all insights would be appreciated but I'm especially interested in your thinking as to how long (in strides, time, or whatever) it takes for the horse's heartbeat rate and oxygen uptake rates to reach their maximums.

Thanks!

Regards,

Bob  

Answer
Hi Bob,
      This question is probably better answered by someone more experienced than me.
As its a scientific question and the answer you are looking for is probably some sort of formula, it might be better to direct it to a local university specialising in Thoroughbreds.
You are right in your assumption that the horses heartrate will increase as the pressure goes on during a race, however the type of race and tactics will have an influence.
In a sprint race they will sprint from the start however in a distance race they may not sprint at all!
It's interesting to note that race times don't vary much over time and any improvement can often be easily explained by the improvement in the tracks we are now racing on.
I'm sorry I can't be more help here as this is an intriguing question. I suspect that if you can develop some sort of formula you will become a rich man!
Good luck,
Don Boddie