Horses are so very unique to humans when it comes to exercise physiology.
For instance, no human is born able to run a 4:00 mile, they first have to compete and train through 8 minute miles, then 7, then 6, etc. until they reach their physical peak, which may never be a 4min pace. This entire process revolves around what is called progressive overload: progressively challenge the body's systems with just a little more work, allow for recovery, and get faster.
Thoroughbreds however, are born and bred to run the equivalent of a human 4 min/mile, let's call it a 12 second furlong. String 12 of those 12 second furlongs together in a row and you have Secretariat, which these days means a $50 million dollar plus animal in the breeding shed.
But, conventional training methods don't always develop the approriate stamina, or endurance - rather they rely on breeding to dictate race performance.
Rating thoroughbreds to allow their internal systems to grow to support a 3:00 mile, then 2:45, then 2:30, etc. is the best way to help them realize their full athletic potential while assuring optimal levels of soundness along the journey.
You may never get a Secretariat, Big Brown, Curlin, or Triple Crown winner, but you can make your $10k claimer the winner at his local track.
Shoot, already running out of time...Next post will detail the precise role that heart rate zone training plays in the process.