IMO, there is NO excuse for putting that kind of strain on a baby.
I personally can't stand horse racing for the fact that these trainers are asking 2 year olds, whose bodies, joints, tendons, and minds are still developing, to run hell bent for leather for a mile or more. I don't care HOW much you "condition" your 2 year old, this is simply too much, and this is why you see such tragic breakdowns on the track. One more year and these colts will be much better suited to handling the stresses of racing and might have a chance at a longer career...I also have issue with their so called "training", but I will save that for another rant.
Similarly, I have issue with these "big time" show people who are forcing their babies into training way too young, and to perform long before they are physically or MENTALLY ready for such demands, all for the sake of the that shiny buckle, trophy saddle, name in lights, and/or the $$$ they might get....
There is no excuse for this. None. If you're more concerned with getting to the pay window, than what you're ultimately doing to the young horse that you MUST start as a long yearling to make it to the futurities, then you need to find something else to do that doesn't involve pushing a living, breathing being into the dirt to get there.
*stepping off my soap box now*