In theory, race training should be conceptually (though certainly not physically) the easiest form of training in ponyplay: teach your pony to run as fast as he can.
However, there are several nuances to training your pony to race. In addition, if you are emulating bio-horse racing, there is a wide variety of specilized tack that can be used to reproduce the race horse aesthetic.
You have two main sources to emulate here: First, the world of human sprinters. Second, the immensely large world of (bio-)horse racing.