Performance Limited by Genetics

In a lecture at the 2007 Alltech conference, Dr. Ernie Bailey of the University of Kentucky explained that about 30% of racing performance in Thoroughbreds is due strictly to genetic make-up, leaving about 70% influenced primarily by other factors (age, track surface, training, nutrition, and so on).

In humans, there are over 150 genes that directly affect athletic performance; this number is not known for horses. Also, almost 20% of adult humans have a mutation that prevents full activation of their fast-twitch muscle cells (those responsible for sprinting and other “explosive” exercise). It is not known whether the same type of mutation may be present in horses.

Each horse has a unique blend of fast-twitch (favors sprinting) and slow-twitch (favors distance or endurance) muscle fibers. Bottom line: no matter what type of training is used, a particular horse can run only so fast, with his performance limited by genetics and other factors.