Cardio grades

by Bob Fierro With apologies to Pliny the Elder, who more than two centuries ago penned those words in the headline, and also to Elvis, who expanded their meaning in a modest ballad of the same name in 1962, we are about to examine what has evolved after at least 40 years as a science-based axiom of racing efficiency and success: How much of a factor does the cardio system of a Thoroughbred influence its ability? Let us state up front that the answer to that question may depend on...