What makes a Kentucky Derby champion? Big hearts, immense lungs and powerful legs

LOUISVILLE, Ky. (AP) — On a crisp, clear morning, a chestnut thoroughbred thundered down the dirt strip at Churchill Downs, his exercise rider leaning forward above the saddle. Other horse-and-rider pairs followed.Dr. Will Farmer looked down from a viewing point, admiring the speed and agility of the 1,000-pound animals.The whole world will have the chance to see horses in action here Saturday, when the Kentucky Derby shines a global spotlight on equine a